Nucleon Decay Search with LENA DOANOW 07 Honolulu, Hawaii M. Wurm Technische Universität München, Germany [email protected]

Nucleon Decay Searchwith LENA

DOANOW 07Honolulu, Hawaii

M. WurmTechnische Universität

München, [email protected]

http://www.e15.physik.tu-muenchen.de/research/

lena.html

30m

100m

DETECTOR DIMENSIONS

inner detector- 50kt of organic liquid scintillator (Ø 26m)- 13,500 photomultipliersouter muon veto- water Čerenkov detector- 2m of active shielding

LOCATION

- mine or deep see plateau- depth of 4,000 m.w.e. to reduce -&cosmogenic background

proton decaysolar neutrinos

terrestrial neutrinosatmospheric neutrinos

artificial neutrino sources supernova neutrinos

diffuse SN neutrino background

PHYSICS GOALS

THE LENA DETECTOR AN OVERVIEW

LENA OverviewTU MünchenMichael Wurm

atte

nuat

ion

leng

th

scattering length

light yield

LENA OVERVIEW

THE SCINTILLATOR SOLVENT

feasible candidates- purified PXE- 20/80 mixture of PXE/Dodecane- LAB all provide attenuation length of >10m @430nm but light yield, scattering length and number of free protons are also important parameters

WAVELENGTH SHIFTERS

- fluorescence times and therefore time resolution currently under investigation- secondary shifter like bisMSB is needed for emission at 430nm- maybe new shifters with large Stoke‘s shift?

fluorescence time


various sources emit e,inverse -decay allows

precision measurements


LENA OVERVIEW

ANTINEUTRINO SPECTROSCOPY _

interaction of solar e’s spin with magnetic fields

can flip them to e

5,000 7Be e per day

_

Supernova @10kpc:~9,000 e events

matter effects in SN envelope and earth

diffuse SN neutrinos~10 e per year, test of

SNR & SN models

_

_terrestial e

~1,000 eventsper year

_

reactor e

50-25,000 ev. per year,precision measurementof 12~1%, m12~10%

_Petcov,Schwetzhep-ph/0607155

Wurm et al.PRD 75 023007astro-ph/0701305

Hochmuth et al.Astrop.Phys 27, 21hep-ph/0509136

_

LENA OVERVIEW ALTERNATIVE CONFIGURATIONS


3 detectors à 25ktplus storage tank

simpler repair & servicedetector permanently online

vertical detectorcheaper excavation

avoids bouyant forces

LAGUNALarge Apparatus for Grand Unification

and Neutrino Astrophysics

30m

100m

MEMPHYSWater Čerenkov Detector

500 kt target in 3 shafts,3x 81,000 PMs

LENALiquid-Scintillator Detector

13,500 PMs for 50 kt of targetwater Čerenkov muon veto

GLACIERLiquid-Argon Detector100 kt target, 20m drift length, LEM-foil readout28,000 PMs for Čerenkov- and scintillation light

coordinated R+D design studyin European collaboration,

on-going application for EU funding



LAGUNA

DETECTOR LOCATIONS COLLABORATING INSTITUTESAPC, Paris, FranceFranceCEA, Saclay, FranceFranceCPPM, IN2P3-CBRS, Marseille, FranceFranceCUPP, Pyhäsalmi, FinlandFinlandETHZ, Zürich, SwitzerlandSwitzerlandInstitute for Nuclear Research, Moscow, RussiaRussiaIPNO, Orsay, FranceFranceLAL, IN2P3-CNRS, Orsay, FranceFranceLPNHE, IN2P3-CNRS, Paris, FranceFranceMPI-K Heidelberg, GermanyGermanyMax Planck für Physik, München, GermanyGermanyTechnische Universität München, GermanyGermanyUniversidad de Granada, Spain SpainUniversität Hamburg, GermanyGermanyUniversity of Bern, SwitzerlandSwitzerlandUniversity of Helsinki, FinlandFinlandUniversity of Jyväskylä, FinlandFinlandUniversity of Oulu, FinlandFinlandUniversity of Padova, ItalyItalyUniversity of Silesia, Katowice, PolandPolandUniversity of Sheffield, UKUK

PROTON DECAY

THEORETICAL PREDICTIONS

GUT SU(5)

dominant decay mode: p → 0 + e+

predicted proton lifetime: ~ 1031 yrscurrent best limit: ≥ 5.4 1033 yrs

KK++PP__

00ee++ PP

Supersymmetry (SUSY)

dominant decay mode: p → K+ + predicted proton lifetime: ≤ 1035 yrscurrent best limit: ≥ 2.3 1033 yrs

_

Supergravity (SUGRA)

dominant decay modes: p → + + (65.7%)p → K+ + (33.5%)

__

Proton DecayTU MünchenMichael Wurm

PROTON DECAY

SIMULATION IN GEANT4104 p→K+ events were simulatedin LENA using the GEANT4 toolkit,implementing detector physics …

SCINTILLATOR MODEL

light yield 110pe/MeVexcitation decay times 3.4ns, 17nsabsorption length 12mscattering length 60mquenching (Birks‘ formula)

PHOTOMULTIPLIERS

coverage 30%quantum efficiency 17%time jitter ~1ns

by Teresa Marrodán Undagoitia,PRD 72 (2005) 075014


_

PROTON DECAY

EVENT SIGNATURE

KK++PP__

leaves the detectorunnoticed …

__

KK++ KK++

63.4

3%

Ekin = 105MeV = 12.8ns21.13%

Ekin = 152MeV = 2.2µs

Ekin = 110MeV = 84ns

Ekin = 128MeV = 26ns

ee++ __

__ee

1st signal

2nd signal


PROTON DECAY

EVENT SIGNATURE

Challenge:short decay time of the Kaon (12.8ns)

Kaon decay after 18ns

Kaon decay after 5ns


BACKGROUND SOURCES

ATMOSPHERIC NEUTRINOSKaon decay after 5nsdouble stucture hard to see

atmospheric neutrinos flux: 4.8×10-2 MeV-1kt-1yr-1

CC reaction of on target nuclei:

+ AZ → A(Z+1) + -

fast K+ events are undistinguishable

pulse-shape analysiscut on signal rise-time


signal is on average faster in rise

efficiency of the time cut T = 65%

background suppression B ~ 5×10-5

… Kaon rise-time spread more widely

ATMOSPHERIC NEUTRINOS

RISE-TIME ANALYSIS



BACKGROUND SOURCES

HADRON PRODUCTIONPION PRODUCTION

KAON PRODUCTION

Calculated background rate:

0.064 per year


PROTONS OF 12C

NUCLEAR EFFECTS

BINDING ENERGY

S-state: ~ 37 MeVP-state: ~ 16 MeV

FERMI MOTION

momenta < 250 MeV/c

shift and broadening of lines

K+

K+

energy window:

E ~ 0.995


PROTON DECAY

SENSITIVITY IN LENA

protons in LENA: ~1.4×1034

detection efficiency: 0.65measuring time: 10yrsbackground rate: 0.64

for current limit from SuperK: = 2.3×1033yrs 40 events

if no event is seen in 10 yrs: > 4×1034yrs (90% C.L.)

Summary&OutlookTU MünchenMichael Wurm

SUMMARY AND OUTLOOK

A 50kt detector like LENA will be a multi-purposedetector, contributing to the fields of geo- and astro-physics as well as particle physics.

Concerning the search of proton decay, LENA will beable to test the SUSY-predicted decay channel pK++.

Within 10 years of measurement, the current limit couldbe improved by more than a factor of 10, resulting in anew limit: p > 4×1034 yrs.

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Documents

Nucleon Decay Search with LENA DOANOW 07 Honolulu, Hawaii M. Wurm Technische Universität München, Germany [email protected]