LENALENA

Low Energy Neutrino Astrophysics

F F.von Feilitzsch, L. Oberauer, W. Potzel

Technische Universität München

LENA Delta

LENALENA

(Low Energy Neutrino Astrophysics)(Low Energy Neutrino Astrophysics)

Idea: A large (~30 kt) liquid scintillator Idea: A large (~30 kt) liquid scintillator underground detectorunderground detector forfor

Galactic supernova Galactic supernova neutrino detectionneutrino detection

Relic supernovae Relic supernovae neutrino detectionneutrino detection

Terrestrial neutrino detection

Search for Proton Decay

Solar Neutrino Spectroscopy

Neutrino properties

P - decay event

Scintillator: PXE , non hazard, flashpoint 145° C, density 0.99, Scintillator: PXE , non hazard, flashpoint 145° C, density 0.99, ultrapure (as proven in Borexino design studies)ultrapure (as proven in Borexino design studies)

Npe ~ 100 / MeV beta

H2O Cerenkov veto

30 KT scintillator

Possible locations for LENA ?Possible locations for LENA ?

Underground mine

~ 1450 m depth, low radioactivity, low reactor background !

Access via trucks

•loading of detector via pipeline

• transport of 30 kt PXE via railway

•no fundamental security problem with PXE !

• no fundamental problem for excavation

• standard technology (PM-encapsulation, electronics etc.)

• LENA is feasible in Pyhäsalmi !LENA is feasible in Pyhäsalmi !

Pylos (Nestor Institute) in Greece, Pylos (Nestor Institute) in Greece,

on the Cern Neutrino beam (off axis) D~1700 kmon the Cern Neutrino beam (off axis) D~1700 km

Neutrino interactions in the scintillator

υ elastic scattering

υ(x) + e υ(x) + e

υ (x) + p υ(x) + p

ν- inverse ß-decay

_

ν(e) + p n + e(+)

υ nuclear excitation

12C

12B12N

17.3 MeV13.4MeV

15.1MeV

1+ 20ms1+ 11ms1+

ec delayed coincidence

υ(e) interaction

υ(x) interaction

Galactic Supernova neutrino detection with Lena

  

protons). off scattering (elastic (6)

electrons) off scattering (elastic (5)

MeV) 15.1 E(Q CC with (4)

MeV) 17.3 (Q (3)

MeV) 13.4(Q (2)

MeV) 1.8 (Q (1)

x

xx

12*12*1212x

1212e

1212

pp

ee

CC

NeC

BeC

nep

x

x

e

e

Electron Antineutrino spectroscopy

Electron spectroscopy ~ 65~ 65

Neutral current interactions; info on all flavours

~ 4000 and ~ 2200~ 4000 and ~ 2200

~7800~7800

~ 480~ 480

Event rates for a SN type IIa in the galactic center (10 kpc)Event rates for a SN type IIa in the galactic center (10 kpc)

Visible proton recoil spectrum in a liquid scintillator

all flavors

and anti-particles

dominate

J. Beacom, astro-ph/0209136

Supernova neutrino luminosity (rough sketch)Supernova neutrino luminosity (rough sketch)

Relative size of the different luminosities is not well known: it depends on uncertainties of the explosion mechanism and the equation of state of hot neutron star matter

T. Janka, MPA

SNN-detection and neutrino oscillations with LENA

Dighe, Keil, Raffelt (2003)

Modulations in the energy spectrum due to matter effects in the Earth

Scintillator

good resolution

Water Cherenkov

Dighe, Keil, Raffelt (2003)

SNN-detection and neutrino oscillations

SNN-detection and neutrino oscillations

Modulations in the energy spectrum due to matter effects in the Earth

Preconditions for observation of those modulations

• SN neutrino spectra e and are different

• distance L in Earth large enough

• very good statistics

• very good energy resolution

LENA and relic Supernovae Neutrinos

• SuperK limit very close to theoretical expectations

• Threshold reduction from ~19 MeV (SuperK) to ~ 9 MeV with LENA __

• Method: delayed coincidence of e p e(+) n

• Low reactor neutrino background !

Information about early star formation period

SRN

No background for LENA !

Reactor SK

Reactor bg LENA !

Atmospheric neutrinos

LENA SNR rate: LENA SNR rate:

~ 6 counts/y~ 6 counts/y

Solar Neutrinos and LENA:Solar Neutrinos and LENA:

Probes for Density Profile Fluctuations !Probes for Density Profile Fluctuations !

7-Be~200 / h LENA

Balantekin, Yuksel

TAUP 2003

hep-ph/0303169

Terrestrische Neutrinos Terrestrische Neutrinos und LENA und LENA

• was ist die Quelle des terrestrischen Wärmeflusses?

• welchen Beitrag liefert die Radioaktivität?

• wieviel U, Th ist im Mantel?

• ist ein gigantischer natürlicher Kernreaktor im Zentrum die Energiequelle des Erdmagnetfelds?

Wärmefluss aus Wärmefluss aus der Erdeder Erde

•Es wird ein kleiner Wärmefluss aus der Erde gemessen.

80 mW / m80 mW / m22

•Integral:

HHEE 4 10 4 1013 13 W = 40 TWW = 40 TW

(Unsicherheit ~20%):•Das entspricht der Leistung von etwa 104 Kernkraftwerken!

• Die Kruste und der oberste Teil des Mantels sind einer direkten geochemischen Analyse zugänglich.

• Die Theorie: U, K und Th sind “lithophil”, sie akkumulieren in der (kontinentalen) Kruste.

• Danach könnte die ~30 km Kruste soviel U, Th wie der ~3000 km dicke Mantel enthalten.

• U, Th im unteren Teil des Mantels wird extrapoliertextrapoliert von Daten aus dem oberen Mantel.

Wo befindet sich U, Wo befindet sich U, Th?Th?

• U In der (kont.) Kruste

Mc(U) (0.2-0.4)1017 kg.

• Noch größere Unsicherheiten für den Mantel:

Mm(U) (0.2-0.8)1017Kg ??

crust

Upper mantle

KAMLAND: ein erster Blick…KAMLAND: ein erster Blick…

•6 Monate Daten ergibt einen Fit für N(Th+U)N(Th+U) für E< 2.6 MeV •N(Th+U) = 9 N(Th+U) = 9 6* 6*

•Die Unsicherheit* ist dominiert durch Fluktuation der Reaktorsignale•Das Ergebnis ist mit jedem geophysikalischen Modell konsistent: Hrad=(0-100 TW).

Proton Decay and LENAProton Decay and LENA

p K p K • This decay mode is favoured in SUSYSUSY theories

• The primary decay particle K is invisible in Water Cherenkov detectors

• It and the K-decay particles are visible in scintillation detectors

• Better energy solution further reduces background

P P KK+ + event event structure:structure: T (K+) = 105 MeV

nsec

KK++ 63.5 %) K63.5 %) K++

T (+) = 152 MeV T (+) = 108 MeV electromagnetic shower

E = 135 MeV

ee++ s) s) MeV)

ee++ s)s)

•3 - fold coincidence !3 - fold coincidence !

•the first 2 events are monoenergetic !the first 2 events are monoenergetic !

•use time- and position correlation !use time- and position correlation !

How good can one separate the How good can one separate the

first two events ?first two events ?

....results of a first Monte-Carlo calculation....results of a first Monte-Carlo calculation

K

time (nsec)

K

P decay into K and

Signal in LENA

Background

Rejection:

• monoenergetic K- and -signal!

• position correlation

• pulse-shape analysis

(after correction on

reconstructed position)

• SuperKamiokandeSuperKamiokande has 170 170 background events in 1489 1489 days (efficiency 33% 33% ))

•In LENALENA, this would scale down to a background of ~ 5 / y~ 5 / y and

after PSD-analysis this could be suppressed in LENALENA to

~ ~ 0.25 / y0.25 / y ! (efficiency ~ ~ 70%70% )

•A 30 kt detector (~ 10103434 protons as target) would have a

sensitivity of a few 10 a few 103434 years years for the K-decayK-decay after ~10 years measuring time

•The minimal SUSYSUSY SU(5) SU(5) model predicts the K-decayK-decay mode to be dominantdominant with a partial lifetime varying from 10102929y to 10y to 1035 35 yy !

actual best limit from SKSK: 6.7 x 1032 y (90% cl)

Conclusions• LENALENA a new observatory

• complemntary to high energy neutrino astrophysics

• fundamental impact on e.g. geophysics, astrophysics, neutrino physics, proton decay

• feasibiluty studies very promising (Pyhäsalmi)Pyhäsalmi)

• costs ca. 100 - 200 M€