Diffuse high-energy neutrino searches in AMANDA-II and IceCube 9 - - PowerPoint PPT Presentation

SLIDE 1

Kotoyo Hoshina for the IceCube Collaboration TAUP 2007 in Sendai

Diffuse high-energy neutrino searches in AMANDA-II and IceCube 9 strings

SLIDE 2

Event Detection Strategy Cosmic Ray Cosmic Ray Astrophysical Neutrino (signal) Muon Atmospheric Neutrino

µ

ν µ π + →

+ +

µ

ν ν + +

+ e

e

(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

★

SLIDE 3

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 estimator waveform can be used for track reconstruction (not this analysis)

SLIDE 4

What is Diffuse Neutrino Search ?

• Astrophysical point source search

(See T.Montaruli’s talk in this session)

• Observe multiple events from same source
• Needs good angle resolution
• Atmospheric Neutrino study

(see P .Desiati’s talk on Thursday)

• Uses low energy sample
• Need statistics
• Diffuse high-energy source search
• Uses energy-related parameter to

investigate excess from Atmospheric Neutrino events

• Event selection : optimized to extract

high-energy sample fewer Atmospheric Neutrino event in final sample

SLIDE 5

Nch 20 40 60 80 100

• 1

10 1 10

2

10

Atmospheric Nu Astrophysical Nu )

• 2

(test flux: 1.0e-6 E All Monte-Carlo

Energy[GeV])

µ

• (true

10

Log 1 2 3 4 5 6 7 8 9

Arbitrary Unit

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 Neutrino Energy Distribution (not observable) Number of Hit OMs (Nch) (observable)

count event above Nch > Nchcut

• i. Reject all background muons then Search best Nchcut

ii.Apply Nch cut (Nch>Nchcut) then compare number of survived events with Monte-Carlo prediction

Nchcut

SLIDE 6

AMANDA-II

807days multi-year analysis

1500m 500m 200m 677 OMs

SLIDE 7

Data 2000 - 2003 ! Uncertainty in atms. ! Barr et al. atms. ! Honda et al. atms. ! CORSIKA atms.

• 1

sr

• 1

s

• 2

GeV cm

• 6

= 10

sig

"

2

E

Data 2000 - 2003 ! Uncertainty in atms. ! Barr et al. atms. ! Honda et al. atms. ! CORSIKA atms.

• 1

sr

• 1

s

• 2

GeV cm

• 6

= 10

sig

"

2

E

Data 2000 - 2003 ! Uncertainty in atms. ! Barr et al. atms. ! Honda et al. atms. ! CORSIKA atms.

• 1

sr

• 1

s

• 2

GeV cm

• 6

= 10

sig

"

2

E

Data 2000 - 2003 ! Uncertainty in atms. ! Barr et al. atms. ! Honda et al. atms. ! CORSIKA atms.

• 1

sr

• 1

s

• 2

GeV cm

• 6

= 10

sig

"

2

E

Cosine of Reconstructed Zenith Angle

• 1
• 0.8
• 0.6
• 0.4
• 0.2

Events

• 2

10

• 1

10 1 10

2

10

3

10

4

10

horizontal

events

removed

level of final analysis

level 5

Cosine of Reconstructed Zenith Angle

• 1
• 0.8
• 0.6
• 0.4
• 0.2

Events

• 2

10

• 1

10 1 10

2

10

3

10

4

10

• 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 events Quality cuts (examples) upgoing horizontal

Data (Nch < 100)

SLIDE 8

AMANDA-II 807days Diffuse Analysis Nch distribution after final selection

)

ch

Number of OMs hit (N 20 40 60 80 100 120 140 160 Events

• 2

10

• 1

10 1 10

2

10

Data 2000 - 2003 ! Uncertainty in atmospheric ! + prompt ! Barr et al. atms. ! + prompt ! Honda et al. atms.

• 1

sr

• 1

s

• 2

GeV cm

• 6

= 1.0 x 10

signal

"

2

E

• 1

sr

• 1

s

• 2

GeV cm

• 8

= 7.4 x 10

signal

"

2

E

final event sample

rescaled ! atms.

at Nch > 100, 6 events observed no significant excess from background

SLIDE 9

(GeV)]

!

[E

10

log 3 4 5 6 7 8 9 ]

• 1

sr

• 1

s

• 2

dN/dE [GeV cm

2

E

• 9

10

• 8

10

• 7

10

• 6

10

• 5

10

• 4

10

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 Analysis Upper Limit

E-2 < 7.4 x 10-8 GeV cm-2 s-1 sr-1

Paper Published! Physical Review D 76, 042008 (2007)

SLIDE 10

IceCube 9 strings

137days analysis

• 200
• 100

100 200 200 300 400 500 600

xIceCube [m] yIceCube [m]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

21

DL1

29 30 38 39 40

SC1

49 50

DL2

59

BC

~125m IceCube Amanda 540 DOMs (IC9)

SLIDE 11

/GeV)

ν

(E

10

Log 2 3 4 5 6 7 8 ]

2

area [cm ν Effective

2

10

3

10

4

10

5

10

6

10

7

10

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
• Similar number of Optical Sensors

IceCube 9 (IC9) vs AMANDA

Muon Neutrino Effective Area (after Nch cut)

1km 250m 375m 500m

1m2

IC9 Amanda

200m

2~4 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

• 2

10

• 1

10 1 10

2

10

3

10

4

10 Atms.Nu before Nch cut Nu before Nch cut

• 2

1e-6xE Atms.Nu after Nch cut Nu after Nch cut

• 2

1e-6xE 90% signal region

True Neutrino energy

Amanda 90% signal reg.

SLIDE 12

CosZenith

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2

• 1

10 1 10

2

10 CosZenith

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 1 10

2

10

3

10

4

10

Event selection : Preparing neutrino induced events Data Nch < 46 is already unblinded for Atms.Nu study

Data + Atms. Mu + Double Mu + Atms. Nu +1e-6 E-2 Nu after angle resolution cut after Ndir cut after final cut

CosZenith

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 1 10

2

10

Number of event after final cut (Nch<46)

preliminary Data : 52 event Background MC : 60 + 5 (Bartol) (54 + 4 : Honda 2006) Low Nch data sample is compared with MC

SLIDE 13

Nch distribution After final selection

Nch 20 40 60 80 100 120 140 160 180 200

• 1

10 1 10

• Atms. Neutrino MC

Signal Neutrino MC )

• 2

(test flux 1e-6 E

SLIDE 14

mrf

Entries 150 Mean 77.97 RMS 37.46

Nch 20 40 60 80 100 120 0.2 0.4 0.6 0.8 1

mrf

Entries 150 Mean 77.97 RMS 37.46

Best 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 ~ 137days Scale factor of test flux vs Nch cut threshold

• Min. 0.13

Nchcut = 46

• Scale factor is

very flat between Nchcut ~30 and 50 Choose Nchcut = 46 to get sensitivity

SLIDE 15

(GeV)]

• [E

10

log 3 4 5 6 7 8 9 ]

• 1

sr

• 1

s

• 2

dN/dE [GeV cm

2

E

• 9

10

• 8

10

• 7

10

• 6

10

• 5

10

• 4

10

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 diffuse

µ

• 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

µ

• 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-II 807days 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 807days in 2007 integrated IceCube exposure exceeds AMANDA-II 4yr

SLIDE 16

• 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 on the diffuse

flux of muon neutrino with a AconstE-2 spectrum for the energy range from 25T eV to 10PeV 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

SLIDE 17

Outlook

IceCube-22 with AMANDA

• 200
• 100

100 200 300 400 500 600 100 200 300 400 500 600

xIceCube [m] yIceCube [m]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

21

DL1

29 30 38 39 40

SC1

49 50

DL2

59 46 47 48 56 57

BC

58 65 66

rDL

67 72 73 74 78

ice flow Grid North

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

SLIDE 18

• Backup slides

SLIDE 19

/GeV)

!

(E

10

Log 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 )

2

area (cm ! Effective

• 2

10

• 1

10 1 10

2

10

3

10

4

10

5

10

6

10

• 1.0 < cos(True Zenith) < -0.8
• 0.8 < cos(True Zenith) < -0.6
• 0.6 < cos(True Zenith) < -0.4
• 0.4 < cos(True Zenith) < -0.17

all angle

AMANDA effective area

SLIDE 20

hData_Azimuth_L4

Entries 1.039091e+07 Mean 171.3 RMS 102.8

Azimuth 50 100 150 200 250 300 350 50 100 150 200

3

10 ×

hData_Azimuth_L4

Entries 1.039091e+07 Mean 171.3 RMS 102.8

hData_Azimuth_L4 hCorsika_Azimuth_L4 hDoubleMu_Azimuth_L4 hAtmNu_Azimuth_L4 hSigNu_Azimuth_L4

hData_Azimuth_L4

hData_Azimuth_L5

Entries 117679 Mean 160.6 RMS 97.6

Azimuth 50 100 150 200 250 300 350 1000 2000 3000 4000 5000 6000

hData_Azimuth_L5

Entries 117679 Mean 160.6 RMS 97.6

hData_Azimuth_L5 hCorsika_Azimuth_L5 hDoubleMu_Azimuth_L5 hAtmNu_Azimuth_L5 hSigNu_Azimuth_L5

hData_Azimuth_L5

hData_Azimuth_L6

Entries 503 Mean 163.6 RMS 95.27

Azimuth 50 100 150 200 250 300 350 20 40 60 80 100 120 140 160

hData_Azimuth_L6

Entries 503 Mean 163.6 RMS 95.27 hData_Azimuth_L6 hCorsika_Azimuth_L6 hDoubleMu_Azimuth_L6 hAtmNu_Azimuth_L6 hSigNu_Azimuth_L6

hData_Azimuth_L6

hData_Azimuth_L7

Entries 52 Mean 169.3 RMS 110

Azimuth 50 100 150 200 250 300 350 1 2 3 4 5 6 7

hData_Azimuth_L7

Entries 52 Mean 169.3 RMS 110

hData_Azimuth_L7 hCorsika_Azimuth_L7 hDoubleMu_Azimuth_L7 hAtmNu_Azimuth_L7 hSigNu_Azimuth_L7

hData_Azimuth_L7

Azimuth distribution

SLIDE 21

Atms.Nu model difference Bartol Honda (2006)

SLIDE 22

HitDistance vs CosZenith