n e appearance search
description
Transcript of n e appearance search
May 30, 2001 Yoshihisa OBAYASHI 1
e appearance search
Yoshihisa OBAYASHI(KEK - IPNS)
May 30, 2001 Yoshihisa OBAYASHI 2
Three Active Neutrino & Mass Degeneration Scenario (m2
12<<m213~m2
23)
Present Limit: sin2213>10-1@m2~3x10-3eV2
Obtained by CHOOZ (PALO VERDE) experimentNeutrino Beam is Essentially Pure
(: e~100:0.2@peak)Optimum neutrino energy: below 1GeV
1322
222
2sin5.02sin
)27.1(sin)2(sin)(
e
ee ELmP
to e oscillation search
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Appearance SignalQ.E.e C.C. interaction
No hadronNo recoiled proton ringSingle electron shower
Single Fussy RingCherenkov Angle ~ 42o
E can be reconstructed
ee+- shower
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BG(1): C.C. interactionSharp Ring EdgeCherenkov Angle < 42o
Good PID (atm. study)
Easy to reject
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→2If 2 rings overlap or
A ring is too weak
single ring likeNot Reproduce E
BG(2): N.C. 0 production
→
2 showers
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e selectionSK Atm official selection (single-ring e-like):
Fully Contained (No Anti-counter Activity)Only one ring is reconstructedPID likelihood is e-like (Showering)Evis > 100MeVNo Muon Decay Electron
C.C. N.C. Beam e Osc’d e
Generated 10713.6 4080.3 292.1 301.6
1ring e-like 14.3 247.1 68.4 203.7
red. eff. 0.1% 6.1% 23.4% 67.5%
m2=3x10-3eV2,
sin22e=0.05
We need to reject more!
Number of events for JHF(0.77MW) 5yr exposure to Super-Kamiokande(22.5kt)
May 30, 2001 Yoshihisa OBAYASHI 7
Tight e/0 separationShower direction w.r.t. beam
cose: from 0 tend to have a forward peakForce to find 2nd ring and…
E(2)/E(1+2): Large for BGLikelihood diff. between 1-ring and 2-ringsInvariant mass: Small for e
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Expected Backgrounds & Signal
C.C. N.C. Beam e Osc’d e
Generated 10713.6 4080.3 292.1 301.6
1ring e-like 14.3 247.1 68.4 203.7
red. eff. 0.1% 6.1% 23.4% 67.5%
e/0 sep. 3.5 23.0 21.9 152.2
red.eff. 0.03% 0.6% 7.5% 50.4%
.4<E<1.2 1.8 9.3 11.1 123.2
red.eff. 0.02% 0.2% 3.8% 40.8%
m2=3x10-3eV2,
sin22e=0.05
Number of events for JHF(0.77MW) 5yr exposure to Super-Kamiokande(22.5kt)
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Expected Signal & BG distributionReconstruct E as Quasi-Elastic interactionApply Energy Cut
0.4GeV< E <1.2GeV (OAB2o)
OAB2o 5year
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Sensitivity for Mixing Anglesi
n2 2
e sen
sitiv
ity
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Sensitivities Sensitive down to sin22e~3x10-3
@m2=3x10-
3eV2
By tuning E, sensitive down to sin22e~5x10-3 in all allowed m2
atm
sin2213~1x10-2 @90% C.L.
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Comparison to Other ProjectsMINOS:
High ECC→ →e may be a serious BG
OPERA(,ICARUS)Tuned to find appearanceMore high ESmall Far Detector
JHF neutrino has highest sensitivity in e appearance search
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Summary ~1 GeV neutrino beam + SK(Water Cherenkov) is a good solution to search:
0.01 < sin2213 < 0.1 @ m2atm.
Expected sensitivity: sin2213~ 0.01 @ 90%C.L.
e appearance sensitivity of JHFnu+SK is higher than MINOS, OPERA.