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First Results from IceCube
Physics Motivation
Hardware Overview
Deployment
First Results
Conclusions & Future Plans
Spencer Klein, LBNLfor the IceCube Collaboration
See Paolo Desiati’s AMANDA talk
S. Klein, LBNL
USA (12)USA (12)
Europe (12)Europe (12)JapanJapan
New ZealandNew Zealand
• Alabama University, USA• Bartol Research Institute, Delaware, USA• Pennsylvania State University, USA• UC Berkeley, USA• UC Irvine, USA• Clark-Atlanta University, USA• Univ. of Maryland, USA
• Alabama University, USA• Bartol Research Institute, Delaware, USA• Pennsylvania State University, USA• UC Berkeley, USA• UC Irvine, USA• Clark-Atlanta University, USA• Univ. of Maryland, USA
• IAS, Princeton, USA• University of Wisconsin-Madison, USA• University of Wisconsin-River Falls, USA• LBNL, Berkeley, USA• University of Kansas, USA• Southern University and A&M College, Baton Rouge, USA
• IAS, Princeton, USA• University of Wisconsin-Madison, USA• University of Wisconsin-River Falls, USA• LBNL, Berkeley, USA• University of Kansas, USA• Southern University and A&M College, Baton Rouge, USA
• Universite Libre de Bruxelles, Belgium• Vrije Universiteit Brussel, Belgium• Université de Mons-Hainaut, Belgium• Universiteit Gent, Belgium• Humboldt Universität, Germany• Universität Mainz, Germany• DESY Zeuthen, Germany• Universität Dortmund, Germany
• Universite Libre de Bruxelles, Belgium• Vrije Universiteit Brussel, Belgium• Université de Mons-Hainaut, Belgium• Universiteit Gent, Belgium• Humboldt Universität, Germany• Universität Mainz, Germany• DESY Zeuthen, Germany• Universität Dortmund, Germany
• Universität Wuppertal, Germany• Kalmar university, Sweden,• Uppsala university, Sweden• Stockholm university, Sweden• Imperial College, London, UK• Oxford university, UK• Utrecht university, Netherlands
• Universität Wuppertal, Germany• Kalmar university, Sweden,• Uppsala university, Sweden• Stockholm university, Sweden• Imperial College, London, UK• Oxford university, UK• Utrecht university, Netherlands
• Chiba university, Japan• University of Canterbury, Christchurch, NZ
• Chiba university, Japan• University of Canterbury, Christchurch, NZ
ANTARCTICA
The IceCube Collaboration
S. Klein, LBNL
Physics Motivation Search for cosmic-ray accelerators
Protons are bent in galactic magnetic fields
are produced by hadron accelerators
HE (>5*1013 eV) photons are absorbed by interaction with 30K microwave background photons --> e+e-
Study the High-Energy Universe ~100 GeV – 1019 eV
Cross section & effective area rise with energy, so a single detector can cover a very wide energy range
S. Klein, LBNL
Physics Topics Source searches
Active Galactic Nuclei Supernova remnants Gamma-Ray Bursts Calculations predict 1-10 /km3/year from many
source models Neutrino physics
Expect 100,000 atmospheric /year Cross-section measurements
Absorption in earth Decoherence Oscillations
Searches for supersymmetry, WIMPs, MeV from supernovae, monopoles, Q-balls….
Crab Nebula
Active Galactic Nucleus
S. Klein, LBNL
Detector Requirements
Need 1 km3 area for a good chance to see signals
Requires a natural material Ice or water
South Pole Ice has Long absorption length Shorter scattering length
Depth dependent Low dark noise rates
Ice model:Scattering vs. wavelength and depth
S. Klein, LBNL
Lessons from AMANDA AMANDA pioneered astronomy at the
South pole Deployed first OMs 1993/4
Observed atmospheric
Deep ice (> 1 km) has good optical qualities
Data transmission to surface nontrivial Paolo Desiati’s talk will present
AMANDA results
A muon inAMANDA
S. Klein, LBNL
1 gigaton instrumented volume 80 strings of 60 digital optical modules
1450-2450 m deep 17 m spacing
125 m hexagonal grid Each DOM is an autonomous data
collection unit IceTop air shower array
160 surface water tanks Each contains 2 DOMs
AMANDA
String 21
IceCube
1 string + 8 tanks deployed Jan. 2005
S. Klein, LBNL
, e and IceCube will distinguish , e and based on the event characteristics
--> produce long muon tracks Good angular resolution, limited energy resolution Atmospheric are a significant background to searches for extra-terrestrial
• Soft energy spectra --> may improve signal to noise ratio by optimizing for higher energy
e --> e produce EM showers Good energy resolution, poor angular resolution
Above ~1016 eVproduce ‘double-bang’ events One shower when the is created, another when it decays
S. Klein, LBNL
Eµ=6 PeV, 1000 hitsEµ=10 TeV, 90 hits
Simulated Events
S. Klein, LBNL
A e would appearas a single shower
n.b. c=300 m forE = 6 TeV
A simulated multi-Pev event
S. Klein, LBNL
Digital Optical Module
main board
LED flasher board
PMT base
25 cm PMT33 cm Benthosphere
Hardware
S. Klein, LBNL
Analog Front-End Want to measure arrival time of every photon 2 waveform digitizer systems
200-700 Megasamples/s, 10-bit switched capacitor array 3 parallel digitizers give 14 bits of dynamic
range 128 samples --> 400 nsec range Dual chips to minimize dead-time
40 Megasamples/s, 10-bit ADC 256 samples --> 6.4 s range
Self-triggered Also, ‘local-coincidence’ circuitry looks for hits in
nearby modules
An ATWD waveform
Time bin (3.3 ns)
S. Klein, LBNL
DOM Readout
Each DOM is a ‘mini-satellite’ FGPA + ARM7 CPU for control,
data compression… Packetized data is sent to surface Baseline data transmission
waveforms for local coincidence data Rate ~ 15-30 Hz
timing and charge info for isolated hits Rate ~ 700 Hz
‘Rapcal’ timing calibration maintains clock calibration to < 2 nsec
A ‘Main Board’
S. Klein, LBNL
Surface DAQ Trigger based on multiplicity &
topology (in a sliding time window) Selected data saved to tape High-priority data sent north over a
satellite link GPS clock for overall timing
S. Klein, LBNL
Amundsen-Scott South Pole station
South PoleDome (old station)
“Summer camp”
road to work
IceCube
Skiway
http://icecube.wisc.edu
AMANDA
S. Klein, LBNL
The drilling site in January, 2005
Hot-water drilling
Hose reel Drill tower
IceTop tanksHot water generator
S. Klein, LBNL
The 5 MW water heaterfor the hot water drill
(car-wash technology)
Hose Reel
S. Klein, LBNL
Each 2 m dia. IceTop tank contains two DOMs.
An IceTop tank
signals from IceTop DOMs
S. Klein, LBNL
Schedule & Logistics Can work December --> mid-February Logistics are a huge concern
Freight, power, … are expensive! Weather is always a factor
The new South-Pole station
S. Klein, LBNL
27.1, 10:08: Reached maximum depth of 2517 m28.1, 7:00: preparations for string installation start9:15: Started installation of the first DOM22:36: last DOM installed 12 min/DOM22:48: Start drop29.1, 1:31: String secured at depth of 2450.80 20:40: First communication to DOM
IceCube’s First String: January 28, 2005
S. Klein, LBNL
2 high-multiplicity muon events
Tim
e R
esid
ual (
ns)
Tim
e R
esid
ual (
ns)
Tim
e R
esid
ual (
ns)
Depth (m)
Depth (m)
S. Klein, LBNL
First Results from String 21
• Time calibration
• Muon reconstruction
• Timing verification with muons
• Timing and Energy measurement with LED flashers
• Coincidence events IceCube - IceTop
S. Klein, LBNL
Time Calibration
for 76 DOMs
Time IceTop
In-ice DOMs
IceTop
S. Klein, LBNL
Muon and Flasher Reconstruction
Observe Cherenkov radiation from charged particle tracks
Muons produce ~ km long tracks + hadronic shower at interaction point
EM cascades produce ~ point sources LED flashers are a surrogate for e
Reconstruct both with maximum likelihood techniques Use arrival times of all photons, as
determined from waveform information
~10m-long cascades, e neutral current
S. Klein, LBNL
Muon zenith angle distribution
S. Klein, LBNL
Timing studies with muons
The random and systematic time offsets from one DOM to the next are small, ≤ +/- 3ns
Re
sid
ual
Tim
ing
(n
s)
Sca
tteri
ng
(
1/m
)
S. Klein, LBNL
A flasher event
Equivalent to ~ 60 TeV e
Flasher
Color --> arrival time Circle size --> Amplitude
S. Klein, LBNL
Timing resolution from flashers
1.74 ns rms
All 60 DOMs
{Photon arrival time difference between DOM45 & 46
S. Klein, LBNL
Energy Measurement for flashers
Reconstruct energy of flash for each flashing DOM, using known position
Variation due to Ice models LED intensity Detector Response..
Good agreement across entire string
All LEDsSide LEDs450 LEDs~1/3 Intensity
S. Klein, LBNL
IceTop and in-ice coincidences
Some of the difference is due to shower curvature
S. Klein, LBNL
Conclusions & Outlook
IceCube will explore the high-energy sky. With a 1 km3 effective area, IceCube has the power to
observe extra-terrestrial neutrinos. We deployed our first string in January, 2005.
76 out of 76 DOMs are working well. Timing resolution is < 2 nsec
Next austral summer, we will deploy 8-12 more strings. Largest neutrino observatory in the world.
By 2010, we will have instrumented ~ 1 km3.
S. Klein, LBNL
Extras/Backup
IceCube reviewers – read no farther
S. Klein, LBNL
10” PMTHamatsu-70
S. Klein, LBNL
Muon Angular Resolution
Waveforminformationnot used.Will improveresolution for
high energies !
S. Klein, LBNL
Timing verification with light-flashers
Photons going up Photons going down
47