スーパーカミオカンデにおける高エネルギーニュートリノ研究名古屋大学太陽地球環境研究所
伊藤好孝
2005年12月25日基研理論懇シンポ「高エネルギー天体物理学の最前線」

Menu• upgoing µ at Super-Kamiokande• upgoing showering µ• DC point source search– ν from point source– ν from dark matter annihilation• Time correlated search– ν from GRBs, SGRs
– ν from SGR1806-20 burst at Dec27,2005• OD-tagged upgoing VHE µ• (Relic super nova ν)42 mSuper-Kamiokande detector

39.3 m 50kt water Cherenkov
 1000m underground ID viewd by 11176 PMT
 2m thick OD for veto
 Fiducial mass 22.5kt
 Eth~5 MeV (~7MeV for SKII)’96~’01 SK-I
’02~’05 SK-II(w/ half PMTs)’06~SK-III(restore full PMTs)

タンク内の様子

1012

ppSolar νe

cm-2 sec-1 MeV-1

108

SN ν @G.C.

B8reactor νe1041

Atmospheric νµ

10-4
10-8

Neutrinoflux
at Earth
as BG

10-12
10-16
10-20

SK10-2

1102

104

Eν
ν(GeV)

SKでのνサンプルの種別
νUpgoing µFC

νStopping µPCµµ8.2/day

Through going µµ

0.3day0.6/day

1.1dayννEnergy spectrum of ν for each event category
1000
FC ν µFC ν e
PC ν µ7505009.9x10-5 BGν/secup-stop µup-thru µ250

太陽ν太陽νサンプル
7-20MeV

0 −2−1101011010E ν (GeV)

2103104105

10-38 cm2 / nucleon

ν – N cross section

Eν (GeV)σtot = ~ 10-38 cm2 × Eν /(GeV)
1 ν (@1GeV)
1×10-38 cm2 6×1032 N 3.15×107 s
190 int.
=×××cm2s
nucleonktonyearkt yr

ν-lepton 角度：～ ~30度（@GeV)）Easy event rate estimation at SK
FC.PC :Up µ :σ∝Eν V=constσ∝Eν V∝EνNSK∝EνNSK∝Eν2• 1 TeV ν produces up-going through µ at SK• Assuming Eµ ~1TeV, Rµ~1000m
Effective area S=1200m2
1000m

Effective target volume
S x Rµx ρrock ∼ 3x1012gµν• NSK= 10−35 (cm2)×10−7 (ν/cm2/s) ×1036 (proton)~10-6 events/s

Muon Energy loss as a function of Energy
Non-Showering muon Showering Muon
EiLEf

dE/dX = (Ei - Ef)/LDistribution
asymmetricfor each muonenergies(Groom et al 03)
Reasonably good agreement of Monte-Carlo with PDG
Aim of this analysis is only to separate a given muon intoshowering/non-showering普通のµ、radiative µEvent Display of upward showering muon

Corrected Charge Distribution Comparison of ionizing vs showering muon
Muon Energy = 20 GeV

Muon Energy = 10 TeV

dE/dX = 2.16 MeV/cm

dE/dX = 8.5 MeV/cm

Both simulated muons have same entry point and direction

Parent Eν for Up-showering µ

68% ν to thru-µ res.
•1.25o (showering, this fig)
•1.0o (non-showering)Zenith-angle distribution of showering
muons

Showering muons relatively insenstive to oscillation==> For this dataset chi-square for null -oscillation should bevery good fit

Showering Muon Oscillation
Results
Best-fit (physical region) :2 = 4.68 / 7 dof for (m2, sin22) = (0.0104 eV2, 0.9)
Best-fit (null oscillation) :2 = 6.51/9 dof

Zenith angle comparison
at best fit point
Null oscillation
normalized by livetime

Astrophysical high-energy ν searchin SK up-going µ sample
The data presented here “SK-I” (pre-implosion) dataset (full ID PMTs)
1680 live-days ( April 1996 ~ July 2001)
1892 thru-µ(total 2359 up-µ)467 stop-µ（309 of the thru-µ : high-energy showering sort）
 “SK-II” (post-implosion) data set (Half ID PMTs)
for Dec27,2005 SGR1806-20 burst event

Below 54deg
declination

4deg× 4deg bin

Poisson probability
sky mapfor SK-I upµ direction

Fitted slope
1.06+-0.04(χ2/dof=0.89)

Sky location of up-showering µ# of events in 3deg cone

All up-through-µ

No excessup-showering µ

Upµ upper limit on DC flux from point sources
Sourceν

BG

Acceptancex106cm2

90% c.l. limitµ x10-14cm-2s-1Cyg X-16

2.54

3.731

1.486

Cyg X-332.40

3.083

1.049

Her X-1

22.53

3.718

0.680

Sco X-1

32.95

6.533

0.465

Vela X-1

83.69

8.040

0.798

Crab N.

1

2.57

4.776

0.420

3C273

52.70

5.814

0.795

Per A

2

2.49

3.010

0.842

Vir A

42.76

5.329

0.712

Coma cl.

4

2.67

4.358

0.881

Gal. C.

1

3.51

7.144

0.269

Upµ upper limit on DC flux from point sources(cnt’d)
SourceνBG

Acceptancex106cm2

90% c.l. limitµ x10-14cm-2s-1Geminga

32.90

5.034

0.607

Mrk 42122.623.414

0.734

Mrk 501

32.33

3.233

1.008

1ES1426

12.33

2.830

0.713

SGR 1900+1422.51

5.483

0.461

SGR 0526-66

65.17

12.0700.341

1E 1048-5937

55.98

11.9200.273

SGR 1806-20

2

2.84

6.734

0.365

GX339-4

44.39

9.194

0.345

SMC X-1

54.90

12.2030.293

Upµ from Sun,Earth and G.C.
Phys Rev D70:083523,2004

Signal of WIMP annihilation χ χ  ?+ν ν
Spin dep.
Sun104-106 m2  1kg Ge
Spin indep. Sun,Earth 10-500 m2  50gm hydrogen
M.Kamionkowski Phys.Rev.Lett.74 5174(1995)

Constraint on WIMP parameters

SK-I Time correlation serach for GRBν
Astrophys.J.578:317-324,2002• Time correlation with GRBs taken from BATSE catalog• event rate in +-10sec, +-100sec, +-1000sec, 1hour window• No significant excess

Fluence upper limit “Green function”

Fluence limit Ffor given spectrum λ(Eν)

#of LE/HE eventsin +-100s window of GRB

Direcitonal correlation of LE/HE in +-100sec window

GRBν fluence upper limit
cm-2cm-2106
HE106Up µ104
102104

1102

10-2
10-4

110-61Eν(GeV)

102

1Eν(GeV) 10

3Upper limit for E-2 type spectrum (90% CL)< 3.83 ×10-2 cm-2 (2GeV -100TeV)

Soft Gamma-ray Repeater (SGR)[Thompson and Duncan, MNRAS, 1995]• Known as a X-ray burst source (repeating)• Caused by large flare of magnetic filed of neutron star
• Possible source of proton acceleration– p + p or p +γ  N+X+ π+-, π  µν

Time-correlated SGR ν search in SK-I up-µ
• 4 active SGRs during SK-I
data taking• 74 ±one day, 5o windows
around SGR bursts during SK-I
data contained 1 up-µ
• Atmospheric ν background is0.013 events/window; expect
0.96 events total• Signal consistent withbackground, no evidence for a
SGR related ν signal“ “ show
4 bursts of SGR1900+14(26May1998, 21:30:29UT~
27May1998, 04:22:01)

2004年１２月27日２１時30分26秒（UT)

Intense emission
In the first 200ms

SGR1806-20 burst
DEC.2004

SGR1806-20 direction at Kamiokacosθz= -0.020

Just below horizon

SGR1806-20バースト時のニュートリノ事象
BurstFCPCUpµSolarSGR1806-20バースト前後１０日間のニュートリノ事象頻度FCPCUpµDec (deg)Upµdirection
inRA,DEC(in+10days)
90
Events in +7~ +8 days
show by red0-900SGR
180.6h-20 deg

RA (hour)241. Up-µ fluence limit• F = N90 / ( S ε )– N90 = 2.3 (90%Cl limit for 0 upµ w/ no BG)– S = 1200m2 (effective area @cosθz=-0.02)– ε = 80% ( efficiency for µ source from cosθz=-0.02 )Here µ comes from SGR direction
and cos θz cut makes inefficiency for µ due to angular resolution
Upm MC tells ε=80% for µ from cosθ z=-0.02.

F < 2.4 x 10-7 µ cm-2 (90%C.L.)
at the burst period
This is just an experimental observableν/cm2Combined ν fluence limit green function
for Dec27,05 busrt of SGR1806-20
10

νe fluence limit (90 %CL) all combined

11108105102

all combinedνµ combined
νe combined-11010-210-1

110102310Eν (GeV)

Upper limit for E-2 type spectrum (90% CL)
E2Φν < 8 ×101 cm-2 s-1 GeV (@1GeV -100TeV)

SK-I up µ time and directional correlation search• 1 doublet foundTwo up-µ’sseparated by 2.7 deg
and arrived within 19min.
(RA,DEC)=(7.4h,16.3o)
Chance coincidence = 2×10-5/ doublet
 5% chance for all doublets

Very High Energy upgoing µ tagged by OD• VHE µ bremsstrahlung events w/ > 1.75×106pe
have been rejected from up µ sample ( Toomuch light in Inner Detector(ID))• For such events, timing information of Outer
Detector (OD) hit clusters and ID was used totag “up-going”.
• From 52214 VHE SK-I events, 343 VHE “upgoing” candidates were selected. After scanning
1 candidate remains.

UHE upgoing µ candidate in SK-I

Total pecos θz (RA,DEC)

1804716. -0.63(20h38m,-37.3o)∆θ = 5 ~ 12deg

Limit on up-going VHE µν flux limit on up-going VHE µObserved events / 1496 day / 22.5 kton / 4 MeV

Here’s Where We Left Off…

102

10

1-1

10

20

30

40

50

60

7080
Energy (MeV)And Here’s How We
Constrained The Models…

SK-I relic ν spectrum and backgroundTotal background

90% CL limit

Atmospheric νµ →invisible µ → decay e
Atmospheric νeReal relic neutrino signalnνepe+

2.2MeV γ-ray∆T = ~ 200 µsec

またはGdCl4を溶かす？

No pre-activity
Very tiny post-activity with ∆T=~200µsec.
(trig. eff.=~1%)

Summary• SK-I upward going µ data has been further analyzed– No astrophysical sources found in high-energy showering up-µsample– No WIMP ν from Sun, Earth and Galactic center– No significant space/time ν clusters found in triggered SGR burst
search taken from BATSE catalog. ν fluence limits set.
– One up-µ found in coincidence with SGR burst, 0.96 expectedfrom atm. ν– No significant space/time ν clusters found in untriggered burst
search– one VHE up-going µ recovered from extremely energetic
saturated PMT data, consistent with atmospheric ν expectations
rather than a diffuse astrophysical signal•

SK-II ν of all energies not seen in coincidence with Dec.
2004 SGR 1806-20 outburst, ν fluence limits set

ν interaction @ ~10MeV
νe p  e+ n

νe e-  νe e-10-43 cm2

cos θsun Solar ν in Super-Kamiokande
1996 – 2001

22400 solar ν (~15/day)~170ev/day (non-solar ν BG)

Direction from the Sun

79.8x10-5 BGν/sec (Eν>7MeV)

Ring imaging Cherenkov
 ν+eν+eνElectronParticle ID for single ring ν event
Super-Kamiokande

Super-Kamiokande

Run 3013 Event 149004

Run 3062 Event 475360

96-10-24:19:39:51

96-11-08:12:07:30

Inner: 1763 hits, 4003 pE

Inner: 2305 hits, 7763 pE

Outer: 3 hits, 5 pE (in-time)

Outer: 5 hits, 4 pE (in-time)

Trigger ID: 0x03

Trigger ID: 0x03

D wall: 897.4 cm

D wall: 601.2 cm

FC e-like, p =FC mu-like, p = 1088.0 MeV/c

463.8 MeV/c

Time(ns)

Time(ns)< 958958- 963
963- 968
968- 973
973- 978978- 983
983- 988
988- 993
993- 998
998-1003
1003-1008
1008-1013
1013-1018
1018-1023
1023-1028
>1028

< 971
971- 977
977- 983
983- 989
989- 995
995-1001
1001-1007
1007-1013
1013-1019
1019-1025
1025-1031
1031-1037
1037-1043
1043-1049
1049-1055
>1055
550
0590
0

440
0

472
2

3300354
4

220
0

236
6

110
0

118
800

500

1000

1500

0

2000

0

Times (ns)e-like event (mostly CCννe)

500

1000

1500

Times (ns)µ-like event (mostly CCννµ)CC ντ (Eν>3.5GeV) looks multi ring2000

ν/cm2

Fluence limit for νµ1011νµ fluence limit (90 %CL)
atmospheric sample%
νµ ATM-FC

108105102

νµ ATM-PCνµ UPµ-1

1010-1110102

310Eν (GeV)ν/cm2Fluence limit for νe10νe fluence limit (90 %CL)
all sample%

11νe Solar
108105102

νe ATM-FC-1

1010-210-1

110Solar 領域でのanti νeはνeより２桁感度がよい

102310Eν (GeV)