LENALENALow Energy Neutrino Low Energy Neutrino

AstrophysicsAstrophysics

L. Oberauer, Technische Universität München

www.e15.physik.tu-muenchen.de/research/lena.htlm

LENA Delta

EL SUD Meeting

Garching, April 24th

Scintillator solvent: PXE, or PXE/mineral oil mixtureScintillator solvent: PXE, or PXE/mineral oil mixture

• non hazardous, flashpoint 145° C non hazardous, flashpoint 145° C easy handlingeasy handling

• density up to 0.99density up to 0.99 high self shielding high self shielding

• high light yieldhigh light yield low energy eventslow energy events

• low background level U, Thlow background level U, Th solar solar geo geo , snr , snr

Muon veto

30% coverage up to ~60% (light cones)

LENA

50 kt liquid scintillator detector

100m

30m

• transport transport of PXE via railwayrailway

• loadingloading of detector via direct pipeline pipeline

• no fundamental no fundamental securitysecurity problem problem with PXE with PXE

• no fundamental problem for excavationexcavation

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

LENA at CUPP

Scintillator for LENAScintillator for LENACTF at Gran Sasso (BOREXINO)

Absorption- and Scattering lengths at TU München (M. Wurm – Diploma thesis)

~ 100 pe / MeV for an event at the center

up to ~ 200 pe / MeV with light cones should be possible

Coverage 30%

Physics goals Physics goals

• Baryon number violation (Proton decay)

• Gravitational collapse (SN detection)

• Star formation (diffuse SN background)

• Thermonuclear fusion processes (low E solar neutrinos CNO, pep, 7Be)

• Geophysical models (U, Th –

• Neutrino oscillations (Long baseline –

Supernovae Relic Supernovae Relic ee

3 models (different spectral shapes):

Lawrence Livermore – LL

Keil, Raffelt, Janka – KRJ

Thompson, Burrows, Pinto - TBP

Large systematic uncertainties

UV (blue), H (green) and FIR (red) are impeded by dust extinction

Contribution to the signal as function of z

Ando et al., 2003

SRN Rate (between 9.8 and 30 MeV):

28 – 55 / (10 a)

Background ~ 8 / (10 a)

Spectral shape analysis possible

Redshift z ~ 2

Separation LL vs. TBP possible (90% cl)

Supernovae Relic Supernovae Relic ee

M. Wurm – Diploma thesis

Supernovae Relic Supernovae Relic ee

Threshold at Kamioka ~ 12 MeV (for water Cherenkov detectors)

Redshift z ~ 1

Between 21% and 37% lower rate (compared to Pyhäsalmi)

Best locations: Hawaii, Australia…

Supernova NeutrinosSupernova NeutrinosAssumption: Supernova II with 8 solar masses at 10 kpc distance

e flux and spectrum

e flux and spectrum

Supernova NeutrinosSupernova Neutrinos

Total neutrino flux

Total energy spectrum

Supernova and neutrino properties

„Wiggles“ in the e spectrum observable

• if spectra or fluxes of SN neutrino flavors differ

• if neutrinos pass the Earth before entering LENA

yes no

Smirnov, Dighe, Raffelt...

Solar NeutrinosSolar Neutrinos

• High statistic ( ~ 5.4 x 103 / day ) 7Be + e + e

test of small flux fluctuations in time

• CNO and pep – neutrinos ( ~ 3 x 102 / day )

solar neutrino luminosity

contribution of CNO cycle to solar energy release

• Charged current e (13C,13N) e- reaction ( ~ 103 / year )

spectroscopy of 8B- at energies below 5 MeV

(A. Ianni et al., hep-ph/0506171)

LENA Fiducial Volume for solar : 18 x 103 m3

Test of MSW effectTest of MSW effect

7Be pep CNO

8B 8B via 13C

MSW

effect

Geo NeutrinosGeo Neutrinos

• Detection via inverse beta decay

• measurement of radiogenic contribution to terrestrial heat (~ 40 TW)

• test of the Bulk Silicate Earth model

• test of unorthodox models of Earth‘s core (is there a breeder reactor ?)

LENA @ Pyhäsalmi: ~ 1.5 x 103 events / year

TNU

(1 capture in 1032 protons per year)

Scaling KamLAND result to LENA:

between

3 x 102 and

3 x 103 events / year

Rate of Geo-neutrinos in LENA

G. Fiorentini et al., hep-ph/0401085

Distinction potential between U- and Th-series

Geo-neutrinos and LENAGeo-neutrinos and LENA

Displacement n,e+ for directionality ?

zenith angle distribution in LENA

e.g. 21 TW core model:

Indication (1 ) after a couple of years

K. Hochmuth – Diploma thesis

K

K

Event structure in LENA

Background suppression ~ 5 x10(-5)

Acceptance ~ 65%

T. Marrodan Undagoitia – Diploma thesis

Actual SK limit 2.3 x 1033 y: after 10 years ~ 40 events (< 1 background event) 90%cl limit: 4 x 1034 years

T. Marrodan et al., Phys. Rev. D 72, 075014 (2005)

LENA and long baseline LENA and long baseline accelerator experimentsaccelerator experiments

Search for 13

e.g. at a Betabeam ( appearance experiment)

Separation between muon- and electron like events ?

Two methods under investigation:

• pulse shape discrimination (works fine for HE)

• muon decay (delayed coincidence)

problem: pion production E > 400 MeV and successive decay into muon

Muon

(800 MeV)

Tau = 8 ns

(risetime 15% - 85%)

Electron

(800 MeV)

Tau = 4 ns

Time (ns)

Muon Electron

ConclusionConclusion

LENA: a low energy neutrino LENA: a low energy neutrino observatoryobservatory

Impact on astro- ,particle-, Impact on astro- ,particle-, geophysicsgeophysics

Complementary to Neutrino Complementary to Neutrino TelescopesTelescopes

Feasibility studies very promisingFeasibility studies very promising