apr. 4, 2001 @ kek jhf-sk neutrino workshop 1 e appearance search yoshihisa obayashi (kek - ipns)
TRANSCRIPT
Apr. 4, 2001 @ KEK
JHF-SK neutrino workshop
1
e appearance search
Yoshihisa OBAYASHI
(KEK - IPNS)
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 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) experiment
Neutrino Beam is Essentially Pure (: e~100:0.2@peak)
e appearance search = small 13 search
232
1322
22
232
132
sin2sin2sin
)27.1
(sinsin2sin)(
e
e E
LmP
to e oscillation search
~0.5 from SK Atm.
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 3
Appearance Signal
e C.C. interaction
Single Fussy Ring
Cherenkov Angle ~ 42o
e
e+- shower
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 4
BG(1): C.C. interactionSharp Ring Edge
Cherenkov Angle < 42o
easy to reject
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 5
→2: 2 Shower Rings 2 rings overlap
A ring is too weak
Not Reproduce E
BG(2): N.C. 0 production
→
2 showers
Single Ring
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 6
0 productionSudden raise from E~500MeV
(w
/0 )
/(t
otal
)
E(GeV)
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 7
e selectionSK Atm official selection (single-ring e-like):
Fully Contained (No Anti-counter Activity)
Only one ring is reconstructed
PID likelihood is e-like (Showering)
No Muon Decay Electron
Evis > 100MeVOAB 2o 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
Too Much!
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 8
Tight e/0 separation0 BG tend to have a forward peak
cose: Large for BG
2nd ring for the signal is fakeE(2)/E(1+2): Large for BG
Likelihood diff. between 1-ring and 2-rings
Invariant mass
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 9
e/0 separation efficiency
OAB 2o 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%
m2=3x10-3eV2,
sin22e=0.05
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 10
0 contaminationBlack: Single-ring e-like ~2%
Green: Standard 0 rejection ~0.2%
Red: More tight 0 rejection ~0.1%
E(GeV)
Eff.
Iden
tifie
d as
e
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 11
BG(3): C.C. +N e could be a source of BG
Energy threshold > 3 GeV
Negligibly small
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 12
Expected Signal & BG distributionReconstruct E as Quasi-Elastic interaction
Apply Energy Cut0.4GeV< E <1.2GeV (OAB2o)
OAB2o 5year
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 13
Sensitivity for Mixing Anglesi
n22
e s
en
sitiv
ity
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 14
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
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 15
Sensitivities (2)
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 16
Comparison to Other ProjectsMINOS:
Too high ECC→→e may be a serious BG
OPERA(,ICARUS)Target physics is different ( app.)
Much more high ESmall Far Detector
Apr. 4, 2001 JHF-SK neutrino workshop @ KEK 17
Summary ~1 GeV neutrino beam + SK(Water Cherenkov) seems to be a best solution to search:
0.01 < sin2213 < 0.1 @ m2atm.
Expected sensitivity:
sin2213~ 0.01 @ 90%C.L.
JHFnu-SK has much higher sensitivity for e appearance search than MINOS and OPERA.