A km3 Neutrino Telescope: IceCube at the South Pole

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A km3 Neutrino Telescope IceCube at the South
Pole

• Howard Matis - LBNL
• for the IceCube Collaboration

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Neutrino Astronomymeasuring ns by its µ
Accelerator
Target

• Stable particles ???p, ?
• Astrophysical Sources
• GRB, AGN, Super Novae
• GZK (p CMB ?)
• Topological defects
• Backgrounds
• Atmospheric ?s
• Atmospheric ?s

Earth
IceCube
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IceCube

• IceCube is designed to detect neutrinos of all
  flavors at energies from 107 eV (SN) to 1020 eV
• 80 Strings
• 4800 PMT
• Instrumented volume 1 km3
• Depth 1400 m to 2400m

Amanda
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South Pole
Dark sector
Skiway
AMANDA
Dome
IceCube
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Detecting ns

• ns interact in earth
• Produce µ (follows path of n)
• Detect Cherenkov light in ice with phototubes
  buried in the ice
• Detect upward µs
• Ice filters downward cosmic µs

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Simulated nm N ? m- X
Eµ10 TeV
Eµ 6 PeV

• Measure m energy at the detector by counting the
  number of fired PMTs and the total light.

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Other Reactions
ne N ? e- X
nt N ? t- X
nt ? t
PeV t(300 m)
t decays

• Electron Cascade
• 1 PeV 500 m diameter

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IceCubeString
60 optical sensors/string
OM Spacing 17 m
Main Cable
DOM
HV and Base
1400 m
String
Gel
photomultiplier
Glass pressure sphere rated to 10,000 psi Outer
diameter 13
2400 m
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Digital Optical Module - (DOM)

• Self-triggers on each pulse
• Captures waveforms
• Time-stamps each pulse
• Digitizes waveforms
• Performs feature extraction
• Buffers data
• Responds to Surface DAQ
• Set PMT HV, threshold, etc

DOM Board
33 cm
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Requirements for One ElementDigital Optical
Module (DOM)

• 1 to 10,000 photons that are incident over
  several µs
• ? High dynamic range waveform recording

• Time resolution lt 5 ns rms
• Waveform capture
• gt 250 MHz for first 500 ns
• 40 MHz for 5000 ns
• Dynamic Range
• gt 200 PE / 15 ns
• gt 2000 PE / 5000 ns
• Dead-time lt 1
• OM noise rate lt 500 Hz (40K in glass sphere)

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Time-stamping in DOM

• Course time-stamp
• local 40 MHz clock
• Very stable Df/f 6 x10-11/s
• Dt 25 ns not enough by itself
• Okay for triggering
• Fine time-stamp
• pulse sample in ATWD
• Dt 3.3 ns (algorithm can do better)

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Time Synch-ronizing Modules
Surface
DOM
dt
Dtdown Dtup1/2(Tround-trip- dt)
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Network

• Copper-wire 0.9 mm ? in twisted-pair Adequate for
  ICECUBE needs
• Power lt3 Watts/DOM (lt20 loss)
• Timing lt5 ns rms throughout time-base
• Messaging control, code modifications
• Data 5 - 100 kBytes/second/DOM
• InIce Two DOMS/pair, to save , bulk, logistics
• IceTop One DOM/pair, to get bandwidth

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DAQ Network Architecture
String - Electronics in the ice
Global Timing
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AMANDA String 18

• Springboard for transition to IceCube
• 41 DOMs deployed in 99/00 season 37 operational
• Test bed download new code into ice
• Communicate and program in North America

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String 18 DOM Board
Oscillator
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Digital ATWD Waveforms
Hi Gain
Single Photon ADC Spectra
Bucket
Low Gain
Bucket
No Gain
ADC Charge
Bucket
Complex Waveform _at_600 MHz
Clock
Digitalization _at_ 600 Hz
Bucket
Slow ADC
Bucket

• ATWD Channels 1 - 4 1.7 ns/sample for 217 ns
• ADC 60 ns/sample for 7.7 ms

Time
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Timing with Phone Wire to few ns

• Transit time for 2.5 km twisted pair 12 ?s
• Rise-time after propagation 2 ?s (1/t)
• Use a bipolar Time-Mark signal pulse
• Digitize time-mark pulse _at_ 20 MHz, 10-bit
• Fit leading edge baseline 3.5 ns rms

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Timing with µs
T (DOMN)
12 m
Dt - ns
T (DOMN1)

• DT T (DOMN) - T (DOMN1)
• Two clear components
• random coincidences (flat)
• correlated light (peak at 0)

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Reconstructed m Event

• Only first hit in each OM shown
• Down flow of light
• No early photons
• Late hits consistent with
• light scattering, or
• a second m?
• Down going m

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String 18 Performance

• Timing 3.5 ns rms (very stable)
• SPE spectrum as expected
• PMT Gain Drift ltlt0.2 /week
• LED Beacons 8 ns rms (ice optics)
• Down going ? observed
• µ waveforms 15 have gt 1 hit

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Summary

• IceCube New detector under development to
  explore astrophysical ns
• Decentralized timing with digital technology
• Measure full waveform
• Provides more information for reconstruction
• More detail for physics discovery
• Feature extraction - less data to record and
  transmit
• Can synchronize separate and remote elements to
  several ns
• Fully functional prototypes tested with muons in
  AMANDA
• Prototypes meet or exceed IceCube requirements

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IceCube Collaboration

• Institutions 11 US, 9 European, 1
  Japanese and 1 Venezuelan
• Bartol Research Institute, University of Delaware
  ()
• BUGH Wuppertal, Germany ()
• Universite Libre de Bruxelles, Brussels, Belgium
  ()
• CTSPS, Clark-Atlanta University, Atlanta, USA
• DESY-Zeuthen, Zeuthen, Germany ()
• Institute for Advanced Study, Princeton, USA
• Lawrence Berkeley National Laboratory, Berkeley,
  USA ()
• Department of Physics, Southern University and
  A\M College, Baton Rouge, LA, USA
• Dept. of Physics, UC Berkeley, USA ()
• Institute of Physics, University of Mainz, Mainz,
  Germany ()
• University of Mons-Hainaut, Mons, Belgium ()
• Dept. of Physics and Astronomy, University of
  Pennsylvania, Philadelphia, USA ()
• Dept. of Astronomy, Dept. of Physics, SSEC,
  University of Wisconsin, Madison, USA ()
• Physics Department, University of Wisconsin,
  River Falls, USA ()
• Division of High Energy Physics, Uppsala
  University, Uppsala, Sweden ()
• Dept. of Physics, Stockholm University,
  Stockholm, Sweden ()
• Dept. of Physics, University of Alabama, USA

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The End