Transcript Low Energy Neutrino Astronomy with the Large Liquid

Nucleon Decay Search
with LENA
DOANOW 07
Honolulu, Hawaii
M. Wurm
Technische Universität München, Germany
[email protected]
http://www.e15.physik.tu-muenchen.de/research/lena.html
THE LENA DETECTOR
DETECTOR DIMENSIONS
inner detector
- 50kt of organic liquid scintillator (Ø 26m)
- 13,500 photomultipliers
outer muon veto
- water Čerenkov detector
- 2m of active
shielding
LOCATION
- mine or deep
see plateau
- depth of 4,000 m.w.e.
to reduce m-&cosmogenic background
Michael Wurm
TU München
AN OVERVIEW
proton decay
solar neutrinos
terrestrial neutrinos
atmospheric neutrinos
artificial neutrino sources
supernova neutrinos
diffuse SN neutrino background
PHYSICS GOALS
LENA Overview
LENA OVERVIEW
ALTERNATIVE CONFIGURATIONS
vertical detector
cheaper excavation
avoids bouyant
forces
Michael Wurm
TU München
3 detectors à 25kt
plus storage tank
simpler repair & service
detector permanently online
LENA Overview
LENA OVERVIEW
ANTINEUTRINO SPECTROSCOPY
__
various sources emit ne,
inverse b-decay allows
precision
measurements:
_
ne + p → n + e+
Petcov,Schwetz
hep-ph/0607155
_
reactor ne
50-25,000 ev. per year,
precision measurement
of q12~1%, Dm12~10%
Hochmuth et al.
Astrop.Phys 27, 21
hep-ph/0509136
_
terrestial ne
~1,000 events
per year
Michael Wurm
interaction of solar ne’s
spin with magnetic fields
_
can flip them to ne
5,000 7Be ne per day
Supernova @10kpc:
_
~9,000 ne events
matter effects in SN
envelope and earth
diffuse SN neutrinos
_
~10 ne per year, test of
SNR & SN models
TU München
Wurm et al.
PRD 75 023007
astro-ph/0701305
LENA Overview
LAGUNA
Large Apparatus for Grand Unification
and Neutrino Astrophysics
coordinated R+D design study
in European collaboration,
on-going application for EU funding
LENA
Liquid-Scintillator Detector
13,500 PMs for 50 kt of target
water Čerenkov muon veto
MEMPHYS GLACIER
Water Čerenkov Detector
500 kt target in 3 shafts,
3x 81,000 PMs
Michael Wurm
Liquid-Argon Detector
100 kt target, 20m drift length, LEM-foil readout
28,000 PMs for Čerenkov- and scintillation light
TU München
LENA Overview
LAGUNA
DETECTOR LOCATIONS
COLLABORATING INSTITUTES
APC, Paris, France
CEA, Saclay, France
CPPM, IN2P3-CBRS, Marseille, France
CUPP, Pyhäsalmi, Finland
ETHZ, Zürich, Switzerland
Institute for Nuclear Research, Moscow, Russia
IPNO, Orsay, France
LAL, IN2P3-CNRS, Orsay, France
LPNHE, IN2P3-CNRS, Paris, France
MPI-K Heidelberg, Germany
Max Planck für Physik, München, Germany
Technische Universität München, Germany
Universidad de Granada, Spain
Universität Hamburg, Germany
University of Bern, Switzerland
University of Helsinki, Finland
University of Jyväskylä, Finland
University of Oulu, Finland
University of Padova, Italy
University of Silesia, Katowice, Poland
University of Sheffield, UK
Michael Wurm
TU München
LENA Overview
PROTON DECAY
THE PARTICLE ZOO
POINTLIKE PARTICLES
COMPOSITE PARTICLES
Quarks
up
down
strange
charm
bottom
top
Q
+2/3
-1/3
-1/3
+2/3
-1/3
+2/3
m
1.5-3 MeV
3-7 MeV
95 MeV
1.25 GeV
4.5 GeV
174 GeV
Leptons
electron
muon
tauon
neutrinos (e,m,t)
Q
-1
-1
-1
0
m
511 keV
106 MeV
1777 MeV
< 2 eV
Michael Wurm
Hadrons (qqq) Q
m
proton – uud
neutron – udd
L0 – uds
…
+1
0
0
938 MeV
940 MeV
1.12 GeV
Q
+1
0
+1
m
140 MeV
135 MeV
494 MeV
_
Mesons
_ (qq)
p+ – ud_ _
p0 – uu/dd
_
+
K – us
…
Q – electric charge (in units of e)
m – mass (c=1)
TU München
Proton Decay
PROTON DECAY
THEORETICAL PREDICTIONS
Physics beyond the Standard Model usually require the proton to decay …
GUT SU(5)
dominant decay mode:
p → p0 + e+
predicted proton lifetime: t ~ 1031 yrs
current best limit:
t ≥ 5.4  1033 yrs
e+
P
p0
P
K+
Supersymmetry (SUSY)
_
dominant decay mode:
p→
+n
predicted proton lifetime: t ≤ 1035 yrs
current best limit:
t ≥ 2.3  1033 yrs
K+
_
n
Supergravity (SUGRA)
dominant decay modes:
Michael Wurm
p+
_
+ n_
p→
p → K+ + n
(65.7%)
(33.5%)
TU München
Proton Decay
PROTON DECAY
_
104 p→K+n events were simulated
in LENA using the GEANT4 toolkit,
implementing detector physics …
SIMULATION IN GEANT4
by Teresa Marrodán Undagoitia,
PRD 72 (2005) 075014
SCINTILLATOR MODEL
light yield
excitation decay times
absorption length
scattering length
quenching (Birks‘ formula)
110pe/MeV
3.4ns, 17ns
12m
60m
PHOTOMULTIPLIERS
coverage
quantum efficiency
time jitter
Michael Wurm
30%
17%
~1ns
TU München
Proton Decay
PROTON DECAY
SCINTILLATOR TESTS
SOLVENT
feasible candidates
- purified PXE
- 20/80 mixture of PXE/Dodecane
- LAB
fluorescence time
all provide attenuation length of >10m @430nm
but light yield, scattering length and number
of free protons are also important parameters
attenuation length
scattering length
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?
Michael Wurm
TU München
light yield
Proton Decay
PROTON DECAY
EVENT SIGNATURE
leaves the detector
unnoticed …
_
n
_
nm
2nd signal
Michael Wurm
P
K+
1st signal
Ekin = 105MeV
t = 12.8ns
m+
p0
Ekin = 152MeV
t = 2.2µs
Ekin = 110MeV
t = 84ns
Ekin = 128MeV
t = 26ns
g g
_
+
m n
K+
e+
_
n e nm
TU München
K+
p+
m
Proton Decay
PROTON DECAY
EVENT SIGNATURE
Kaon decay after 18ns
Challenge:
short decay time of
the Kaon (12.8ns)
Kaon decay after 5ns
Michael Wurm
TU München
Proton Decay
BACKGROUND SOURCES
ATMOSPHERIC NEUTRINOS
Kaon decay after 5ns
double stucture hard to see
atmospheric neutrinos
nm flux: 4.8×10-2 MeV-1kt-1yr-1
CC reaction of nm on target nuclei:
nm + AZ → A(Z+1) + m-
fast K+ events are undistinguishable
pulse-shape analysis
cut on signal rise-time
Michael Wurm
TU München
Proton Decay
ATMOSPHERIC NEUTRINOS
RISE-TIME ANALYSIS
... m signal is on average
faster in rise
efficiency of the time cut
eT = 65%
background suppression
B ~ 5×10-5
… Kaon rise-time
spread more widely
Michael Wurm
TU München
Proton Decay
BACKGROUND SOURCES
PION PRODUCTION
HADRON PRODUCTION
Calculated
background rate:
KAON PRODUCTION
Michael Wurm
0.064 per year
TU München
Proton Decay
PROTONS OF 12C
NUCLEAR EFFECTS
energy window:
eE ~ 0.995
BINDING ENERGY
S-state:
P-state:
~ 37 MeV
~ 16 MeV
K+m
FERMI MOTION
momenta
< 250 MeV/c
K+p
shift and broadening of lines
Michael Wurm
TU München
Proton Decay
PROTON DECAY
SENSITIVITY IN LENA
protons in LENA:
detection efficiency:
measuring time:
background rate:
~1.4×1034
0.65
10yrs
0.64
for current limit from SuperK:
t = 2.3×1033yrs  40 events
if no event is seen in 10 yrs:
t > 4×1034yrs (90% C.L.)
Michael Wurm
TU München
Proton Decay
SUMMARY AND OUTLOOK
A 50kt detector like LENA will be a multi-purpose
detector, contributing to the fields of geo- and astrophysics as well as particle physics.
Concerning the search of proton decay, LENA will be _
able to test the SUSY-predicted decay channel pK++n.
Within 10 years of measurement, the current limit could
be improved by more than a factor of 10, resulting in a
new limit of tp > 4×1034 yrs.
Michael Wurm
TU München
Summary&Outlook