LENALENA

Low Energy Neutrino Astrophysics

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 for for

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

artificial neutrino sources

P - decay event

Scintillator: PXE , non hazard, flashpoint 145° C, Scintillator: PXE , non hazard, flashpoint 145° C, density 0.99density 0.99, , Light absorption L= 12mLight absorption L= 12m, , ultrapureultrapure (as proven in Borexino design (as proven in Borexino design studies)studies)

Npe ~ 100 / MeV beta

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 security problem with PXE !

• no 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) 1500 kmon the Cern Neutrino beam (off axis) 1500 km

Construction at a convinient site

transportation to phylos in the sea

sinking to apropriate depth

density of whole construction = 1

Galactic Supernova neutrino detection with Lena (ca 14000

events for 30 kt)  

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)

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

Visible proton recoil spectrum in a liquid scintillator

all flavors

and anti-particles

dominate

J. Beacom, astro-ph/0209136

Scintillator

good resolution

Water Cherenkov

Dighe, Keil, Raffelt (2003)

SNNSNN-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

- +

SNR

No background for LENA !

Jap. Reactors in SK

Reactor bg LENA !

Europ. Reactors @800 km

Atmospheric neutrinos

LENA SNR rate: LENA SNR rate:

~ ~ 6 counts/y6 counts/y

Solar Neutrinos and LENA:Solar Neutrinos and LENA:

Probes for Density Profile Fluctuations (p-modes)!Probes for Density Profile Fluctuations (p-modes)!

7-Be~200 / h LENA

Balantekin, Yuksel

TAUP 2003

hep-ph/0303169

terrestrial neutrinos in terrestrial neutrinos in LENALENA

..what is the source of the terretrial what is the source of the terretrial heat flowheat flow?

•What is the contribution from radioactivity?

•How much U, Th is in the mantel?

• is there a TW reactor in the center of the earth?

Where is the U, Th

Heat flow from Heat flow from the earththe earth

•Measured:

80 mW / m80 mW / m22

•Integral:

HHEE 4 4xx101013 13 W = 40 TWW = 40 TW

(uncertainty ~20%):•This corresponds to 104 nuclear power plants!

• The crust and mantel may be analyzed directly.

• Theory: U, K und Th may be“lithophil”, may accumulate in the continental crust.

• ~30 km crust may content as much as 300 km of mantel.

• U, Th in lower part of mantel presently estimated by extrapolation from upper mantel .

Where is U, Th?Where is U, Th?

• U In the (kont.) crust

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

• Still higher uncertaities for mantel:

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

crust

Upper mantle

KAMLAND: a first insight to terrestrial neutrinosKAMLAND: a first insight to terrestrial neutrinos

6 months of data •N(Th+U) = 9 N(Th+U) = 9 6* 6*•@E ν@E νee <2,6 MeV <2,6 MeV

•Uncertainty dominated •by reactors

_

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 :

• mono energetic 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)

LENALENA a new observatory

• complementarely to high energy neutrino astrophysics

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

• feasibility studies very promising (PyhäsalmiPyhäsalmi))

• costs ca. 100 - 200 M€ (30KT)

•make it bigger = longer, several modules

Electron antineutrtino detectionfrom artificial ß-decay sources

Delayed coincidence => background rejection

νe + p => n +e 200μs

n + p => D +2,2 MeV

Remaining dominant background from fast n pulse shape discrimination, Veto by H2O cerencov shield

Self shielding of scitillator

+_

Δ ~ 35% @5 MeV

Burn up of U in PWR (Gösgen)

Example: νe Spectrum as a function of burn up (Gösgen Reaktor)

_

Expected rates in LENA 50 KT

1 c/d @100Km/ 1GW reactor (with oscillations)

Is this enough for identification of Pu production?

Shape of 235U/239Pu 20% diff.

@ E(νe) =5 MeV after full burn up

100 events after 3 months

_

LENA up to 100 KT may be movable Go to the source

(Total density of LENA may be = 1)

Similar to size of oil tanker or submarine

For test of burn up in reactor Low energy threshold very helpful

For background rejection (cosmic rays)at shalow depths puls shape discrimination useful

(Fast neutron background in BOREXINO<< 1 event/a 100T)