1. An Overview of the IceCube Neutrino Telescope Kael Hanson University of Wisconsin – Madison 8th International Conference on Advanced Technology and Particle Physics Villa Olmo, Como, Italy

2. 7/10/2003K. Hanson - IceCube OverviewSlide 2 IceCube Collaboration Bartol Research Institute, University of Delaware, Newark, DE 19716, USA Fachbereich 8 Physik, BUGH Wuppertal, D-42097 Wuppertal, Germany Université Libre de Bruxelles, Science Faculty CP230, Boulevard du Triomphe, B-1050 Brussels, Belgium CTSPS, Clark-Atlanta University, Atlanta, GA 30314, USA Dept. of Physics, Chiba University, Chiba 263-8522 Japan DESY-Zeuthen, D-15738 Zeuthen, Germany Astrophysics, Imperial College, London SW7 2BW, UK Institute for Advanced Study, Princeton, NJ 08540, USA Dept. of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Dept. of Astronomy and Astrophysics, Penn State University, University Park, PA 16802, USA Dept. of Physics, Southern University, Baton Rouge, LA 70813, USA Dept. of Physics, University of California, Berkeley, CA 94720, USA Institute of Physics, University of Mainz, Staudinger Weg 7, D-55099 Mainz, Germany Dept. of Physics, Oxford University, Oxford OX1 3PU, UK Dept. of Physics, University of Maryland, College Park, MD 20742, USA Dept. of Physics, George Mason University, Fairfax, VA 22030 USA University of Mons-Hainaut, 7000 Mons, Belgium Departamento de Física, Universidad Simón Bolívar, Caracas, 1080, Venezuela Dept. of Astronomy, University of Wisconsin, Madison, WI 53706, USA Dept. of Physics, University of Wisconsin, Madison, WI 53706, USA SSEC, University of Wisconsin, Madison, WI 53706, USA Physics Dept., University of Wisconsin, River Falls, WI 54022, USA Division of High Energy Physics, Uppsala University, S- 75121 Uppsala, Sweden Faculty of Physics and Astronomy, Utrecht University, NL- 3584 CC Utrecht, The Netherlands Dept. of Physics, Stockholm University, SE-10691 Stockholm, Sweden Vrije Universiteit Brussel, Dienst ELEM, B-1050 Brussels, Belgium Department of Physics & Astronomy, University of Canterury, Christchurch 8020, New Zealand

3. 7/10/2003K. Hanson - IceCube OverviewSlide 3 The South Pole Site the InIce array: 80 strings of 4800 DOMs arranged in hexagonal lattice 1400 m – 2400 m beneath surface IceCube is two tightly coupled sub-detectors which share triggers and contribute data to common event structures: the IceTop array: a surface array of frozen water tanks for monitoring airshowers, to provide a veto for InIce array, and calibration of InIce array. 2 tanks per station at top of each string. 2 DOMs per tank.

4. 7/10/2003K. Hanson - IceCube OverviewSlide 4 Ice Properties K. Woschnagg – UC Berkeley

5. 7/10/2003K. Hanson - IceCube OverviewSlide 5 Detecting Passing Charged Particles In Ice

6. 7/10/2003K. Hanson - IceCube OverviewSlide 6 IceCube Neutrino Flavor Detection

7. 7/10/2003K. Hanson - IceCube OverviewSlide 7 Recent AMANDA Results AMANDA –II Preliminary AMANDA-II Point Source Search (astro-ph/0309585) Sky map of 699 neutrino candidate events. No evidence for excess. Diffuse sources search with AMANDA-II detector NEW

8. 7/10/2003K. Hanson - IceCube OverviewSlide 8 AMANDA Publications Supernovae: Astropart.Phys.16:345-359, 2002 Point Sources: Astrophys.J.583:1040-1057, 2003 Diffuse Cascades: Phys.Rev.D67:012003, 2003 Atmospheric Neutrinos: Phys.Rev.D66:012005, 2002 WIMPS: Phys.Rev.D66:032006, 2002

9. 7/10/2003K. Hanson - IceCube OverviewSlide 9 Detector Performance (astro-ph/0305196) Cascades: Localized to detector volume Very good vertex and energy resolution Muons: Travel great distances through ice Sub-degree pointing resolution (ptsrc)

10. 7/10/2003K. Hanson - IceCube OverviewSlide 10 IceCube Sensitivity to Diffuse Fluxes astro-ph/0305196

11. 7/10/2003K. Hanson - IceCube OverviewSlide 11 The Digital Optical Module (DOM) DOM asynchronously records hits – buffers until surface readout requests data (8 MB acquisition memory) Hits time stamped with local oscillator. This must be trans-formed at surface to UT /w/ overall time res. of < 5 ns! DOM-to-surface communication bandwidth approximately 1 Mbit IceCube detector contains 4800 InIce and 360 IceTop modules. Each DOM is autonomous DAQ platform In situ digitization of PMT pulses for increased S/N and better dynamic range: 200 pe instantaneous, 10 4 pe integrated

12. 7/10/2003K. Hanson - IceCube OverviewSlide 12 The Digital Optical Module (DOM) (2)

13. 7/10/2003K. Hanson - IceCube OverviewSlide 13 Photomultiplier Tube Hamamatsu R7081-02 Large area (10” dia.) bi-alkali photocathode deposited on borosilicate glass envelope. 10 dynode stages in box-and-line configuration Fast pulse (6.5 ns width; < 3 ns risetime; < 3 ns FWHM TTS) Very low noise (250 cps typ. @ -40 ºC and ¼ pe counting threshold)! High gain: 10 8 @ 1500 V typ. IceCube operating range ~ 10 7 with modified bleeder

14. 7/10/2003K. Hanson - IceCube OverviewSlide 14 PMT Noise vs. Temperature

15. 7/10/2003K. Hanson - IceCube OverviewSlide 15 High Voltage Base HV Base 0-2048 V 12-bit DAC 12-bit ADC readback Two solutions with differing HV unit but identical digital interfaces: “Active” “Passive” Active Base 2× Cockroft-Walton 1 st dynode fixed – 600 V Anode voltage digitally controllable Technology used in some AMANDA-II OMs + ANTARES Passive Base Modular HV design: HV generator Digital interface board “Classical” resistor- divider HV bleeder Proportional 1 st dynode High-Z bleeder (70 MΩ)

16. 7/10/2003K. Hanson - IceCube OverviewSlide 16 Pressure Sphere Vendor – many decades of experience with deep sea applications + AMANDA OMs 13” O.D., 0.5” thick borosilicate glass hemispheres joined under negative pressure Single 5/8” penetrator brings in power, signals. Low noise (require < 300 Hz induced spe rate in PMT) UV transparency: T 50 ~ 350 nm or less and residual sensitivity down to 315 nm: -2 Cherenkov .

17. 7/10/2003K. Hanson - IceCube OverviewSlide 17 DOM Mainboard 2x ATWD Analog Front End Excalibur Power + Signal Flasher Board Interface HV Board Interface Memories CPLD

18. 7/10/2003K. Hanson - IceCube OverviewSlide 18

19. 7/10/2003K. Hanson - IceCube OverviewSlide 19 DOM Waveform Capture and DSP t Altera Excalibur ARM922t  P+ 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. High Gain Medium Gain Low Gain

20. 7/10/2003K. Hanson - IceCube OverviewSlide 20 DOM Surface Readout: DOR and DOM Hub DOM signals readout on surface by “DOMHub” computer DOR card (DORC?) – 32-bit PCI card – is the last piece custom h/w in the IceCube DAQ system. 8 DOM per DOR, 8 DOR per DOMHub → 1 DOMHub per InIce string. IceTop application uses only 4 DOM per DOR → 10 IceTop DOMHubs Industrial rackmount SBC computer (dual 1 GHz PIII) + passive backplane Applications in DOMHub direct readout, buffer data, and re-transmit data packets over IP to downstream DAQ elements.

21. 7/10/2003K. Hanson - IceCube OverviewSlide 21 IceCube DAQ in 2 Minutes! All hits from InIce string readout and presented to String Processor String Processor converts DOM timestamps to UT; searches for temporal- spatial coincidences; passes “trigger primitives” to trigger processor. All single hits buffered until EB releases! InIce / IceTop Trigger Processors may apply additional trigger criteria Global Trigger receives trigger info from IceTop and InIce; may apply additional trigger criteria Event Builder receives trigger chains; queries String Processors (IceTop Data Handlers) for hits; builds events; passes events to online filter system.

22. 7/10/2003K. Hanson - IceCube OverviewSlide 22 Status and Summary We are building the IceCube neutrino telescope: –Hot water drill system nearing completion; to be shipped to South Pole this year. –Production of DOMs has begun 24 ‘engineering’ DOMs built in US 60 pre-production DOM will build Jan ’04 (US, Germany, Sweden) 400 deployment DOM will build Apr ’04 (US, Germany, Sweden) –IceTop prototype tank /w/ DOMs deployed this year We are on-track for deployment of up to six strings in ’04-’05 season 1 km 2 ·yr achieved 2007! Construction of IceCube from 2005 to 2010 when full detector will be online.

23. 7/10/2003K. Hanson - IceCube OverviewSlide 23

24. 7/10/2003K. Hanson - IceCube OverviewSlide 24 Magnetic Shield & Gel Magnetic Shield Made from high-mu metal (Russian origin) Reduces terrestrial magnetic on interior of cage by approx. 50% Increases collection efficiency of PMT Gel Provides index matching of PMT/glass Also the mechanical stabilizer and shock absorber of PMT + board stack assembly GE RTV6156 A+B (degassed, mixed, degassed again) Remains rubbery at very low temp.

25. 7/10/2003K. Hanson - IceCube OverviewSlide 25 Flasher Board 12 UV LEDs mounted at 60º separation around perimeter of board (2 per site) Capable of producing 10 6 to 10 10 photons per pulse. LED current fed back into ATWD channel for precision timing and light emission profiling. Used for studies of ice optics, calibration of OM relative geometry, energy reconstruction studies Not used for calibration of local OM – small LED on DOM mainboard exists for that purpose.