IceCube: A km-scale Detector David Nygren, LBNL ISVHECRI 6-12 September 2004

copyright ©West Nottinghamshire College 2003 The location – at the bottom of the world Distance from Paris km

Fuel ship delivers ~7 million Gallons of fuel Fuel flown to South Pole: To run electrical power plants, Vehicles, and airplanes LC-130: Cargo from McMurdo to The Pole. 3 ½ hr for ~ 800 miles LC-130 Hercules Getting There…

The South Pole Agency: NSF Access: ~ 3 summer months Altitude: ~ 3000 m (Ice thickness) Temperature: - 30º C (summer) Wind: Significant Major Activity: Station Modernization Population: Limited  Intense working conditions

astronomy: km-scale detectors  ultrahigh energy ’s associated with the sources of high energy cosmic rays  top-down scenarios: decays of massive cosmological relics  bottom-up scenarios: ”cosmic accelerators” accreting black holes (eg AGN) colliding neutron stars/black holes  fireball (eg GRB)  cosmogenic ’s  supernova ’s  dark matter  WIMP, Kaluza-Klein  exotica  monopoles, Q-balls, mini black holes

IceCube – a ”next generation” observatory  kilometer-scale successor to AMANDA  Detection of Cherenkov light from the charged particles produced when a  interacts with rock or ice  Direction reconstructed from the time sequence of signals  Energy measurement – counting the number deposited p.e. waveform read out Expected performance wrt AMANDA: increased effective area/volume superior angular resolution superior energy resolution uniform angular response

Measurements: ►in-situ light sources ►atmospheric muons Detector medium: ice optical properties Average optical ice parameters : abs ~ nm sca ~ nm (eff ) Scattering Absorption bubbles dust ice

3 YEAR AMANDA POINT SOURCE SEARCH 922 events [+ declination] Livetime: L Search in 259 rectangular sky bins - bin size is zenith dependent Search for event excess in Northern sky: No clustering observed → No evidence for point sources above horizon: mostly fake events (RA) All events = 1883 PRELIMINARY 961 below the horizon below horizon: mostly atmospheric ν

IceCube concept Deep ice array  80 strings / 60 OM’s each  17 m OM spacing  125 m between strings  hexagonal pattern over 1 km 2  geometry optimized for detection of TeV – PeV (EeV) ‘s  based on measured absorption & scattering properties of Antarctic ice for UV – blue Cherenkov light Surface array IceTop  2 frozen-water tanks (2 OM’s each) on top of every string

IceTop + IceCube: 1/3 km 2 sr for coincident tracks VETO against  All downward events E > 300 TeV with trajectories inside IceTop  Larger events falling outside CALIBRATION  of angular response with tagged  Expect ~100 tagged air showers/day with multi-TeV  ’s in IceCube Muon survey of IceCube

Coincident event

Showers triggering 4 stations give ~300 TeV threshold for EAS array

IceTop Detector 2 m 0.9 m Diffusely reflecting liner

IceTop station Two Ice Tanks 2.7 m 2 x 0.9 m deep (scaled- down version of Haverah, Auger) Integrated with IceCube: same hardware, software Coincidence between tanks = potential air shower Local coincidence with no hit at neighboring station tags muon in deep detector Signal in single tank = potential muon Significant area for horizontal muons Low Gain/High Gain operation to achieve high instantaneous dynamic range: >10 4

IceTop Stations with DOMs – January 2004 Digitized muon signals from DOMs Amplitude (ATWD counts) vs time (ns) power cable signal, freeze control, temperature control cables

Feb 10/11, 2004 Tank 9 with  telescope Tank 10

Primary composition High altitude allows good energy resolution Good mass separation from N  /N e PeV to EeV energy range

DAQ Task Overview Capture information content of highly variable PMT waveforms Capture information content of highly variable PMT waveforms Robust operational behavior Robust operational behavior Very long service life Very long service life Minimal personnel requirements Minimal personnel requirements Coherent a priori software design Coherent a priori software design Minimum power dissipation Minimum power dissipation Acceptable cost Acceptable cost

Special DAQ Requirements High EMI Rejection: High EMI Rejection: Unimpaired by radars, drills, etc. Unimpaired by radars, drills, etc. Justification: 100% availability Justification: 100% availability  No low-level analog signals from OMs Minimum personnel at pole: Minimum personnel at pole:  Automated functionality necessary Remote commissioning, setup Remote commissioning, setup Automated calibration procedures Automated calibration procedures

IceCube: Technology Transition Decision Digital Optical Module (DOM) Digital Optical Module (DOM) All-digital copper network: twisted pairs All-digital copper network: twisted pairs Supplies power to DOM Supplies power to DOM Transmits commands to DOM Transmits commands to DOM Transmits timing signal to DOM Transmits timing signal to DOM Receives data from DOM Receives data from DOM No low-level signals outside of DOM, Fully differential signaling in network

Digital Optical module (DOM)  a semi-autonomous DAQ platform: records timestamps digitizes stores data transmits to surface at request  an optical sensor 10 inch Hamamatsu R-7081 mu metal cage PMT penetrator HV board flasher board DOM main board pressure sphere optical gel delay board Dark noise rate < 1 kHz  SN monitoring within our Galaxy

DOM Mainboard  fast ADC recording at 40 MHz over 6.4  s event duration in ice 2xATWD FPGA Memories HV Board Interface CPLD  FPGA (Excalibur/Altera) reads out the ATWD handles communications time stamps waveforms system time stamp resolution 7 ns wrt master clock  FPGA (Excalibur/Altera) reads out the ATWD handles communications time stamps waveforms system time stamp resolution 7 ns wrt master clock oscillator (Corning Frequency Ctl) running at 20 MHz maintains  f/f < 2x  2 four-channel ATWDs Analog Transient Waveform Digitizers low-power ASICs recording at 300 MHz over first 0.5  s signal complexity at the start of event  2 four-channel ATWDs Analog Transient Waveform Digitizers low-power ASICs recording at 300 MHz over first 0.5  s signal complexity at the start of event  Dead time < 1% Dynamic range > 200 p.e./15 ns > 4000 p.e./6.4  s energy measurement (TeV – PeV)

Time Calibration Process DOM Local Clock: DOM Local Clock: 20 MHz 20 MHz maintains  f/f <1 x /second maintains  f/f <1 x /second Calibration interval: ~10 seconds Calibration interval: ~10 seconds Timing calibration: Timing calibration: Step-pulse by DOM ~1 Hz Step-pulse by DOM ~1 Hz Received pulse: ~ 2  s rise-time Received pulse: ~ 2  s rise-time Single-shot calibration now ~ 3 ns Single-shot calibration now ~ 3 ns “Reciprocal Active Pulsing”: “Reciprocal Active Pulsing”: Cable length offsets to <1 ns Cable length offsets to <1 ns

-time stamped w.f. recorded & analyzed - downgoing muons detected - photon timing accuracy in ice < 8 ns - local clock calibration < 5 ns r.m.s. - 15% of waveforms have > 1 p.e. IceCube design works String 18

IceCube physics performance simulations benefit from AMANDA experience IceCube will be able to identify   tracks from   for E > eV  cascades from e for E > eV   for E > eV Background mainly downgoing cosmic ray  ’s (+ time coinc.  ’s from uncorrelated air showers)  exp. rate at trigger level ~1.7 kHz  atm.  rate at trigger level ~300/day Rejected  using direction/energy/flavor id  temporal/spatial coincidence w. source for E  < 1PeV focus on the Northern sky for E > 1PeV sensitive aperture increases w. energy  full sky observations possible E µ =10 TeV

IceCube effective area and angular resolution for muons Galactic center  E -2  spectrum  quality cuts and bkgr suppression (atm  reduction by ~10 6) further improvement expected using waveform info further improvement expected using waveform info Median angular reconstruction uncertainty ~ 0.8 

Diffuse  flux / Point sources Objective (after removal of atm  background):  reject the steep energy spectrum of atm  retain as much signal as possible from a (generic) E -2 spectrum Use optimized energy cutE   number of hit OM’s E µ =6 PeV, 1000 hitsE µ =10 TeV, 90 hits Diffuse  hard E  cut E  > 100 TeV Point sources  softer E  cut + spatial correlation

Assume generic flux dN/dE = 10 –7 E -2 (cm -2 s -1 sr -1 GeV) Expect ~10 3 events/year after atm  rejection ~75 events/year after energy cut cf background 8 atm atm v signal Sensitivity (1 y): 8.1  E -2 (cm -2 s -1 sr -1 GeV) blue: after atm  rejection red: after E  cut Diffuse  flux

Steady point sources Search cone 1  opening half-angle + ”soft” energy cut (< 1 TeV) Transient point sources – eg GRB Essentially background-free search energy, spatial and temporal correlation with independent observation For ~1000 GRB’s observed/year expect (looking in Northern sky only)  signal: 12  background (atm ): 0.1 Sensitivity GRB (1 y): ~0.2  WB Excellent prospects for detection of GRB ’s within 1-2 years -> if models realistic Sensitivity point sources (1 y): 5.5  E -2 (cm -2 s -1 GeV)

Cascades e  e L cascade ~10 m small cf sensor spacing  ” spherical” energy deposition  at 1 PeV, Ø cascade ~ 500 m  ~10% in log(E/TeV) E = 375 TeV   “double bang” ~300m for PeV  E << 1 PeV 2 cascades coincide E  1 PeV ”double bang” E >> 1 PeV ”lollipop” (partial containment, reconstruct  track + 1 cascade)  sensitivity to all flavors  4  coverage For diffuse flux expect similar sensitivity in the cascade channel as in the muon channel  Considerable improvement of overall sensitivity

Neutralino dark matter astro-ph/ (Lundberg/Edsjö) WIMP orbits in the solar system perturbed Rates from the Earth affected  Rates from the Sun less affected Direct and indirect searches complementary  Past/present history of solar syst.  Low/high energy tail of  vel. distr.  Disfavored by direct search Sun Earth

AMANDA system IceCube AMANDA IceCube Power consum. 2 MW 5MW Time to 2400 m h h Fuel (gal/hole) Set-up time 5 – 6 weeks d AMANDA IceCube Power consum. 2 MW 5MW Time to 2400 m h h Fuel (gal/hole) Set-up time 5 – 6 weeks d Goals  18 holes/season  2450 m deep  straight within 1m  quality logged Goals  18 holes/season  2450 m deep  straight within 1m  quality logged Enhanced Hot Water Drill

Hose-reel at South Pole (Jan 2004) Hose-reel with hose, built at Physical Sciences Laboratory UW-Madison (Nov 2003)

Mounting, testing + drop of string with 60 OMs expected to take ~ 20 hours Mounting, testing + drop of string with 60 OMs expected to take ~ 20 hours

Status of IceCube project  many reviews – international and within the U.S. - strongly emphasize the exciting science which can be performed with IceCube  in Jan 2004, the U.S. Congress approved the NSF budget, including the full IceCube MRE: ~$240M  significant funding approved also in Belgium, Germany and Sweden  in Feb 2004, NSF conducted a baseline review  “go ahead” IceCube strings IceTop tanks 48Jan Jan Jan Jan Jan Jan 2010

AMANDA / IceCube integration Amanda now runs with TWR  data similar in structure to IceCube  work on a s/w trigger Position of 1 st IceCube strings  as close to Amanda as possible  for verification & cross-calibration  … but logistics and safety requirements 1.1 st IceCube strings: Amanda as calibration device 2.IceCube ~ 20 strings + Amanda: powerful combined detector 3.Full IceCube: Amanda included as a fully integrated, low threshold subdetector CONTINUOUS SCIENCE OUTPUT DURING CONSTRUCTION

 drill development on schedule for operation at Pole in Jan 2005  instrumentation  production for the 4 string first season starts this summer  50% PMTs delivered – on schedule  3 DOM production sites  Wisconsin st season  DESY 60 1 st season  Sweden 50 1 st season  spheres ordered – 40 K depleted Benthos (dark noise ~0.8 kHz)  DOM mainboard – LBNLtests great!  DAQ S/W developed  data transfer DOM  DOM Hub  Data Collection prog tested  implementation for first season’s DAQ  cables – Ericsson, Sweden / JDR, Netherlands  preparing for analysis of early data (calibration, testing)  4 DOM’s are collecting IceTop data using test s/w Status of IceCube construction

1st challenge – successful deployment of strings 2004/2005 Summary IceCube is for real ! - and moving ahead at full speed AMANDA experience provides for huge benefits - for deployment, simulations/reconstruction,…. IceCube is expected to be  considerably more sensitive than AMANDA  provide new opportunities for discovery  with IceTop – a unique tool for cosmic ray physics  first data for Neutrino 2006  data taking during construction  first data augment AMANDA data  later AMANDA an integral part of IceCube

USA (12) Europe (11) Venezuela Japan New Zealand Bartol Research Institute, Delaware, USA Univ. of Alabama, USA Pennsylvania State University, USA UC Berkeley, USA Clark-Atlanta University, USA Univ. of Maryland, USA Bartol Research Institute, Delaware, USA Univ. of Alabama, USA Pennsylvania State University, USA UC Berkeley, USA Clark-Atlanta University, USA Univ. of Maryland, USA IAS, Princeton, USA University of Wisconsin-Madison, USA University of Wisconsin-River Falls, USA LBNL, Berkeley, USA University of Kansas, USA Southern University and A&M College, Baton Rouge, USA IAS, Princeton, USA University of Wisconsin-Madison, USA University of Wisconsin-River Falls, USA LBNL, Berkeley, USA University of Kansas, USA Southern University and A&M College, Baton Rouge, USA Universite Libre de Bruxelles, Belgium Vrije Universiteit Brussel, Belgium Université de Mons-Hainaut, Belgium Universität Mainz, Germany DESY-Zeuthen, Germany Universite Libre de Bruxelles, Belgium Vrije Universiteit Brussel, Belgium Université de Mons-Hainaut, Belgium Universität Mainz, Germany DESY-Zeuthen, Germany Universität Wuppertal, Germany Uppsala university, Sweden Stockholm university, Sweden Imperial College, London, UK University of Oxford, UK NIKHEF, Utrecht, Netherlands Universität Wuppertal, Germany Uppsala university, Sweden Stockholm university, Sweden Imperial College, London, UK University of Oxford, UK NIKHEF, Utrecht, Netherlands Chiba university, Japan University of Canterbury, Christchurch, NZ Chiba university, Japan University of Canterbury, Christchurch, NZ ANTARCTICA Universidad Simon Bolivar, Caracas, Venezuela

in ~50 years, the in ~50 years, the physical scale & energy scale have increased by 10 9