Towards neutrino mass determination by electron capture Yuri Novikov PNPI (St.Petersburg) PNPI...

Towards neutrino mass determination by electron capture

Yuri Novikov Yuri Novikov

PNPI (St.PetersburgPNPI (St.Petersburg)) and GSI (Darmstadt)

Symposium in Milos: May 20, 2008

Agenda Ideas

Experimental base

Experimental feasibility

First experimental steps

Problems

NeuMa programme and collaboration

Yu. Novikov, Milos – 20.05.08

History of m measurements

1940 1950 1960 1970 1980 1990 2000 20101

10

100

1000

10000

Year

Lim

it on

m,

eV

from - decay from decay

3 H

35S

3 H3 H

37A

r &

22N

a

3 H

3 H16

3 Ho

193 P

t16

3 Ho

3 H

187 R

e

163 H

o


Do we need to measure the neutrino mass since the

antineutrino mass limit is known?

To confirm the results taken from tritium measurements (with completely different systematic uncertainties).

To check the conservation of CPT:• mν = mνˉ ?

significant difference might be expected because of neutrino mass smallness

·


Yes !

Nuclear processAtomic process

Time rangestart

0 10-18s 10-10s

Z-1N+1

ZN

Electron vacancy

KX

LX

Auger electron

e

Yu. Novikov, Milos – 20.05.08courtesy of J. Khuyagbaatar

General information on the capture energetics

(Z-1,A)g

(Z-1,A)h

(Z,A) + e (Z-1,A)h + E

Q = E + m = Q–i

(Z-1,A)g + Bi

Q–i should be as small as possible

QkeV

The less Qν, the bigger contribution of m

(Z,A)

Q Bi

Q

Z,A

E

EmQi

smaller Ehigher contribution of m

(precision ~1 eV)BBi i – – ееlectron binding energylectron binding energy : :

QQ::1110~

M

M(precision ~1 eV)

mm10 10 eVeV

Yu. Novikov, Milos – 20.05.08Courtesy of S. Eliseev

163Dy

2.0468 M1

1.8418 M2

1.6756 M3

1.3325 M4

1.2949 M5

5-

2

N1-7

163H o

7 -

2

The best candidate for mν-measurement

Qε=

2.4-

2.8

keV

T1/2=4.57 ky


Ultra-precise mass measurements


Principle of Penning Trap Mass Spectrometry

Cyclotron frequency:

Bm

qfc

2

1

B

q/m

B

q/m

• PENNING trap• Strong homogeneous

magnetic field• Weak electric 3D

quadrupole field

z0

r0

ring electrode

end capFrans Michel

PenningHans G.Dehmelt

Typical frequenciesq = e, m = 100 ,B = 6 T

f- ≈ 1 kHzf+ ≈ 1 MHz Yu. Novikov, Milos – 20.05.08

(courtesy of K. Blaum)


High resolution bolometers

Low temperature micro-calorimeters

Operation at low temperatures (T<100mK):

• small heat capacity

• large temperature change

• small thermal noise

Temperature rise upon absorption:

Recovery time:

absorber

x-ray

thermometer

thermal link

thermal bath

Yu. Novikov, Milos – 20.05.08(courtesy of L. Fleischmann)

totC

E

T

MT

T

MM

BMetallic magnetic calorimetersMetallic magnetic calorimeters

Magnetic FieldE

nerg

y

Very simple theory :

Sensor material consists of magnetic moments only 2 level systemsZeeman like energy splitting E = mB 1.5 eV

Energy deposition of 100 keVNumber of flips 1011

Change of magnetic moment

10 B12

BE

m


Advantages of cryogenic micro-calorimeters

Very high energy resolution (σE ≈ 1 eV for Е ≈ 1 keV).

Very small internal background due to small detector dimensions (≈ 100 μ).

Due to long pulse rise (≈ 1 μs), all the atomic (molecular) de-excitations, being shorter than ns, are detected.

Small detector dimensions allow the use of a multi-detector system, which avoids pile-up background.


0 500 1000 1500 2000 2500100

101

102

103

104

Q=2580 eV Q=2300 eV

Sig

na

l /

a.u

.

O1

N2

N1

M2

E / eV

M1

Simulated calorimetric spectrum of 163Ho→163Dy


How can we derive the neutrino mass from electron-capture ?

Total capture probability for allowed transition:

Capture ratios for '2' and '1' atomic levels:

, where Wi = Qε - Bi

(i = 1,2)

η can be determined from – ratio, where

i

iiiii bWqnMMg 221

20

22 })1,1()1,1({4

1

1

2

1

2

1

2

q

q

W

W

)( 22mWq ii

2/1

2ln

T /i

CalorimeterCalorimeterPenning trapPenning trap

Calorimeter + SpectroscopyCalorimeter + Spectroscopy m


Dependence of neutrino mass value on Q and λM2/λM1 for 163Ho-decay

eVm ,

12 /

eVm ,

12 /on dependence mass Neutrino value-on dependence mass Neutrino Q

eVQ,

095.01

2 105.0

1

2 eVQ 2700

eVQ 2600


A. De Rujula and M. Lusignoli

Calorimetric spectrum dS/dEC and "figure of merit"

EQEC

42)0(

2222/1222 h

hCh

hhCC

CBEmEQEQGMdE

dS

hB -is electron binding energy for the hole "h"

2/12222 )0( mBQBQGMS hh

hh

)(163163 EDyHo e

h

CEDy 163


Q

mQ CC dE

mEdSdE

QSmQq

)0,(

)(

1),(

Shapes for “calorimetric” lines of 163Ho→163Dy for Qε=2580 eV

2577,0 2577,5 2578,0 2578,5 2579,0 2579,5 2580,00

2

4

6

8

M1

m=0 eV

Sig

na

l /

a.u

.

E / eV

M1

m=2 eV

M2, Ni, Oi (i=1,2)


0 2 4 6 8 10 12 14 16 18 20 22

-12,0

-11,5

-11,0

-10,5

-10,0

-9,5

-9,0

-8,5

-8,0

-7,5

-7,0

-6,5

m / eV

Lo

g(q

)

Q=2300 eV Q=2580 eV Q=2800 eV

"Figure of merit" q for different Qε and m 163Ho→163Dy


mNeutrino mass, eV

Figure of merit q

Rate / s Expected T, days

2 10-10-10-11 2·105 60-600

10 10-8-10-9

2·105

2·104

2·103

1-106-60

60-600

Data acquisition time T for S=20 events at the edge



Feasibility of the Programme

Most precise mass measurements worldwide:

• performed with Penning traps

• stable nuclides

• closed systems

• detection of the image current

Nuclide Relative uncertainty

Reference

4He 1.6*10-11 R.S. Van Dyck et al., Phys. Rev. Lett. 92 (2004) 220802.

13C2H2 – 14N2

7*10-12 S. Rainville et al., Science 303 (2004) 334.

32S 5.0*10-11 W. Shi et al., Phys. Rev. A 72 (2005) 022510.4He 2.5*10-10 T. Fritioff et al., Eur. Phys. J. D 15 (2001) 141.

Yu. Novikov, Milos – 20.05.08 (courtesy of S. George)

Energy resolution


C

ount

s /

0.24

eV

C

ount

s /

0.12

eV

Energy E [keV] Energy E [eV]


Search for new candidates

BK

BL

BM

BN

(Z,A)

Q b-

(Z -1 ,A)

(Z-1,A)

Qb -

(Z-1,A)

Qb -

(Z-1,A)

Qb -

Qec

(Z+1,A)

Qec

(Z+1,A)

Qec

(Z+1,A)

Qec

(Z+1,A)

Differences in the neutrino massdetermination in β- and EC- processes

m < Qβm < Qec- Bi


Candidates with evaluated Q100 keV

80 100 120 140 160 180 2000

20

40

60

80

100

163 H

o

205 P

b

202 P

b

194 H

g

193 P

t

178 W

157 T

b

150 P

m

136 C

s

123 T

e

Q(

keV

)

A

82B

r

163Dy

2.0468 M1

1.8418 M2

1.6756 M3

1.3325 M4

1.2949 M5

5-

2

N1-7

163H o

7 -

2

Qε=

2.6

keV

T1/2=4.57 ky

EE≈≈0.55 keV0.55 keV

Qε=

(69±

14)

keV

T1/2=444 y

EE=(-12±14) keV=(-12±14) keV

194Hg0+

194Au

80.725 K

1-

Qε=

(50±

15)

keV

T1/2=50 ky

EE≈≈(-35±15) keV(-35±15) keV

202Pb0+

202Tl

15.35 L1

2-

Electron capture

Qε (keV) Method Group

194Hg→194Au ≈35 from T1/2 ISOLDE (1981)

30±40 Schottky ESR-GSI (2005)

69±14 Evaluationwith measured

194Hg at ISOLTRAP

AME (2003)

202Pb→202Tl 55±20 X-ray spectroscopy Argon (1954)and AME

(2003)

50±15 Evaluation with the revised value for Qε=35±25 keV of

Yale (1971)

AME (2003)


Resonant neutrinoless double-capture

(Z,A)

(Z-1,A)

(Z-2,A)

ГГ

εεεε

QQεεεε

BBii(2)(2)

BBjj(1)(1)


22)2()1(

22

21

2

00

41

)0()0(

ji

eeres

BBQmMc

Candidates for resonant neutrinoless double-capture

εε- transition Qεε (keV) E=Eγ+B1+B2 (keV) Δ=Qεε-E (keV) First prediction

74Se+74Ge 1209.7(6) 1207.14(1)(γ+L1+L2) 2.6±0.6 D. Frekers (2005)

112Sn+112Gd 1919(4) 1925.6(2)(γ+K+K) -6.6±4.0 J. Bernabeu et al., (1983)

152Gd+152Sn 54.6(12) 56.26(K+L1)54.28(L1+K)

-1.6±1.2-0.32±1.20

Z. Sujkowski andS. Wycech (2004)

154Er+154Dy 23.7(21) 19.01(L1+L1) 4.7±2.1 “—————”



First steps in implementation

First steps implemented

• FaNtOME – conception for FaNtOME – conception for FaFacility for cility for NNeueuttrino rino OOriented riented MMass ass EExploration, based on 5-Penning trap spectrometer, has been elaborated xploration, based on 5-Penning trap spectrometer, has been elaborated at MPI-K (Heidelberg).at MPI-K (Heidelberg).

• Careful analysis of possible pile-up background for Careful analysis of possible pile-up background for 163163Ho-decay in the Ho-decay in the calorimetric spectrum has been performed.calorimetric spectrum has been performed.

• The background for micro-calorimeter was measured in the keV-region. The background for micro-calorimeter was measured in the keV-region. The result 1 event/100 days, obtained in Genova-Uni, opens very The result 1 event/100 days, obtained in Genova-Uni, opens very promising possibility to implement long-term measurements. promising possibility to implement long-term measurements.

• Experiments to search for new candidates for neutrino mass Experiments to search for new candidates for neutrino mass determination by electron capture are prepared at CERN (ISOLTRAP). determination by electron capture are prepared at CERN (ISOLTRAP). The runs are scheduled for 2008. The runs are scheduled for 2008.


• The investigation of calorimetric spectrum of The investigation of calorimetric spectrum of 163163Ho, implanted in absorber Ho, implanted in absorber by irradiation from ISOLDE mass separator at CERN, was started in by irradiation from ISOLDE mass separator at CERN, was started in Genova.Genova.

Problems, which hopefully can be solved

• Systematic uncertainty in the Penning trap measurementsSystematic uncertainty in the Penning trap measurements

((can be solved by using of 5 Penning trap systemcan be solved by using of 5 Penning trap system))

• Perturbations to spectra and decay rates in the calorimetric absorbers Perturbations to spectra and decay rates in the calorimetric absorbers ( (effect can be measured by using an external sourceeffect can be measured by using an external source))

• Pile-up backgroundPile-up background

((can be measured independentlycan be measured independently))

• Other problems ???????Other problems ???????


We are eager to overcome forthcomingWe are eager to overcome forthcoming

difficulties, meanwhile the neutrino physicsdifficulties, meanwhile the neutrino physics

community should be patient to long-termcommunity should be patient to long-term

efforts and should be keenly aware thatefforts and should be keenly aware that

""Rome was not built in a Rome was not built in a dayday""


ConclusionsConclusions


Absolute neutrino mass measurements by electron capture have two motivations:

• to confirm the existing limit for mass taken from the antineutrino mass measurements (if CPT is conserved),• to check the CPT conservation itself.

To implement this task, a combination of measurements with new generation Penning trap systems and low energy cryogenic micro- calorimeters is proposed.

First steps in the NeuMa project show the feasibility of neutrino mass determination at the level ≤10 eV for electron capture in 163Ho.

We can expect further improvements in the development of ingenious technique, and also in the search for new candidates for precise neutrino mass determination.

The proposed method could also be used to search for neutrinoless resonant double electron capture.

CollaborationCollaboration NeuMaNeuMa

• GSI, GSI, DarmstadtDarmstadt ─ (H.-J. Kluge)

• MPI-K, Heidelberg ─ (K. Blaum)

• University, Genoa ─ (F. Gatti)

• KIP, Uni-Heidelberg ─ (C. Enss)

• PNPI and University, St.Petersburg ─ (Yu. Novikov)

• ISOLDE, CERN ─ (A. Herlert)

• JYFL, Jyväskylä ─ (J. Äystö )• University, Mainz ─ (K. Blaum)

Expected cost of NeuMa program is a few M€


Nuclear Physics

High Energy Physics

AstroPhysics

AtomicPhysics

ParticlePhysics

νFortes Fortuna juvat !!! Fortes Fortuna juvat !!!


Towards neutrino mass determination by electron capture Yuri Novikov PNPI (St.Petersburg) PNPI...

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