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Optical Sensor and DAQ in IceCube

Optical Sensor and DAQ in IceCube. Albrecht Karle University of Wisconsin-Madison karle@amanda.wisc.edu. Chiba July, 2003. Outline. Events signatures and their requirements on DAQ. The design of the optical sensor for IceCube. A brief construction status. The IceCube Collaboration.

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Optical Sensor and DAQ in IceCube

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  1. Optical Sensor and DAQin IceCube Albrecht Karle University of Wisconsin-Madison karle@amanda.wisc.edu Chiba July, 2003

  2. Outline • Events signatures and their requirements on DAQ. • The design of the optical sensor for IceCube. • A brief construction status.

  3. The IceCube Collaboration Institutions: 11 US, 9 European institutions and 1 Japanese institution; ≈150 people • 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 • Dept. of Technology, Kalmar University, Kalmar, Sweden • 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 • Fysikum, Stockholm University, Stockholm, Sweden • University of Alabama • Vrije Universiteit Brussel, Brussel, Belgium • Dept. of Physics, niversity of Maryland, USA • Chiba University, Japan

  4. IceTop AMANDA South Pole Skiway 1400 m 2400 m IceCube • 80 Strings • 4800 PMT • Instrumented volume: 1 km3 (1 Gt)

  5. AMANDA-II Track reconstruction in low noise environment 10 TeV • 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) 1 km

  6. Point sources: event rates Flux =dN/dE = 10-6*E-2/(cm2 sec GeV) equal to AMANDAB10 limit

  7. Point source sensitivity The sensitivity of IceCube to an E^-2 neutrino spectrum is comparable to the sensitivity of GLAST to an E^-2 photon spectrum (1yr) IceCube 3 years

  8. Cascade event Energy = 375 TeV ne + 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

  9. t + N --> t- + X t + X (82%) Double Bang Learned, Pakvasa, 1995 Regeneration makes Earth quasi transparent for high energie ; (Halzen, Salzberg 1998, …) Also enhanced muon flux due to Secondary µ, and nµ (Beacom et al.., astro/ph 0111482) E << 1PeV: Single cascade (2 cascades coincide) E ≈ 1PeV: Double bang E >> 1 PeV: partially contained (reconstruct incoming tau track and cascade from decay)

  10. 300 m 0 m -300 m 0 m 300 m Density profile of double bang event Shown is the expected photoelectron signal density of a tau event. The first ntinteraction is at z=0, the second one at ≈225m. The diagram spans about 400m x 800m. 105 103 10 Photoelectrons/PMT 10-1

  11. Complex waveforms provide additional information Capture Waveform information E=10 PeV String 5 String 4 String 3 String 1 String 2 Events / 10 nsec 0 - 4 µsec

  12. Observed waveforms in Ice N2-Laser event generated by in situ laser: Amplitude: ≈ 10^10 photons, Wavelength: ≈ 335 nm Pulse width: ≤ 10 nsec- comparable to ≈300 TeV cascade Distance of OM Data Simulation 45 m * 115 m 167 m 2 µsec *HV of this PMT was lowered

  13. Eµ=10 TeV ≈ 90 hits Eµ=6 PeV ≈ 1000 hits Energy reconstruction Small 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.

  14. 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.

  15. A remark on the side for EeV fans Eµ=10 TeV ≈ 90 hits Eµ=6 PeV ≈ 1000 hits The 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>EeV optimized geometry in ice could be. (String spacing ≈ 1 km)

  16. 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 DAQ design: Digital Optical Module- PMT pulses are digitized in the Ice DOM For more information on the Digital Optical Module: see poster by R. Stokstad et al. 33 cm

  17. Assembled DOM

  18. 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. Photomultiplier:HamamatsuR7081-02 (10”, 10-stage, 1E+08 gain)

  19. Custom design: 5000 DOMs, 2500 copper pairs, 800 PCI cards (10 racks) DAQ Network architecture Off the shelf IT infrastructure, Computers, switches, disks DAQ Software Datahandling software

  20. Digital Optical Module (DOM) Main Board Test Card

  21. 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

  22. Design goals Operational parameters (typical) SPE: 5 mV Electronic noise: <0.2 (0.1) V Dynamic range: 200 PE/15 nsec 1000 PE/4 µsec Overall noise rate of DOM: 500 - 1000 Hz

  23. IceCube String 1400 m OM Spacing: 17 m 2400 m

  24. The DOM communicates via ≈3km copper wires to the central DAQ 2 DOMs on one twisted pair Bandwidth goal: 1 Mbit/sec

  25. The DOM Receiver (DOR):a PCI Card

  26. 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.

  27. The DOM Hub (prototype)

  28. Counting room 52’ x 28’ Preliminary, (30%)

  29. Counting House will be very similar to other buildings at the South Pole. ARO building, South Pole

  30. 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.

  31. Example of a dark freezer laboratory. up to 300 DOMs @ -50°C

  32. Production of drill components

  33. The big reel for the hotwater drill

  34. New drill: Faster and more reliable. Drilling time to 2000 m depth: 35 h (AMANDA: 80h) Diameter: 50 cm Hotwater Drilling Picture: AMANDA drill

  35. South Pole Dark sector Skiway AMANDA Dome IceCube

  36. First Deployment planned in 04/05 season. No more freezing: Deployment will be in heated environment.

  37. Construction: 11/2004-01/2009 Grid North 100 m AMANDA South Pole SPASE-2 IceCube Dome Skiway Next season: Buildup of the Drill and IceTop prototypes

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