The AMANDA-II Telescope- Status and First Results - The AMANDA-II Telescope

- Status and First Results -

Ralf Wischnewski / DESY-Zeuthenfor the

AMANDA Collaboration

ralf.wischnewski@desy.de

TAUP2001, September 2001, LNGS/Italy

HE ’ Telescopes …HE ’ Telescopes …

HE -Telescopes are still ”novel” instruments proving sensitivity to their primary channels

N X

e N e X from Astrophysical Sources ( Point / Diffuse )

calibration possible only with atmospheric ‘s

OutlineOutline

1. AMANDA-II Detector

2. Calibration of the AMANDA-B10 detector with Atmospheric ‘s Physics results from B10/1997, see A.Hallgren

3. Performance & Sensitivity of AMANDA-II

AMANDA-II Construction AMANDA-II Construction

1996 4 strings, coax transmission OMs

total 86 OMs AMANDA-B4

1997 +6 strings, twisted pair transmission OMs

total 302 OMs at 10 strings AMANDA-B10

1998 +3 strings, fiber transmission OMs

total 424 OMs AMANDA-B13

2000 +6 strings, fiber and digital transmission OMs

total 677 OMs at 19 strings AMANDA-II

2003-2008 ~80 strings with 60 OMs each, total 5000 OMs

ICECUBE

• 677 PMTs• 19 Strings• d = 200 m• h 500 m Vgeo1.6 107m3

AMANDA-II

(February 2000)

Trigger:• Majority >23 OM in <2.5 s• String Trigger

Atmospheric Muon BackgroundAtmospheric Muon Background

from atm.

from CR

Zenith of ‘s triggering AMANDA

-Signature: Upgoing muon

Background: Misreconstructed

atmospheric muons

Noise/Signal =

/

(atm) = 105…6

Maximum Likelihood ReconstructionMaximum Likelihood Reconstruction

Variation of track parameters until the spectrum of arrival times has highest Likelihood.Scattering results in a distance dependent time-delay relative to the Cherenkov cone.

Atmospheric -AnalysisAtmospheric -Analysis

• Two (largely) independent analyses were done

for the

1997 data set of Amanda-B10 with respect to

- methodical aspects (Cut definitions,

minim.functional)

- data cleaning (electronic noise ...)

• Used same signal & atmospheric muon

Background MC (BG-MC) and track model (ice

optics and single muon)

Analysis A: OverviewAnalysis A: Overview

• Conventional Likelihood description (no zenith

weight)

• Multi-photon Likelihood and hit-probabilities

• Background rejected by specific cuts: e.g. cascade fit for muon bremsstrahlung.

• Reject instrumental BG by hit-topology

• Cuts developed with emphasis on BG-MonteCarlo

• Deterministic method to define a small set of

final Cut parameters and their values ( CutEval)

Nevents bg sig S/N

Pre-processing : 1•109 0.95 0.951 : 2•105

Hit cleaning, Calibration ...

Level 1: 5•107 5•10-2

0.37 1 : 3•104

Fast track approximation (line fit)Simple up/down cut

Level 2: 4• 105 4•10-4

0.15 1 : 5•102

Time-likelihood reconstruction. Simple cuts (zenith,L,Ndir)

Level 3: 1• 104 1•10-5

0.07 1 : 30First cut optimization. Full likelihood reconstruction.

Level 4: 223 2•10-8 0.0410 : 1

Final Neutrino Cuts (CutEval)

Neutrino Analysis Chain (A)

Neutrino Analysis Chain (A)

Analysis A: Neutrino Cuts & Sample Size

Analysis A: Neutrino Cuts & Sample Size

Sample Quality, QSample Quality, Q

Define „Define „Sample Sample QualityQuality“:“:

Q = -log (NQ = -log (NBG BG /N/NTLTL))

Find (minimum) set of Cut-Variables, which optimize the signal to background efficiency

Data BG-MC

Sig-MC

Neutrino Events – Neutrino Events – StatisticsStatistics

Neutrino Events – Neutrino Events – StatisticsStatistics

Analysis A Analysis B Overlap Combined

Experiment 223 204 102 325-MC (stand) 378 265 119 524-MC (new) 237 - - -Background 10% 10% - -

130.1 days live time

Systematic UncertaintiesSystematic Uncertainties

Calibration

TimeGeometryAmplitudeOM sensitivity

Bulk IceVertical structuresHole Ice

Optical properties

Physics-prop./light yield-flux-oscillations

± 30 %

± 20 %

-20 %

± 10 %

± 10 %

< 5 %

- 5 %

-5 %

-50 %

-20 %

- Luminosity versus day in 1997

- Luminosity versus day in 1997

Number of Neutrino events and total number of Number of Neutrino events and total number of triggers in 1997triggers in 1997(analysis A). Total (analysis A). Total live time live time waswas 130.1 130.1 days. days.

Neu

trin

o c

an

did

ate

s

Nb

. of

trig

ger

(M

ill.

)

Zenith angle distributionZenith angle distribution

Analysis A

Cos(zenith)

Even

ts /

130d

/0.1

Energy distributionEnergy distribution

10 GeV 100 GeV 1000 GeV

(MC)

E ~ .07–3.4 TeV

Celestial distributionCelestial distribution

Combined sample325 events

130.1 days live-timePointing: 3ª - 4ª No clustering

Oscillations:Zenith dependence

Oscillations:Zenith dependence

(MC)

Cos(zenith) Cos(zenith)

Even

ts /

130d

/0.0

5

Rati

o O

sci/

No o

scci

Oscillations: Neutrino Energy

Oscillations: Neutrino Energy

(MC)

Summary: B-10 atmosph. ’s

Summary: B-10 atmosph. ’s

•The AMANDA-B data from 1997 (130.1 days live time) have been analysed for neutrino induced events

• 2 independent analyses find a total of 325 neutrino events with less than 10% background contamination

• Results are consistent with the MC expectation for background (atmospheric muons) and signal (atmospheric neutrinos) within (still relatively large) systematic uncertainties

• Improvement expected from - better local ice-properties & OM sensitivity calibration - improved MC light tracing & HE muon light yield

•AMANDA has reached „design luminosity“ !

•Larger effective area by 9 more strings (>double OMs)

•New technologies - improved timing - MultiHit resolution (muon bundles & HE events) - reduced electronic noise - Upgrade: full waveform sampling (FADCs) in 2002

•Triggering - HE events by majority trigger - E<100 GeV by string trigger - EAS-Array (SPASE) as efficient veto for UHE events

•Improved angular sensitivity range; resolution ~ 2 degrees

Amanda-II Amanda-II

•Amanda-II analysis for 2000 started in spring 2001 (1.2 TB Data back from Spole)

•Neutrino Analysis profits substantially from Amanda-B10 analysis. Tuning to new geometry and hardware is under way.

•Minimum bias and low neutrino-cut level data look ok vs. MC.

•MC-results given below for „final AM-II neutrino cuts“ (Aeff, ,...) are still preliminary.

Amanda-II Amanda-II

Amanda-II: Detector response

Amanda-II: Detector response

Number of hit Optical Modules

Inner Strings (1-10)

All Strings (1-19)

Outer Strings (11-19)

Data - dotsMC - line

Amanda-II: Detector response

Amanda-II: Detector response

Minimum bias Zenith & Azimuth acceptance

Event Rates: ande Event Rates: ande

Trigger Level

Atmospheric

- 11000 (CC)

- 130 (NC)

e - 160 (CC)

- 9 (NC)

AGN (E-2 10-6 GeVcm- 2s- 1sr-1 )

- 853 (CC)

e - 103 (CC)

e

ATM

AGN

Atmospheric MC: Energy

responseAtmospheric

MC: Energy response

After BGrejection

Aeff(E) much improved compared to AMANDA-B10

Trigger Level

Atmosph. MC: Angular Sensitivity

Atmosph.

MC: Angular Sensitivity

TriggerLevel

After BGrejection

up horizon

Nearly uniform angular sensitivity to horizon

~200 atm per angular bin & livetime-year

AMANDA-II:a

horizontal event

AMANDA-II:a

horizontal event

( preliminary Am-II neutrino- cuts )

Am-II: Effective Area vs zenith

Am-II: Effective Area vs zenith

0

50

100

150

200

-1 -0.8 -0.6 -0.4 -0.2 0

Ae

ff

[ x1

03 m

2]

Cos(theta)

E = 10 TeV

Am-II Trigger

Am-II Point Cuts

Am-B10 Point Cuts

Am-II GRB Cuts

Aeff depends sensitively on the physics objective!

Point source sensitivity is uniform to near horizon

Amanda-II - Effective Volume

Amanda-II - Effective Volume

0.1

0.3

0.5

101 102 103

<V

eff >

(k

m3)

E (TeV)

Veff () is0.3-0.5 km3

•R > 10 km

(for Point Source Cuts)

Diffuse Flux Diffuse Flux

10-10

10-8

10-6

10-4

10-2

103 104 105 106 107

E2 (d

N/d

E )

[G

eVcm

-2s

-1sr

-1]

E(GeV)

AMANDA-II (3 yr)

AMANDA-B10 ('97)

IceCube

3C273

AGN Core

Atm.

AGN Core

Convolved energy resolution

New techniques

Anticipated sensitivity

AMANDA-II Anticipated sensitivity

Upper Bounds on Diffuse Flux

Upper Bounds on Diffuse Flux

Baikal NT-200

Point SourcesPoint Sources

10-10

10-8

10-6

10-4

102 103 104 105 106

E2 (d

N/d

E )

[G

eVcm

-2s

-1]

E(GeV)

AMANDA-II (3 yr)

AMANDA-B10 ('97)

IceCube3C273

Crab

AGN Core

Mk501 (=)

Atm.

Atmospheric + energy resolution

Point Sources Point Sources

10-10

10-8

10-6

10-4

102 103 104 105 106

E2 (d

N/d

E )

[G

eVcm

-2s

-1]

E(GeV)

AMANDA-II (3 yr)

AMANDA-B10 ('97)

IceCube3C273

Crab

AGN Core

Mk501 (=)

Atm.

Focus onMk501 asexample

• Earth shadowing of ‘s becomes relevant for PeV

•Horizontal and „downgoing“ events dominate

• New search strategies under development

- Total energy cuts & Energy flow vs. track reconstruction

- EAS-Veto by surface Array SPASE

UHE events UHE events

Downgoing -induced MuonFlux

Downgoing -induced MuonFlux

10-16

10-14

10-12

10-10

10-8

107 108 109 1010 1011 1012 1013 1014

Downgoing Muon Flux in AMANDA-B

with Eth

=106GeV

F,10^14F,GelF,ProthF,SteckF,p-gammaF,ZBurstF,pi-KF,pQCDF,SM

E (GeV)

TD MX=10

14, p=1

Gelmini & Kusenko (00)AGN (Protheroe 97)AGN (Stecker et al 96)p

ZBurst

, K-muonsCharm (pQCD)Charm (SM)

AttenuationArea(E,theta)Filt 120

AMANDA B10 Sensitivity

Angular distributionAngular distribution

10-4

10-3

10-2

10-1

100

101

102

-1 -0.5 0 0.5 1

cos()

AGN (Protheroe)GZK*100

DownUp

Most events are horizontal.

EeV sources cut offvery quickly belowhorizon.

Direction providesadditional BG reject.

Summary Summary

•AMANDA-B10 Final Analysis (1997) yields 325 HE neutrino events The first high statistics -event sample for an UWater/Uice Telescope Proof of principle of operation in Antarctic scattering ice. •AMANDA-II

>105 m2 Trigger Area - the Largest Muon and Neutrino Telescope ever built. Improved performance compared to B10-Telescope Horizontal Angular acceptance

Event rates of 4-5 atm. ‘s per livetime day, 800-1000 ‘s for year-2000.