diffuse high-energy neutrino searches in amanda-ii and
TRANSCRIPT
Kotoyo Hoshinafor IceCube Collaboration
TAUP 2007 in Sendai
Diffuse high-energy neutrino searches in AMANDA-II and IceCube 9 strings
Event Detection Strategy Cosmic Ray
Cosmic RayAstrophysical
Neutrino (signal)
Muon
Atmospheric Neutrino
µνµπ +→ ++
µνν +++ee
(similar for )±− K,π
•Target neutrinos :
•Detect muons generated from neutrinos via Charged Current interaction
•Choose up going events to reject atmospheric muons(apply quality cuts)
θ
down going
up going
★
Ice
Cherenkov radiation
Digital Optical Module (DOM) for IceCube
Detection Mechanism
Observables
• Hit timing (Direct Hit, Hit)
• Number of Hit OMs (Nch)• Charge / waveform
Direct Hit
Hit
Used for track reconstruction,Number of Direct Hit (Ndir) indicates reconstruction quality
Used as energy estimatorwaveform can be used for trackreconstruction (not this analysis)
What is Diffuse Neutrino Search ?
• If individual neutrino sources are too faint...
• Still possible to investigate overall feature of isotropically distributed sources
• If astrophysical neutrinos follow harder energy spectrum than backgrounds...
Investigate energy-relatedobservable to search forastrophysical neutrinos!
Nch0 20 40 60 80 100
-110
1
10
210 Atmospheric Nu
Astrophysical Nu
)-2
(test flux: 1.0e-6 E
All Monte-Carlo
Energy[GeV])µ!(true 10
Log0 1 2 3 4 5 6 7 8 9
Arb
itra
ry U
nit
0
50
100
150
200
250
300
350
Atmospheric Nu
Astrophysical Nu
)-2
(test flux 1.0e-6 E
All Monte-Carlo
Analysis Strategy
Signal spectrum is harder than Atms.Neutrino
Nch
True NeutrinoEnergy Distribution
(not observable)
Number of Hit OMs (Nch)(observable)
count event aboveNch > Nchcut
i. Reject all background muons then Search best Nchcut
ii.Apply Nch cut (Nch>Nchcut) thencompare number of survived events with Monte-Carlo prediction
Nchcut
Data 2000 - 2003
!Uncertainty in atms.
!Barr et al. atms.
!Honda et al. atms.
!CORSIKA atms.
-1 sr-1 s-2 GeV cm-6 = 10sig"2E
Data 2000 - 2003
!Uncertainty in atms.
!Barr et al. atms.
!Honda et al. atms.
!CORSIKA atms.
-1 sr-1 s-2 GeV cm-6
= 10sig"2E
Data 2000 - 2003
!Uncertainty in atms.
!Barr et al. atms.
!Honda et al. atms.
!CORSIKA atms.
-1 sr-1 s-2 GeV cm-6 = 10sig"2E
Data 2000 - 2003
!Uncertainty in atms.
!Barr et al. atms.
!Honda et al. atms.
!CORSIKA atms.
-1 sr-1 s-2 GeV cm-6
= 10sig"2E
Cosine of Reconstructed Zenith Angle-1 -0.8 -0.6 -0.4 -0.2 -0
Even
ts
-210
-110
1
10
210
310
410
horizontal
events
removed
level of final analysis
level 5
Cosine of Reconstructed Zenith Angle-1 -0.8 -0.6 -0.4 -0.2 -0
Even
ts
-210
-110
1
10
210
310
410
• Require enough number of Direct Hit which close to the expected hit time for the reconstructed track (Ndir cut)
• Hits should distribute smoothly along with the reconstructed track
• Require long enough track
• Remove horizontal events
Event selection : Preparing neutrino induced eventsQuality cuts (examples)
upgoing horizontal
Data (Nch < 100)
AMANDA-II 807days Diffuse AnalysisNch distribution after final selection
)ch
Number of OMs hit (N
0 20 40 60 80 100 120 140 160
Even
ts
-210
-110
1
10
210
Data 2000 - 2003
!Uncertainty in atmospheric
! + prompt !Barr et al. atms.
! + prompt !Honda et al. atms. -1sr-1s-2 GeV cm
-6 = 1.0 x 10
signal"2E
-1sr-1s-2 GeV cm-8
= 7.4 x 10signal"2E
final event sample
rescaled!atms.
at Nch > 100, 6 events observedno significant excess from background
(GeV)]!
[E10
log3 4 5 6 7 8 9
]-1
sr
-1 s
-2 d
N/d
E [
GeV
cm
2E
-910
-810
-710
-610
-510
-410 data (prelim.)!!AMANDA-II 2000 atms.
! + prompt atms. !Barr et al. atms.
! + prompt atms. !Honda et al. atms.
!Max uncertainty in atms.
Frejus
MACRO
diffuse!!AMANDA B-10 1997
AMANDA-II 2000 Cascades (all-flavor / 3)*
AMANDA B-10 1997 UHE (all-flavor / 3)*
Baikal 1998 - 2002 ( all-flavor / 3 )*
RICE 1999-2005 ( all-flavor / 3 )*
AMANDA-II 2000 unfolding (prelim.)
AMANDA-II 2000-2002 UHE limit (prelim.)
limit!!AMANDA-II 2000-3
W&B limit/2 (transparent sources)
Full IceCube 1 yr
* assumes a 1:1:1 flavor ratio at Earth
AMANDA-II 807days Diffuse AnalysisUpper Limit
E-2 < 7.4 x 10-8 GeV cm-2 s-1 sr-1
Paper Published!Physical Review D 76,
042008 (2007)
IceCube 9 strings
137days analysis
-200
-100
0
100
200
200 300 400 500 600
xIceCube [m]
yIc
eC
ub
e [m
]
1
2
345
6 7
8
9 10
1112
13
14
15
16 17
18
19
21DL1
29
30
38 39
40SC1
49
50DL2
59
BC
~125m
IceCubeAmanda
/GeV)ν (E10
Log2 3 4 5 6 7 8
]2
are
a [
cm
νE
ffe
cti
ve
210
310
410
510
610
710
After final event selection
-0.8 > cos(true zenith) >= -1.0
-0.6 > cos(true zenith) >= -0.8
-0.4 > cos(true zenith) >= -0.6
-0.2 > cos(true zenith) >= -0.4
0.0 > cos(true zenith) >= -0.2
0.2 > cos(true zenith) >= 0.0
• 3~4 times larger detector volume • 3~4 times wider string intervals
IceCube 9 (IC9) vs AMANDA
Muon NeutrinoEffective Area(after Nch cut)
1km
250m 375m
500m
1m2
IC9Amanda
200m2~4 times larger effective area (105 ~ 106GeV)
90% energy range shifts to higher energy
Log10(primary Nu energy [GeV])2 3 4 5 6 7 8
-210
-110
1
10
210
310
410
Atms.Nu before Nch cut
Nu before Nch cut-21e-6xE
Atms.Nu after Nch cut
Nu after Nch cut-21e-6xE
90% signal region
True Neutrinoenergy
Amanda 90% signal reg.
CosZenith
-1 -0.8 -0.6 -0.4 -0.2 0 0.2
-110
1
10
210
CosZenith
-1 -0.8 -0.6 -0.4 -0.2 0 0.2
1
10
210
310
410
Event selection : Preparing neutrino induced eventsData Nch < 46 is already unblinded for Atms.Nu study
(see P.Desiati’s talk on Thursday)
Data + Atms. Mu+ Double Mu+ Atms. Nu+1e-6 E-2 Nu
after angle resolution cut
after Ndir cut after final cutCosZenith
-1 -0.8 -0.6 -0.4 -0.2 0 0.2
1
10
210
Number of event after final cut (Nch<46)
preliminary
Data : 52 eventAll background MC : 60 + 5 event
Nch distribution After final selection
Nch0 20 40 60 80 100 120 140 160 180 200
-110
1
10 Atms. Neutrino MC
Signal Neutrino MC
)-2
(test flux 1e-6 E
mrfEntries 150
Mean 77.97
RMS 37.46
Nch0 20 40 60 80 100 120
0.2
0.4
0.6
0.8
1
mrfEntries 150
Mean 77.97
RMS 37.46Best mrf(bottom) = 0.126009
Best cut at Nch=33 (bin 17)
Best Integrated Bgd = 4.79439
Int. Bgd (<bestcut) = 61.4359
Best Integrated Sig = 40.5372 ---------------------------------
mrf at cut = 0.129037 Cut Nch=46 (bin 24)
Best Integrated Bgd = 1.06569
Int. Bgd (<cut) = 60.625
Best Integrated Sig = 25.7652
Model Rejection Factor
IceCube 9 string ~ 137daysScale factor of test flux vs Nch cut threshold
Min. 0.13
Nchcut = 46
• Scale factor is very flat between Nchcut ~30 and 50
ChooseNchcut = 46
to get sensitivity
(GeV)]!
[E10
log3 4 5 6 7 8 9
]-1
sr
-1 s
-2 d
N/d
E [
Ge
V c
m2
E
-910
-810
-710
-610
-510
-410 data (prelim.)µ!AMANDA-II 2000 atms.
! + prompt atms. !Barr et al. atms.
! + prompt atms. !Honda et al. atms.
!Max uncertainty in atms.
Frejus
MACRO
diffuseµ!AMANDA B-10 1997
AMANDA-II 2000 Cascades (all-flavor / 3)*
AMANDA B-10 1997 UHE (all-flavor / 3)*
Baikal 1998 - 2002 ( all-flavor / 3 )*
RICE 1999-2005 ( all-flavor / 3 )*
AMANDA-II 2000 unfolding (prelim.)
AMANDA-II 2000-2002 UHE limit (prelim.)
limitµ!AMANDA-II 2000-3
W&B limit/2 (transparent sources)
Full IceCube 1 yr
* assumes a 1:1:1 flavor ratio at Earth
IceCube 9 strings 137days
Diffuse Muon Neutrino Sensitivity of IC9 137 days (2006)
AMANDA-II807days upper limit
E-2 < 1.3 x 10-7 GeV cm-2 s-1 sr-1
IC9 137days sensitivity is factor 2 above AMANDA-II 807daysin 2007 integrated IceCube exposure exceeds AMANDA-II 4yr
• AMANDA-II 807days upper limit on the diffuse flux of muon neutrino with a AconstE-2 spectrum for the energy range 16 TeV to 2.5PeV is
• Monte-Carlo verification for IceCube 9 string has done with Nch<46 low energy data. MC data shows reasonable agreement with the data sample.
• The sensitivity of IceCube 9 string 137days for the energy range from 40TeV to 20PeV is
which is factor 2 above AMANDA-II 807days.
E-2 < 7.4 x 10-8 GeV cm-2 s-1 sr-1
E-2 < 1.3 x 10-7 GeV cm-2 s-1 sr-1
Summary
Outlook IceCube-22 with AMANDA
-200
-100
0
100
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300
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600
0 100 200 300 400 500 600
xIceCube [m]
yIc
eC
ub
e [m
]
1
2
345
6 7
8
9 10
1112
13
14
15
16 17
18
19
21DL1
29
30
38 39
40SC1
49
50DL2
59
46
47 48
5657
BC
58
6566
rDL
67
7273
74
78
ice flow
Grid N
ort
h
Analyses for 22 string is now in preparation
Physics run of IceCube 22 started in 5/23
• Detector Volume : x 2~3 of IC9
• Accumulted Livetime :~3month by now