Post on 27-Mar-2015
Nucleon Decay Searchwith LENA
DOANOW 07Honolulu, Hawaii
M. WurmTechnische Universität
München, Germanymwurm@ph.tum.de
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
LENA OverviewTU MünchenMichael Wurm
various sources emit e,inverse -decay allows
precision measurements
LENA OverviewTU MünchenMichael Wurm
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
LENA OverviewTU MünchenMichael Wurm
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
LENA OverviewTU MünchenMichael Wurm
LENA OverviewTU MünchenMichael Wurm
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 DecayTU MünchenMichael Wurm
_
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 DecayTU MünchenMichael Wurm
PROTON DECAY
EVENT SIGNATURE
Challenge:short decay time of the Kaon (12.8ns)
Kaon decay after 18ns
Kaon decay after 5ns
Proton DecayTU MünchenMichael Wurm
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
Proton DecayTU MünchenMichael Wurm
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
Proton DecayTU MünchenMichael Wurm
Proton DecayTU MünchenMichael Wurm
BACKGROUND SOURCES
HADRON PRODUCTIONPION PRODUCTION
KAON PRODUCTION
Calculated background rate:
0.064 per year
Proton DecayTU MünchenMichael Wurm
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 DecayTU MünchenMichael Wurm
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.
_