IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 1 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 2 Optical vs. Radio & Acoustic  IceCube has been optimized for energies in the range between roughly 1 TeV and 10 PeV  The buried array relies on one type of detection channel: optical ● Cherenkov light from UHE -induced charged particles  att ~ 30m requires high module density – IceCube has  ~5000/km 3 ● To get sufficient statistics at higher energy scales (e.g., GZK scale), where one needs a fiducial volume closer to km 3, need technology that is practical at lower module densities

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 3 Optical vs. Radio & Acoustic  Happily, ice is also well-suited for detection of UHE neutrino-induced radio and acoustic signals ● Cherenkov radio signals  ~1km attenuation length  proven technology (RICE) ● Acoustic signals  ~10km attenuation length  potentially very quiet environment (vs., e.g., ocean)  Coincident event capture offers many benefits ● Therefore, in this talk we will focus on efforts using ice at the South Pole ● Will not cover other very interesting and promising radio and acoustic efforts, like ANITA, SalSA, SAUND,…

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 4 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 5 Focus on “Guaranteed” UHE Neutrinos  GZK flux models From Gorham et al., Phys. Rev. D72 (2005) ● Roughly speaking, depending on various assumptions, to detect one GZK /yr at eV requires V eff ~ 4-50 km 3  See, e.g., Engel, Seckel and Stanev, Phys. Rev. D64 (2001)

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 6 Discovery Aperture vs. E Saltzberg, astro/ph

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 7 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 8 UHE Neutrino Radio Detection: RICE  Design ● 20-channel array of dipole antennas ● m depths ● 200x200x200 m 3 deployment volume ● Analog readout into surface digitizers 5 m 10 cm

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 9 UHE Neutrino Radio Detection: RICE  Results (Kravchenko et al., astro-ph/ ) ● RICE livetime of ~20500 hrs (V eff ×livetime ~ 1-10 km eV) ● (Results from GLUE, ANITA, FORTE in the literature & at this workshop)

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 10 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 11 New Ideas for Radio at the South Pole  “ROCSTAR” ● Retrofitted OptiCal SysTem Adapted for Radio ● Piggybacks on existing IceCube DOMs  Use Main Board as-is for timing and power  Replace “flasher board” with radio digitizer board to process all radio-related signals – use pre-existing interface bus to MB  Remove PMT, HV stuff, etc.  Rename it “DRM” for Digital Radio Module

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 12 Possible ROCSTAR Node Configuration ≈50m

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 13 Possible ROCSTAR Block Diagram AntennasAntennas Local coincidence triggering

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 14 ROCSTAR Deployment Depth  Optical-Radio coincident event rate can be substantial  Preferable to deploy close to surface, but temperature still reasonably cold (-42C) at 1450 m  Simulations needed to optimize geometry ROCSTAR Nodes (~70)

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 15 ROCSTAR  Advantages ● Uses existing hardware with minimal modification to significantly enlarge radio array at the South Pole ● Straightforward to integrate into existing optical array data acquisition system to make functioning hybrid detector and see coincident events ● Minimal impact on IceCube deployments  Disadvantages ● Geometry somewhat inflexible, not optimal ● Use of existing hardware imposes some constraints on design of in-ice radio electronics (probably not severe)

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 16 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 17 Surface Array  Calibration of UHE neutrino detectors is tricky due to lack of a “test beam” ● IceCube approach  in-situ light sources (LEDs, lasers) to mimic cascade events up to ~50 PeV  cosmic-ray muons and atmospheric  -induced muons up to about 10 TeV ● Radio and Acoustic approaches  in-situ (or nearby) transmitters  New idea (Seckel & Seunarine) ● use Askaryan radio pulse produced when cosmic-ray air shower core’s particles hit the earth (or the ice upon it)  comprise a few % of the energy of the air shower

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 18 Surface Array  Use an array of radio antennas near the surface at the Pole  Trigger with IceTop, the air shower array atop the IceCube buried array  With E p >3PeV, a 30 m × 30 m array would see ~1 ev/hr  Not just for radio array calibration ● cosmic-ray composition studies may be possible too  RICE might be able to do this  More simulation work needed

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 19 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 20 UHE Neutrino-Induced Acoustic Signals  A -induced cascade will produce localized heating in the medium, creating a pressure wave  Detect sound, peaked at ~40kHz, with detectors distributed in the ice at the South Pole  Short-term issues: ● absorption length  probably large; must measure ● refraction ● background noise  probably small; must measure – man-made on surface – slip-stick of glacier on bedrock – micro cracks  N.B.: No noise from dolpins, ships, wind, waves,… S. Boeser/DESY

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 21 UHE Neutrino-Induced Acoustic Signals  Predicted attenuation length for sound in ice looks very promising (plot below is for 10kHz): Depth variation is due to change in temperature of the ice at Pole. J. Vandenbroucke/ARENA 2005

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 22 Acoustic Detection Contours in Ice Contours for P thr = 9 mPa: raw discriminator, no filter J. Vandenbroucke/ARENA 2005 longitudinal coord. lateral coord.

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 23 Acoustic Signals: SPATS South Pole Acoustic Test System  Purpose: measure ● noise ● refraction ● attenuation length  Design for 06/07 season ● Deploy in 3 IceCube holes at 400m depth ● 7 acoustic stages per hole  sensor and transmitter ● 3 surface interface boxes  power, network interface ● 1 master CPU  network interface, GPS timestamp

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 24 SPATS Module Modules at DESY/Zeuthen Sensor ModuleOne Full Module

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 25 After SPATS…  If the measurements made with SPATS during the 2006/2007 season at the South Pole are encouraging, the next step will be to plan and hopefully build a much larger device ● ~100 km 3 effective volume at GZK energies ● ~100 strings on 1 km spacing grid ● ~300 receivers per string (co-deployed with radio)

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 26 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 27 Hybrid “IRA” Detector  As in HEP and Auger, using more than one detection technique to view the same fiducial volume is highly advantageous ● Detecting events in coincidence between 2-3 methods is more convincing than detections with 1 method alone ● Coincident events allow calibration/cross-checks one method relative to the others ● Hybrid reconstruction will give superior energy and direction resolution than with one method, or at least will allow reconstruction of coincident events that cannot be reconstructed with one method alone  Good complementarity ● Overlapping sensitivities in energies around PeV  At lower energies, optical device is better  At higher energies, radio/acoustic are better  The resulting hybrid detector would have sensitivity to neutrinos over about 10 orders of magnitude in energy! Halzen & Hooper “IceCube Plus” JCAP 01 (2004) 002

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 28 Hybrid IceCube+Radio+Acoustic  Simulations* have been made of a hybrid detector consisting of ● IceCube plus 13 “outrigger” strings (×) ● 91 additional radio/acoustic holes with 1 km spacing (o)  5 radio receivers m  300 acoustic receivers, m  2  acceptance, hadronic shower only (LPM stretches EM showers), E sh = 0.2E *See D. Besson et al., ICRC 2005

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 29 Hybrid IRA Simulation  Result: ● V eff at E>10 17 eV increased by a factor of 5-25 over IceCube alone (V eff > ~100km 3 ) ● ~20 GZK events/year  Notes: ● ESS flux, Gandhi  ’s,   = 0.7 ● For R, A, R+A  all flavors  NC and CC ● For O**  only  I=IceCube R=Radio A=Acoustic (GZK ’s/yr) V eff (km 3 ) Log 10 [E /eV]

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 30 Some Comments on UHE  with IRA  High energy tau neutrinos are especially good candidates for coincident event capture; V eff increases by a lot ● Double bangs  one bang in radio/acoustic array, one in optical array ● Lollipops  detect tau lepton track in optical array, tau decay cascade in radio/acoustic array ● Sugardaddies (see talk by T. DeYoung)  detect tau lepton creation in radio/acoustic, tau decay to muon in optical array

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 31 Beyond the South Pole Outline  Introduction: Optical vs. Radio & Acoustic  Moving to the GZK scale: E > eV sensitivities  Radio ● RICE ● Near-term future ideas  ROCSTAR/DRM  Surface array  Acoustic ● Near-term future ideas  SPATS  Capabilities of a combined IceCube, Radio and Acoustic (IRA) detector  Comments on IRA  sensitivities  Conclusions

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 32 Conclusions-I  We believe we can get to effective volumes large enough to detect a large sample of GZK neutrinos at the South Pole using radio and/or acoustic techniques ● If IceCube or ANITA see some events, IRA will see ~100 with several years’ operation—start to do astronomy with them ● Also, start to do particle physics—measure neutrino-nucleon cross section at ~100 TeV CM to 30% (Ref.: Connolly, ARENA 2005)  The cost of drilling (shallower and narrower) holes and of the individual radio and acoustic elements is very reasonable (very roughly, ~$30k/hole for drilling, ~$50k for radio + acoustic sensors)  Operating optical, radio and/or acoustic detectors in coincidence will not only produce more convincing individual events, but also extend the reach and accuracy compared to any one detector alone

IRA April 2006 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE  Workshop 33 Conclusions-II IceCube will be a vast improvement over AMANDA, but some things never change… IceCube