Optical Sensor and DAQin IceCube
Albrecht KarleUniversity of Wisconsin-Madison
ChibaJuly, 2003
Outline
• Events signatures and their requirements on DAQ.
• The design of the optical sensor for IceCube.
• A brief construction status.
The IceCube Collaboration
Institutions: 11 US, 9 European institutions and 1 Japanese institution; ≈150 people 1. Bartol Research Institute, University of Delaware2. BUGH Wuppertal, Germany3. Universite Libre de Bruxelles, Brussels, Belgium4. CTSPS, Clark-Atlanta University, Atlanta USA5. DESY-Zeuthen, Zeuthen, Germany6. Institute for Advanced Study, Princeton, USA7. Dept. of Technology, Kalmar University, Kalmar, Sweden8. Lawrence Berkeley National Laboratory, Berkeley, USA9. Department of Physics, Southern University and A\&M College, Baton Rouge, LA, USA10. Dept. of Physics, UC Berkeley, USA 11. Institute of Physics, University of Mainz, Mainz, Germany12. University of Mons-Hainaut, Mons, Belgium13. Dept. of Physics and Astronomy, University of Pennsylvania, Philadelphia, USA14. Dept. of Astronomy, Dept. of Physics, SSEC, University of Wisconsin, Madison, USA15. Physics Department, University of Wisconsin, River Falls, USA16. Division of High Energy Physics, Uppsala University, Uppsala, Sweden17. Fysikum, Stockholm University, Stockholm, Sweden18. University of Alabama19. Vrije Universiteit Brussel, Brussel, Belgium20. Dept. of Physics, niversity of Maryland, USA21. Chiba University, Japan
IceCube
1400 m
2400 m
AMANDA
South Pole
IceTop
Skiway
• 80 Strings• 4800 PMT • Instrumented
volume: 1 km3 (1 Gt)
Track reconstruction in low noise environment
• Typical event: 30 - 100 PMT
fired• Track length: 0.5 - 1.5 km• Flight time: ≈4 µsecs • Accidental noise pulses:
10 p.e. / 5000 PMT/4µsec• Angular resolution: 0.7 degrees• Effective muon detector area: 1 km
(after background suppression)
AMANDA-II
1 km
10 TeV
Point sources: event rates
AtmosphericNeutrinos
AGN* (E-2) Sensitivity(E-2/(cm2 sec GeV))
All sky/year(after quality cuts)
100,000 -
Search bin/year 20 2300 -
1 year: Nch > 32 0.91 610 5.3 x 10-9
3 year: Nch > 43 (7 TeV)
0.82 1370 2.3 x 10-9
Flux =dN/dE = 10-6*E-2/(cm2 sec GeV)equal to AMANDAB10 limit
Point source sensitivity
10-10
10-8
10-6
10-4
102 103 104 105 106
E2
(dN/dE ) [GeVcm
-2s
-1]
Eν( )GeV
- (3 )AMANDA II yr
- 10 ( 97)AMANDA B '
IceCube3 273C
Crab
AGN Core
501 (Mk ν=γ)
. Atm ν
IceCube 3 years
(1yr)
The sensitivity of IceCube to an E^-2 neutrino spectrum
is comparable to the sensitivityof GLAST to an E^-2 photon
spectrum
Cascade event
Energy = 375 TeV
νe + N --> e- + X
•The length of the actual cascade, ≈ 10 m, is small compared to the spacing of sensors•==> ≈ roughly spherical density distribution of light
1 PeV ≈ 0.5 km diameter
ν Double Bang
ν + N --> - + X
ν + X (82%)
E << 1PeV: Single cascade (2 cascades coincide)E ≈ 1PeV: Double bangE >> 1 PeV: partially contained (reconstruct incoming tau track and cascade from decay)
Regeneration makes Earth quasi transparent for high energie ν;(Halzen, Salzberg 1998, …)Also enhanced muon flux due to Secondary µ, and νµ
(Beacom et al.., astro/ph 0111482)
Learned, Pakvasa, 1995
Density profile of double bang event
-300 m 300 m0 m
300 m
0 m
Shown is the expected photoelectron signal density of a tau event.The first ν interaction is at z=0, the second one at ≈225m.The diagram spans about 400m x 800m.
Pho
toel
ectr
ons/
PM
T
10
105
103
10-1
Capture Waveform information
• Complex waveforms provide additional information
E=10 PeV
0 - 4 µsec
Events / 10 nsec
String 1 String 2 String 3 String 4 String 5
Observed waveforms in IceN2-Laser event generated by in situ laser:Amplitude: ≈ 10^10 photons, Wavelength: ≈ 335 nmPulse width: ≤ 10 nsec
- comparable to ≈300 TeV cascade
2 µsec
SimulationData45 m
115 m
167 m
Distance of OM
*
*HV of this PMT was lowered
Eµ=10 TeV ≈ 90 hits Eµ=6 PeV ≈ 1000 hits
Energy reconstructionSmall detectors: Muon energy is difficult to measure because of fluctuations in dE/dx IceCube: Integration over large sampling+ scattering of light reduces the fluctutions energy loss.
Design goals
• IceCube was designed to detect to neutrinos over a wider range of energies and all flavors.
• If one would wish to build a detector to detect primarily PeV or EeV neutrinos, one would obviously end up with a different detector.
Neutrino flavorνμννe ( / )Log ENERGY eV1218156219νe
Eµ=10 TeV ≈ 90 hits Eµ=6 PeV ≈ 1000 hits
A remark on the side for EeV fansThe typical light cylinder generated by a muon of 1E11 eV is 20 m, 1EeV 400 m, 1E18 eV it is about 600 to 700 m. This scaling gives a hint of how one could design a E>EeVoptimized geometry in ice could be. (String spacing ≈ 1 km)
DAQ design: Digital Optical Module- PMT pulses are digitized in the Ice
Photomultiplier
Design parameters:• Time resolution:≤ 5 nsec
(system level)• Dynamic range: 200
photoelectrons/15 nsec• (Integrated dynamic range: >
2000 photoelectrons)• Digitization depth: 4 µsec.• Noise rate in situ: ≤500 Hz
33 cm
DOM
For more informationon the Digital Optical Module:see poster by R. Stokstad et al.
Assembled DOM
Photomultiplier: Hamamatsu R7081-02
(10”, 10-stage, 1E+08 gain)
• Selection criteria (@ -40 °C)• Noise < 300 Hz (SN,
bandwidth)• Gain > 5E7 at 2kV (nom.
1E7 + margin)• P/V > 2.0 (Charge res.; in-situ gain calibration)
• Notes:• Only Hamamatsu PMT
meets excellent low noise rates!
• Tested three flavors of R7081.
DAQ Network
architecture
McParland et. al. -- A Preliminary Proposal for the IceCube DAQ System Architecture -- DRAFT7
DOMPair20 kB/sec
StringProcessor
N x 20 kB/sec
.
All Hits -0.6 MB/sec
80 Strings
String Subsystem:60 DOMs
N pairs
Event LAN100 BaseTTotal traffic: 1.6 MB/secStringCoincidenceMessagesGlobalTriggerEvent Triggers /Lookback Requests forall Strings - 0.8 MB/sec
EventBuilderBuilt events ~ 1 MB/sec(all event builders)
SAN(NetworkDisk Storage)
"DOMHUB"
Lookback RequestsString CoincidenceMessages - 170 kB/secFulfill Lookback Messages 0.6 MB/sec FulfillLookbackMessages
Online LAN100 BaseTTotal traffic: 1MB/sec
Proposed IceCube DAQ Network Architecture
String LAN100 BaseTTotal traffic: 0.6 MB/sec
OfflineDataHandlingTapeSatellite
Custom design: 5000 DOMs,
2500 copper pairs, 800 PCI cards
(10 racks)
Off the shelf IT infrastructure, Computers, switches, disks
DAQ SoftwareDatahandling software
Digital Optical Module (DOM) Main Board Test Card
Waveform Capture:
• Dynamic range /sampling rate (first 400 ns): ~ 14 bits @ ~300 MHz “Analog Transient Waveform Digitizer”
• Dynamic range/sampling rate (~ 4000 ns): ~ 10 bits @ 40 MHz FADC is appropriate solution
• PMT noise rate: ~ 500 Hz Data compression/feature extraction needed
Operational parameters (typical)
SPE: 5 mVElectronic noise: <0.2 (0.1) V
Dynamic range: 200 PE/15 nsec1000 PE/4 µsec
Overall noise rate of DOM: 500 - 1000 Hz
Design goals
IceCube String
1400 m
2400 m
60 optical sensors
Main Cable
SensorBase with HV generatorElectrical
feedthrough forpower + data
Glass pressure sphere. Rated to 10000 psi.Outer diameter: 13"
Photomultiplier
Gel
String
OM Spacing: 17 m
The DOM communicates via ≈3km copper wires to the central DAQ
1350 m
2400 m
IceTop
IceCube
Counting
House
Connector
Surface cable:
from Counting Hose
string position.
Includes IceTop OM.
Length specific for each string.
String :
Fixed Length*: 2420 m
*Actual length may change somehwat.
Need to determine the stretch factor.
2 DOMs on one twisted pairBandwidth goal: 1 Mbit/sec
The DOM Receiver (DOR):a PCI Card
Data transmission
• New test cable from Ericsson tested successfully at 1 Mbit/sec.
• Recent e-mail from K.-H. Sulanke (DESY/LBNL) with attached file labeled: “TX0_RX1_no_problem.PDF”
• Figure shows bit sequence before and after transmission over 3.5 km twisted pair.
The DOM Hub (prototype)
Counting room
Preliminary, (30%)
52’ x 28’
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
Counting House will be very similar to other buildings at the South Pole.
ARO building, South Pole
Low temperature Laboratoriesand Test facilities
• The Collaboration is building production and test facilities in Europe, US and in Japan.
• Sensors to be tested in large dark freezers. • Production, Verification and initial calibration of
each DOM during extended test periods (months) prior to deployment.
Example of a dark freezer laboratory.
up to 300 DOMs@ -50°C
Production of drill components
The big reel for the hotwater drill
Hotwater Drilling
QuickTime™ and aPhoto - JPEG decompressor
are needed to see this picture.
• New drill: Faster and more reliable.
• Drilling time to 2000 m depth: 35 h
• (AMANDA: 80h)• Diameter: 50 cm
Picture: AMANDA drill
South Pole
Dark sector
AMANDA
IceCube
Dome
Skiway
QuickTime™ and aPhoto - JPEG decompressor
are needed to see this picture.
First Deploymentplanned in
04/05 season.
No more freezing:Deployment will
be in heated environment.
Construction: 11/2004-01/2009
FY04:6FY05:12FY06:16FY07:16FY08:16FY09:14
AMANDA
SPASE-2 South Pole
Dome
Skiway
100 m
Grid North
IceCube
Next season: Buildup of the Drill and IceTop prototypes
Top Related