Mark Krasberg

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Penguin Training
DOM-related material
Madison, Wisconsin
Mark Krasberg, June 4th, 2008
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The IceCube Neutrino Telescope
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SeeingCosmic Messengers

• visible light
• light of other wavelengths
• blue, red, infrared,
• X-rays, radiowaves,.

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in 1054 a star explodes in the constellation Tauru
s
Crab Nebula
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Infrared Picture
X-ray Picture
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neutrinos ?
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SeeingCosmic Messengers

• light
• light of other wavelengths
• blue, red, infrared,
• X-rays, radiowaves
• neutrinos instead of
• photons (particles of light)

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new window on the Universe ?expect surprises
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Getting to the South Pole
A six hour flight from New Zealand to McMurdo
Station, via C-141 Starlifter (now C-17
Globemaster is used)
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A three hour flight from McMurdo to South Pole
Station, via C-130 Hercules
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Leaving Antarctica on a C-17
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Amundsen-Scott South Pole Research Station
C-130 runway
IceCube Lab
Drill camp
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The Design
9 strings and 16 IceTop stations deployed
2005-2006

• 1 Gton instrumented volume
• gt70 strings of 60 Digital Optical
  Modules (DOMs)
• 1450-2450 m deep
• 17 m spacing
• 125 m hexagonal grid
• geometry optimized for
• detection of TeV PeV ns
• DOMs look downward
• No single point failure
• 1 cable/2DOMs
• IceTop air shower array
• 2 surface tanks for each
  string/station (2m
  diameter)
• each tank contains 2 DOMs

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IceCube
IceTop
total of 40 Strings 80 IceTop tank
Air shower detetor threshold 300 TeV
1450m
InIce
80 Strings , 60 Optical Modules 17 m between
Modules 125 m between Strings
AMANDA (1995-2000) 19 Strings 677 Modules
2450m
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DOM Testing
Final Acceptance Test

• Check basic DOM optoelectronic function
• Perform extended life and stability tests of DOMs
  in temperature cycled environment over weeks
• Calibrate DOM optical sensitivity

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DOM Testing

DFL (Dark Freezer Lab) is large, dark, cold
container which holds N test stations (N is
site-dependent) each of which schematically looks
like the figure. Optical fiber system carries
light from optics breadboard (diode laser, LED
pulser, monochromator-tuned lamp) to each
DOM. Optics spreads light evenly out across PMT
photocathode.
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SPTS South Pole Test System a compact
recreation of SPS S-CUBE 64 mainboards Used to
test all DOMHubs prior to shipment to
Pole (Sebastian and Justin)
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• Working time Nov. - mid-Feb
• Plan deploy 14 strings/season
• Completion 2011

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Deployment of 39-01
Frigophobia
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The DOMs
Each DOM is an autonomous data collection
unit Power consumption 3W

• Measure arrival time of every photon
• 2 Analog Transient WD digitizing at 300 MHz
• for 400 ns (signal complexity) and FADC
• recording at 40 MHz FADC 6.6 ms (event
• duration in ice)
• Dynamic range 500pe/15 nsec
• 25000 pe/6.4 ms
• Can do local coincidence triggering
• transmits to surface at request via digital
  communications
• Send all data to surface over 3.3 km twisted pair
  
• copper cable power, data and time stamping

25 cm Hamamatsu PMT
Main board
PMT base
Clock stability 10-10 0.1 nsec /
sec Synchronized to GPS time every 5 sec at a
precision rms 2 nsec (Rapcal calibrations)
LED flasher board 12 LEDs
33 cm Benthosphere
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Single photoelectronpulses recorded with ATWD
10 pulses are superimposed

• Single photoelectron pulses (SPE) recorded in 6
  DOMs during the final acceptance test.
• All PMT gains are set to 1E7.
• Threshold at 0.3 SPE
• FWHM13.6 ns

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DOM Waveform Capture
High Gain

• Altera Excalibur ARM922t mP 400k gate FPGA on a
  single chip
• CPU runs data acquisition, testing facility, and
  diagnostic utilities
• FPGA controls communications interface, time
  critical control of DAQ hardware, fast feature
  extraction of waveforms
• 2 ATWD each with 4 channels capable of
  digitizing 128 samples at rates from 0.25 1.0
  GHz. 2 of them for ping-pong mode.
• 3 gain channels in ATWD for complete coverage of
  PMT linear region
• 10-bit, 40 MHz FADC for capture of extended
  photon showers in the ice (6 ms wide).

Medium Gain
Low Gain
t
? 400 ns window
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Pulse shapestaken in situ

• Pulse shapes are recorded with three ATWD
  channels for high dynamic range coverage.
• Runs of 10 flasherboard pulses at 5 different
  brightness settings are shown.
• High saturation in channel 0 (high gain), but
  good coverage of the brightest pulses in channel
  2 (low gain).

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ATWD and FADC

• Pulse shapes are recorded with ATWD and with
  FADC.
• Shown is an average flasher pulse and a single
  shot superimposed at 125 m distance.
• The ATWD captures 400 ns of this pulse (top).
  The full waveform is recorded in the FADC
  (bottom).

Here the flasher is 21-55 and the receiver is
29-55 (neighboring string, 125m away). This is a
50 nsec pulse, maximum brightness, six
horizontal LEDs flashing.The smooth curve shows
the average of several thousand events.   One
example waveform is superimposed.
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Deployment
98.5 of 2560 DOMs survive deployment and
freeze-in
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String 39 two-week freeze-in movie
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IC22
Only 30 Hz of the rate is actual signal
(remember to talk about Antares)
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IC40 Noise rates(April 8, 2008)


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DOM Hookups

• Cables
• 2 DOMs per twisted pair
• 2 twisted pairs per quad cable
• 15 quad cables per InIce Cable (60 DOMs)
• Local Coincidence
• Each DOM talks to its neighbors on either side
  (UP and DOWN)
• A neighboring hit can be used to cut down rates,
  confirm the signal is real
• Depending on which DOM is the neighbor, the
  electronic LC signal has to travel between 17
  meters and 51 meters

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Problematic DOMs from 2007

• A few DOMs do not power up at all (pretty
  serious!)
• zero from 04/05
• four from 05/06
• one from 06/07 (broken connector may be the
  culprit)
• Several wire pairs exhibit high current
• At least two categories
• Ultra-high current DOMs
• 3 wire pairs (6 DOMs total)
• there may be a solution, based on a DOM
  Arizona, which was detected as being high
  current at the pole and returned to Wisconsin
• Marginal high current DOMs
• 7 DOMs total
• Associated with broken LC
• a DOM called Haifa is under study may yield
  answers
• Clustering of high current DOMs from 06/07 is not
  understood
• 2 DOMs broke down last year, 2 DOMs from this
  season have very poor communications

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Results from 2008 commissioning
Commissioned DOMs incl IceTop 1120/1136
Dead 4 (2 shorted)
High Current (unplugged) 4
Poor communications (unplugged) 4
Latecomers (not frozen-in at station close) 4
DOMs with serious rate issues 2
Broken LC DOMs 5
Broken LC links 2
PLD version 25 DOMs deployed at top (cold!) 1
DOMs from 2006/2007 integrated into IC40 6
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40-51 Juneberry 40-52 Alfa_Romeo_Spider
poor comms
50-58 Universitet bad LC
39-08 Shamal bad LC
59-59 Cosmology poor flash
38-59 Blackberry no HV
29-18 Yurei PMT?
49-17 Biometeorology bad flash
30-23 Peugeot_505 no power
50-36 Ocelot no power
29-59 Auroraphobia 29-60 Nix no power
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string 58 67 66 74 73 65
72 78 48 57 47 46 56
High Current / LC breaks on the 13 new strings
from 2006/2007
High Current DOMs
Does not power up
LC break
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DOMs not part of IC40 (broken and unplugged)
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DOMHubMonitor

• SUMMARY
• --------------------------------------------------
  --------------------------------------
• HUB AM 01 02 03 04 05 06 21 29 30 38 39 40 44
  45 46 47 48 49 50
• COMM 2 32 32 32 8 32 24 60 58 58 60 60 58 54
  60 58 58 60 60 59
• --------------------------------------------------
  --------------------------------------
• HUB 52 53 54 55 56 57 58 59 60 61 62 63 64
  65 66 67 68 69 70 71
• COMM 60 58 59 60 60 60 60 60 60 60 60 60 60 60
  56 60 60 55 60 59
• --------------------------------------------------
  ---------------------------------------
• HUB 72 73 74 75 76 77 78
• COMM 58 60 59 60 60 58 60
• --------------------------------------------------
  ---------------------------------------
• HUBS 47 COMM 2527 (max
  number is 2562)
• NO PROBLEMS FOUND

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ComputerMonitor (Victor)

• Checks disk space on all machines
• Alerts if it gets below XXX
• Alerts if it is prediced to fill within XXX hours
• Has already detected two issues at pole!
• Detector would have gone down over the weekend!

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76 DOMs
589 DOMs
1390 DOMs
2515 DOMs

39-22 Liljeholmen stops communicating properly
30-60 Rowan stops communicating
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76 DOMs
589 DOMs
1390 DOMs
2515 DOMs
66-33 New_York and 66-34 Dou_Mu go high
current
39-61 Hydrogen PMT breaks
54-47 Garbanzo_bean stops communicating
39-22 Liljeholmen stops communicating properly
39-21 Aspudden slows down
30-60 Rowan stops communicating
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76 DOMs
589 DOMs
1390 DOMs
2515 DOMs
39-61 Hydrogen PMT breaks
39-22 Liljeholmen stops communicating properly
30-60 Rowan stops communicating
66-33 New_York and 66-34 Dou_Mu go high
current
54-47 Garbanzo_bean stops communicating
39-21 Aspudden slows down
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Carefully model optics of ice!
Dark and transparent environment for Cherenkov
light detection Polar ice ??abs (blue)
100-200 m leff. scat 25 m
IceCube new strings compared to string 48
dust layer
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muon energy loss in the detector
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The first 40-string event(data taken March 10,
2008)
Flash 46-57 Qi
Flash 46-27 Tulip
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December 13, 2006 solar flare in IceCube
IceTop and Spaceship Earth Observations of the
Solar Flare
Dec 13, 2006 X3-Class Solar Flare (SOHO)
Photograph of auroras from Dec 14, 2006 near
Madison, WI
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How to refer to a DOM

• The official way to refer to a DOM is by location
  and name
• 29-54 Nomatophobia
• The names stick out, problems become easier to
  track and identify
• DOMs have other identifiers
• DOMid TP5P0647
• Electronic mainboard id fe6b36e170cc

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IceCube-9
Photographs of Frigophobia and the IceCube
drill camp taken by Mark Krasberg, 2006
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IceCube http//icecube.wisc.edu
United states

• Univ Alaska, Anchorage
• UC Berkeley
• UC Irvine
• Clark-Atlanta University
• U Delaware / Bartol Research Inst
• University of Kansas
• Lawrence Berkeley National Lab
• University of Maryland
• Pennsylvania State University
• University of Wisconsin-Madison
• University of Wisconsin-RiverFalls
• Southern University, Baton Rouge

Europe
University Utrecht

• Universite Libre de Bruxelles
• Vrije Universiteit Brussel
• Université de Mons-Hainaut
• Universiteit Gent

• Uppsala University
• Stockholm University

• University of Oxford

• Universität Mainz
• Humboldt Univ., Berlin
• DESY, Zeuthen
• Universität Dortmund
• Universität Wuppertal
• MPI Heidelberg
• RWTH Aachen

Chiba University
Japan
New Zealand
Univ. of Canterbury, Christchurch
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Backup Pictures
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