Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev....

28
Searching for Double Beta Searching for Double Beta Decay with GERDA Decay with GERDA Sabine Hemmer for the GERDA collaboration Università di Padova, INFN Padova Les Rencontres de Physique de la Vallée d'Aoste Les Rencontres de Physique de la Vallée d'Aoste La Thuile, 26 February – 3 March, 2012 La Thuile, 26 February – 3 March, 2012

Transcript of Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev....

Page 1: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Searching for Double Beta Searching for Double Beta Decay with GERDADecay with GERDA

Sabine Hemmer for the GERDA collaboration

Universitagrave di Padova INFN Padova

Les Rencontres de Physique de la Valleacutee dAosteLes Rencontres de Physique de la Valleacutee dAosteLa Thuile 26 February ndash 3 March 2012La Thuile 26 February ndash 3 March 2012

Outline

Sabine Hemmer 27 February 2012 1

Neutrinoless double beta decay (0νββ)

The GERDA experiment

First data

Phase II preparations

Why do we search for 0νββ

Sabine Hemmer 27 February 2012 2

Unveil the nature of neutrinos

If 0νββ observed Neutrino is a Majorana particle (ν=ν) Lepton number violation ΔL=2 Sheds light on absolute neutrino mass scale Sheds light on neutrino mass hierarchy

Majoranaν=ν

Diracνneν

or

2νββ and 0νββ

Sabine Hemmer 3

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

allowed by SM ΔL=0 observed in many isotopes T

12~1019-1021y

Forbidden process in SM needs Majorana neutrino

ΔL=2 (T

12)-1 = G0ν (Q

ββZ)middot |M0ν|2 middot ltm

ββgt2

G0ν (Qββ

Z) Phase space (~Qββ

5)

|M0ν|2 nuclear matrix elementltm

ββgt2=|sum

iU

ei2m

i|2

27 February 2012

Experimental signature

76Ge

Peak at Qββ

2νββ and 0νββ

Sabine Hemmer 427 February 2012

2νββ0νββ

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

Searching in 76Ge

Advantages of Germanium

High ε Source = Detector Small instrinsic b High purity Ge Excellent ΔE FWHM ~ (01-02) Well-established technology

Disadvantages of Germanium

High external b Qββ

=2039keV

Small a of 76Ge 78 rarrEnrichment needed

Limited sources of crystal amp detector manufacturers

Sabine Hemmer 527 February 2012

Ssimϵsdotasdotradic MsdottbΔE

S sensitivityε efficiencya abundance of 2νββ isotopeM detector mass

t measured timeb background indexΔE detector resolution

Germanium detector

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 2: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Outline

Sabine Hemmer 27 February 2012 1

Neutrinoless double beta decay (0νββ)

The GERDA experiment

First data

Phase II preparations

Why do we search for 0νββ

Sabine Hemmer 27 February 2012 2

Unveil the nature of neutrinos

If 0νββ observed Neutrino is a Majorana particle (ν=ν) Lepton number violation ΔL=2 Sheds light on absolute neutrino mass scale Sheds light on neutrino mass hierarchy

Majoranaν=ν

Diracνneν

or

2νββ and 0νββ

Sabine Hemmer 3

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

allowed by SM ΔL=0 observed in many isotopes T

12~1019-1021y

Forbidden process in SM needs Majorana neutrino

ΔL=2 (T

12)-1 = G0ν (Q

ββZ)middot |M0ν|2 middot ltm

ββgt2

G0ν (Qββ

Z) Phase space (~Qββ

5)

|M0ν|2 nuclear matrix elementltm

ββgt2=|sum

iU

ei2m

i|2

27 February 2012

Experimental signature

76Ge

Peak at Qββ

2νββ and 0νββ

Sabine Hemmer 427 February 2012

2νββ0νββ

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

Searching in 76Ge

Advantages of Germanium

High ε Source = Detector Small instrinsic b High purity Ge Excellent ΔE FWHM ~ (01-02) Well-established technology

Disadvantages of Germanium

High external b Qββ

=2039keV

Small a of 76Ge 78 rarrEnrichment needed

Limited sources of crystal amp detector manufacturers

Sabine Hemmer 527 February 2012

Ssimϵsdotasdotradic MsdottbΔE

S sensitivityε efficiencya abundance of 2νββ isotopeM detector mass

t measured timeb background indexΔE detector resolution

Germanium detector

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 3: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Why do we search for 0νββ

Sabine Hemmer 27 February 2012 2

Unveil the nature of neutrinos

If 0νββ observed Neutrino is a Majorana particle (ν=ν) Lepton number violation ΔL=2 Sheds light on absolute neutrino mass scale Sheds light on neutrino mass hierarchy

Majoranaν=ν

Diracνneν

or

2νββ and 0νββ

Sabine Hemmer 3

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

allowed by SM ΔL=0 observed in many isotopes T

12~1019-1021y

Forbidden process in SM needs Majorana neutrino

ΔL=2 (T

12)-1 = G0ν (Q

ββZ)middot |M0ν|2 middot ltm

ββgt2

G0ν (Qββ

Z) Phase space (~Qββ

5)

|M0ν|2 nuclear matrix elementltm

ββgt2=|sum

iU

ei2m

i|2

27 February 2012

Experimental signature

76Ge

Peak at Qββ

2νββ and 0νββ

Sabine Hemmer 427 February 2012

2νββ0νββ

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

Searching in 76Ge

Advantages of Germanium

High ε Source = Detector Small instrinsic b High purity Ge Excellent ΔE FWHM ~ (01-02) Well-established technology

Disadvantages of Germanium

High external b Qββ

=2039keV

Small a of 76Ge 78 rarrEnrichment needed

Limited sources of crystal amp detector manufacturers

Sabine Hemmer 527 February 2012

Ssimϵsdotasdotradic MsdottbΔE

S sensitivityε efficiencya abundance of 2νββ isotopeM detector mass

t measured timeb background indexΔE detector resolution

Germanium detector

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 4: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

2νββ and 0νββ

Sabine Hemmer 3

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

allowed by SM ΔL=0 observed in many isotopes T

12~1019-1021y

Forbidden process in SM needs Majorana neutrino

ΔL=2 (T

12)-1 = G0ν (Q

ββZ)middot |M0ν|2 middot ltm

ββgt2

G0ν (Qββ

Z) Phase space (~Qββ

5)

|M0ν|2 nuclear matrix elementltm

ββgt2=|sum

iU

ei2m

i|2

27 February 2012

Experimental signature

76Ge

Peak at Qββ

2νββ and 0νββ

Sabine Hemmer 427 February 2012

2νββ0νββ

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

Searching in 76Ge

Advantages of Germanium

High ε Source = Detector Small instrinsic b High purity Ge Excellent ΔE FWHM ~ (01-02) Well-established technology

Disadvantages of Germanium

High external b Qββ

=2039keV

Small a of 76Ge 78 rarrEnrichment needed

Limited sources of crystal amp detector manufacturers

Sabine Hemmer 527 February 2012

Ssimϵsdotasdotradic MsdottbΔE

S sensitivityε efficiencya abundance of 2νββ isotopeM detector mass

t measured timeb background indexΔE detector resolution

Germanium detector

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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  • Pagina 27
  • Pagina 28
Page 5: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Experimental signature

76Ge

Peak at Qββ

2νββ and 0νββ

Sabine Hemmer 427 February 2012

2νββ0νββ

n

n p

p

e-

e-

νν2νββ

n

n p

p

e-

e-

ν=ν0νββ

Searching in 76Ge

Advantages of Germanium

High ε Source = Detector Small instrinsic b High purity Ge Excellent ΔE FWHM ~ (01-02) Well-established technology

Disadvantages of Germanium

High external b Qββ

=2039keV

Small a of 76Ge 78 rarrEnrichment needed

Limited sources of crystal amp detector manufacturers

Sabine Hemmer 527 February 2012

Ssimϵsdotasdotradic MsdottbΔE

S sensitivityε efficiencya abundance of 2νββ isotopeM detector mass

t measured timeb background indexΔE detector resolution

Germanium detector

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 6: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Searching in 76Ge

Advantages of Germanium

High ε Source = Detector Small instrinsic b High purity Ge Excellent ΔE FWHM ~ (01-02) Well-established technology

Disadvantages of Germanium

High external b Qββ

=2039keV

Small a of 76Ge 78 rarrEnrichment needed

Limited sources of crystal amp detector manufacturers

Sabine Hemmer 527 February 2012

Ssimϵsdotasdotradic MsdottbΔE

S sensitivityε efficiencya abundance of 2νββ isotopeM detector mass

t measured timeb background indexΔE detector resolution

Germanium detector

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 7: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Previous 76Ge experiments

[1] Eur Phys J A12 147-154 (2001)[2] Phys Rev D 65 092007 (2002)

Claim of signal from parts of HdMT

12 (76Ge) = (069 ndash 418)middot1025y (3σ) (Phys Lett B 586 198-212 (2004))

Sabine Hemmer 627 February 2012

HdM IGEX

Location LNGSHomestake Baksan

Canfranc

Exposure [kgmiddoty] 711 89

Bg [countskeVmiddotkgmiddoty] 011 017

T12

limit (90 CL) [y] 19middot1025 [1] 16middot1025 [2]

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 8: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

GERDA physics goal

Ph

ys R

ev D

092

003

(200

6)

F F

eru

glio

A S

tru

mia

F V

issa

ni

NP

B 6

59

Phase IPhase II

18kg (HdMIGEX) enriched (~86) + 15kg natural reach background of 10-2 counts(keVmiddotkgmiddoty) Exposure of 15 kgmiddoty rarr check claim ltm

ββgt le (023-039) eV (Phys Rev C 81 (2010) 028502)

add ~20kg new enr detectors reach background of 10-3 counts(keVmiddotkgmiddoty) Exposure of 100kgmiddoty Trarr

12 gt 15middot1026y

ltmββ

gt le (009-015) eV (Phys Rev C 81 (2010) 028502)

Phase I

Phase II

Sabine Hemmer 727 February 2012

Phase I

Phase II

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 9: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Background reduction

3400 mwe

Sabine Hemmer 827 February 2012

GERDA situtated in LNGS underground laboratories suppression of cosmic ray muons by factor 106 by overlaying rock

Graded shielding against ambient radiation Rigorous material selection Avoid exposure above ground for detectors

High-purity LAr (64m3) shield and coolant (Option active veto)

Phase I array

Clean room

Steel cryostat with internal copper shield

Ultrapure water (580m3) n moderator Cherenkov medium for μ veto

Lock

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 10: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Background reduction

ββ

Ge

Multi-site energy deposition inside HP-Ge diode

(Compton scattering)

γγ βCo-60

Point-like (single-site) energy deposition inside one HP-Ge

diode (Range ~ 1mm)

Signal Background

Signal analysis anti-coincidence between detectors pulse shape analysis (PSA)

Sabine Hemmer 927 February 2012

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 11: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Start of Phase I6 November 2011 Start of Phase I

All 8 enrGe + 4 natGe detectors deployed in GERDA(2 enrGe detectors presently not used for analysis)

natGe 197 kgmiddoty (76 kg)

enrGe 380 kgmiddoty (146 kg)

Sabine Hemmer 1027 February 2012

Energy spectrum

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 12: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

(Unexpected) Background from Argon

101 Bqkg T12

=269 y

pure β emitter Q-value=565keV rarr below region of interest

39Ar

Sabine Hemmer 1127 February 2012

42ArGERDA proposal 42ArnatAr lt 3 x 10-21 (Barabash et al 2002)GERDA measurement Count rate at 1525keV ~ 2 times expectation

Field-free configuration

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 13: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Region of Interest

middot

Background rate in ROI (Qββ

plusmn100 keV blinded window excluded) enrGe 0017+0009

-0005 counts(keVmiddotkgmiddoty)

natGe 0049+0015-0013

counts(keVmiddotkgmiddoty) most likely a combination of ThU 42K degraded α cosmogenic isotopes factor ~10 lower than previous experiments (HdM IGEX) no pulse shape analysis applied yet

ROI

blinded

ROI

blinded

Sabine Hemmer 1227 February 2012

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 14: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

2νββ

middot

39Ar 101 Bqkg from WARP [NIM A574 83-88 (2007)]

76Ge T12

(2νββ)=174middot1021y from HdM

[NIM A513 596-621 (2003)]

42K homogeneously distributed decays in LAr (normalized to peak)

40K simulated decays in detector holders (normalized to peak)

Sum of MC contributionsData

Sabine Hemmer 1327 February 2012

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 15: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Phase II detectorscu

rren

t

time [ns]

ββ decay

ACCEPT

γ ray background REJECT

REJECT42K β UTh chain αs

Peculiar pulses

0νββ-like

90 11

γ-bgd

A

A

Sabine Hemmer 1427 February 2012

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 16: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

BEGe production

Sabine Hemmer 1527 February 2012

Crystal pulling at Canberra Oakridge TN USA

BEGe detector diode production Olen BE

BEGe acceptance tests Hades BE

ONGOING ONGOING

ONGOING

First spectra

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

  • Pagina 1
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Page 17: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

RampD liquid argon instrumentation

photons

Liquid argon

Detection of coincident liquid argon scintillation

light to discriminate background

LarGe Low-background test facility at LNGS

Sabine Hemmer 1627 February 2012

Also other designs investigated rarr avoid additional background

Combining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

  • Pagina 1
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Page 18: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Summary

GERDA Phase I started in November 2011 Unexpectedly high contribution from 42Ar decays Background in ROI lower than in previous experiments (~ factor 10)

but slightly higher than design goal 2νββ spectrum well reproduced by MC (taking into account

contributions from 39Ar 42Ar and 40K) Phase II detector production and RampD on LAr scintillation light

readout ongoing

Sabine Hemmer 1727 February 2012

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

  • Pagina 1
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Page 19: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

The GERDA collaboration

Sabine Hemmer 1827 February 2012

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 20: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

BackupHdM claim

Nov 1990 - May 2003 717 kg year Bgd 011 counts (keVkgy) 2875 plusmn 687 events (bgd~60) 42σ evidence for 0νββ

(069 ndash 418)middot1025 y (3 σ) Best fit 119middot1025 y

mββ

= (024-058) eV

best fit 044 eV

Note statistical significance depends on background model

Phys Lett B 586 198-212 (2004)

Comparison IGEX

D Gonzalez et al NPB (Proc Suppl) 87 (2000) 278

Sabine Hemmer B127 February 2012

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 21: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Backup α events

Sabine Hemmer B227 February 2012

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 22: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Backup calibration

Sabine Hemmer B327 February 2012

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 23: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

BackupNeutrino properties

What we know m

22-m

12=Δm

sun2

m2

2-m1

2=Δmatm

2

θ12

=θsun

θ23

=θatm

θ

13

What we do not know Absolute mass scale Mass hierarchy Phases (δ

13 α

21 α

31)

Nature of the neutrino mass (Dirac or Majorana)

Sabine Hemmer B427 February 2012

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 24: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Shockley-Ramo TheoremQ(t)=-qmiddotΦ

w(r(t))

BackupPhase II detectors

Ew(r)=-nablaΦ

Sabine Hemmer B527 February 2012

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 25: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Backup Background reduction

Key issue Low background rate (Phase I 110 HdM)

sensitivitysimϵsdotasdotradic MsdottbΔ E

Possible backgrounds External

γ from Th and U chain neutrons from spallation μ from cosmic rays

Internal cosmogenic 60Co (T

12=53y)

cosmogenic 68Ge (T12

=271d)

Radioactive surface contamination

Sabine Hemmer B627 February 2012

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 26: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

before MS (059 kgy)

after MS (037 kgy)

Backup Play with the electric fieldAdd a mini-shroud (MS)

70 cm

Shroud (already installed to prevent 222Rn concentration)

+ +- -+ +- -

MSV

S-MS=+700V (019 kgy)

VS-MS

=-400V (037 kgy)

Sabine Hemmer B727 February 2012

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 27: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Backup Muon induced events

dataMC

Spectrum of muon-induced events in Germanium (209 kgy during commissioning)

Estimate of muon veto efficiency for events causing a signal in Ge ε = 987Estimate of muon-induced background at Q

ββ B

μ lt 20middot10-4 countskeVmiddotkgmiddoty

middot

Sabine Hemmer B827 February 2012

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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Page 28: Searching for Double Beta Decay with GERDA · [1] Eur. Phys. J. A12, 147-154 (2001) [2] Phys. Rev. D 65, 092007 (2002) Claim of signal from parts of HdM: T 1/2 (76Ge) = (0.69 –

Operation of Phase II proto-type detector in LarGeCombining PSD of BEGe detector and LAr veto Measured suppression factor for a 228Th source at Q

ββ ~ 05middot104

Also successful read out scintillation light with fibers coupled to SiPMs

Sabine Hemmer B927 February 2012

Backup RampD liquid argon instrumentation

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