dpf 2002 jason detwiler1 kamland. dpf 2002 jason detwiler2 g.a.horton-smith, r.d.mckeown, j.ritter,...
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DPF 2002Jason Detwiler 1
KamLAND
DPF 2002Jason Detwiler 2
G.A.Horton-Smith, R.D.McKeown, J.Ritter, B.Tipton, P.VogelCalifornia Institute of Technology
C.E.Lane, T.MileticDrexel University
Y-F.WangIHEP, Beijing
T.TaniguchiKEK
B.E.Berger, Y-D.Chan, M.P.Decowski, D.A.Dwyer, S.J.Freedman, Y.Fu, B.K.Fujikawa, K.M.Heeger, K.T.Lesko, K-B.Luk,
H.Murayama, D.R.Nygren, C.E.Okada, A.W.Poon, H.M.Steiner, L.A.Winslow LBNL/UC Berkeley
S.Dazeley, S.Hatakeyama, R.C.SvobodaLouisiana State University
J.Detwiler, G.Gratta, N.Tolich, Y.UchidaStanford University
K.Eguchi, S.Enomoto, K.Furuno, Y.Gando, J.Goldman, H.Ikeda, K.Ikeda, K.Inoue, K.Ishihara, T.Iwamoto, T.Kawashima, Y.Kishimoto, M.Koga, Y.Koseki, T.Maeda, T.Mitsui, M.Motoki, K.Nakajima, H.Ogawa, K.Oki, K.Owada, I.Shimizu, J.Shirai, F.Suekane, A.Suzuki,
K.Tada, O.Tajima, K.Tamae, H.WatanabeTohoku University
L.DeBraeckeleer, C.Gould, H.Karwowski, D.Markoff, J.Messimore, K.Nakamura, R.Rohm, W.Tornow, A.YoungTUNL
J.Busenitz, Z.Djurcic, K.McKinny, D-M.Mei, A.Piepke, E.YakushevUniversity of Alabama
P.Gorham, J.Learned, J.Maricic, S.Matsuno, S.PakvasaUniversity of Hawaii
B.D.Dieterle
University of New MexicoM.Batygov, W.Bugg, H.Cohn, Y.Efremenko, Y.Kamyshkov, Y.Nakamura
University of Tennessee
The KamLAND Collaboration
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Introduction to KamLAND
• Kamioka Liquid ScintillatorAntiNeutrino Detector
• KamLAND is a neutrino oscillation experiment that uses a terrestrialsource of neutrinos to investigatethe solar neutrino problem
• KamLAND is a long baselineexperiment to study thedisappearance of electronantineutrinos (
e)
• Liquid Scintillator allows us toprobe lower neutrino energiesthan water Čherenkov detectors
KamLAND reactorexclusion region
(3 years)
Mostly ruled Mostly ruled out by recent out by recent SNO resultsSNO results
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Introduction to KamLAND
KamLAND is part of a traditionof experiments that detect neutrinos
from nuclear power plants
Cross section for
e + p e+ + n
Reactor
e spectrum
Detected E spectrum
(no oscillations)
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KamLAND usesthe entire Japanese
nuclear powerindustry as a
long baseline source
Introduction to KamLAND
KamLAND
80% of flux frombaselines 140 210 km
Kashiwazaki
Takahama
Ohi
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The total electric power produced “as a by-product” of the es is:
•~60 GW or...•~4% of the world’s manmade power or…•~20% of the world’s nuclear power!
A large nuclear submarine parked as close as possible to shore in Toyama bay with reactors at full would produce a 10% excess in KamLAND
Introduction to KamLAND
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Introduction to KamLAND
Neutrino oscillations change both the rate and energy spectrum of
the detected events
Coincidence signal: detect• Prompt: e+ annihilation• Delayed: n capture
180 s capture time
p+e
511keV
511keV 2.2 MeV
d
n
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Introduction to KamLAND
"Dome" Area
Outer DetectorWater Cherenkov
Steel Deck
Steel Sphere
Tyvek light baffles
OD PMT's
Nylon Balloon
• 1 kton liquid scintillator80% paraffin oil20% pseudocumene1.5 g/L PPO
• Paraffin outside thenylon balloon
• radon barrier
• 1879 PMT's1325 17" fast544 20" efficient34% coverage
• 225 Veto PMT'sWater Čherenkov
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KamLAND Construction
Steel Sphere ConstructedSeptember October 1999
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KamLAND Construction
PMT InstallationSummer 2000
Completed September 28
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KamLAND Construction
Balloon Installed and TestedJanuary March 2001
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KamLAND Construction
Oil and Scintillator FillingSpring Summer 2001
Completed September 24
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KamLAND Construction
Infrastructure CompletedJanuary, 2002
Cabling
Front End ElectronicsCalibration Deck and Glovebox
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KamLAND Data
KamLAND Data Collection Started January 22, 2002
Muons:all tubes hit
Singles threshold:200 PMT's hit
Coincidence, prescale,"history" threshold:
120 PMT's hit
Calibrationtriggers
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KamLAND Data
MACRO MACRO ElectronicsElectronics
TriggerTrigger LBL ElectronicsLBL Electronics
Trigger Command
Trigger Command
NSum
DAQDAQ
PMTsPMTs
ESum
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KamLAND Data
Samples (~1.5ns)
AD
C c
ount
s (~
120
V)
Blue: raw datared: pedestalgreen: pedestal subtracted
Waveforms are recorded using Analogue Transient Waveform Digitizers (ATWDs), allowing multi p.e. resolution
The ATWDs are self launching
with a threshold ~1/3 p.e. Each PMT is connected to 2
ATWDs, reducing deadtime Each ATWD has 3 gains (20, 4,
0.5), allowing a dynamic range of
~1mV to ~1V
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KamLAND Data
Converting waveforms into time and charge information
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KamLAND Data
Event Display:through going muon
color is pulseheight
all tubes illuminated
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KamLAND Data
Stopped muon
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KamLAND Data
Cerenkov ring from “corner clipper”
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KamLAND Data
Low energy event
color is time
TimePulseheight
(no OD hits)
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KamLAND Data
Converting time and charge information into event position and energy:
This requires calibration of the PMT's:• Timing: done with a blue laser• Gains: single photoelectron gains with LED's
high pulseheight gains with UV laser
The detector response as a wholeis calibrated with radioactive sources
The position is obtained from a vertex fitThe energy response depends on position
65Zn (1.115 MeV )
60Co (2.505 MeV +)(Note: these are old calibration plots, not
valid for current running conditions)
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KamLAND Data
Reconstructed event positionfor different event energies
1/R2 weight, log scale
Most backgrounds peaknear the edge of thescintillator volume
Balloon
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KamLAND Data
Effect of fiducial volume cuts on the energy spectrum40K (1.46 MeV )
208Tl (2.62 MeV )
Neutrons
210Pb,210Bi
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KamLAND Data
Muon related backgroundsBlack: 4.5 m fiducial volume cutGreen: removed by 2 ms muon vetoBlue: expected 11C from spallation:
12C 11C + nRed: E spectrum following muon veto,
11C subtraction
11C(1.0 MeV +)
Neutrons
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KamLAND Data
Background summary:
• Most backgrounds peak near the balloon• radon decay products (208Tl, 210Pb, 210Bi)• 40K
• Neutron rate and level of muon spallationproducts are consistent
• We can also set limits on certain contaminations:238U 10 16 g/g < 6.4 × 10 16 g/g232Th 10 16 g/g < 1.8 × 10 16 g/g 40K 10 18 g/g < 2.3 × 10 16 g/g
• background rates tolerable for reactor experiment
Now we can add event coincidence and look for neutrinos...
40K limit fit
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KamLAND DataNeutrino Candidate
Prompt SignalE = 3.20 MeV
Delayed SignalE = 2.22 MeV
t = 111 sR = 34 cm
(color is time)
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Summary
• KamLAND is making rapid progress
• background levels are acceptable for the reactor experiment,we are working to reduce them to allow lower energy thresholds
• stay tuned for interesting physics results
• Longer term future: KamLAND solar neutrino experiment
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Solar Neutrinos at KamLAND
• Goal: direct detection of7Be solar neutrinos
• Singles measurement:no coincidence signal
• Low backgrounds required!
7Be signal
(KamLAND proposal)
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Solar Neutrinos at KamLAND
• Radiopurity design goals vs. measurements:238U 10 16 g/g < 6.4 × 10 16 g/g232Th 10 16 g/g < 1.8 × 10 16 g/g 40K 10 18 g/g < 2.3 × 10 16 g/g
• Dominant low energy backgrounds are:
• 85Kr• 210Pb, 210Bi (from Rn decays)
• Working on purification andeliminating leaks to removesuch contamination
85Kr coincidencemeasurement
Observed low energyevent spectrum
14C