An Overview of the IceCube Neutrino Telescope Kael Hanson University of Wisconsin – Madison 8th International Conference on Advanced Technology and Particle

An Overview of the IceCube Neutrino

Telescope

Kael HansonUniversity of Wisconsin – Madison

8th International Conference on Advanced Technology and Particle Physics

Villa Olmo, Como, Italy

http://villaolmo.mib.infn.it/c_volta.gif

7/10/2003 K. Hanson - IceCube Overview Slide 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


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.


Ice Properties

K. Woschnagg – UC Berkeley


Detecting Passing Charged Particles In Ice


IceCube Neutrino Flavor Detection

e

Log(energy/eV)12 18156 219

e


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


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


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)


IceCube Sensitivity to Diffuse Fluxes

astro-ph/0305196


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, 104 pe integrated


The Digital Optical Module (DOM) (2)


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: 108 @ 1500 V typ.• IceCube operating range ~ 107

with modified bleeder


PMT Noise vs. Temperature


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

• 1st 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 1st dynode

• High-Z bleeder (70 MΩ)


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: T50 ~ 350 nm or less and residual sensitivity down to 315 nm: -2 Cherenkov .


DO

M M

ain

board

2x ATWD

Analog Front End

ExcaliburPower + Signal

Flasher Board Interface

HV Board Interface

Memories

CPLD



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


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.


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.


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 km2·yr achieved 2007!• Construction of IceCube from 2005 to 2010 when

full detector will be online.



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.


Flasher Board

• 12 UV LEDs mounted at 60º separation around perimeter of board (2 per site)

• Capable of producing 106 to 1010 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.

Documents

An Overview of the IceCube Neutrino Telescope Kael Hanson University of Wisconsin – Madison 8th International Conference on Advanced Technology and Particle