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Beyond IceCube @ the South Pole

Beyond IceCube @ the South Pole. Outline Introduction: Optical vs. Radio & Acoustic Moving to the GZK scale: E n > 10 16 eV sensitivities Radio RICE Near-term future ideas ROCSTAR/DRM Surface array Acoustic Near-term future ideas SPATS

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Beyond IceCube @ the South Pole

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  1. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 n-induced charged particles • latt ~ 30m requires high module density • IceCube has r ~5000/km3 • To get sufficient statistics at higher energy scales (e.g., GZK scale), where one needs a fiducial volume closer to 100-1000 km3, need technology that is practical at lower module densities D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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,… D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  4. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  5. Focus on “Guaranteed” UHE Neutrinos • GZK flux models • Roughly speaking, depending on various assumptions, to detect one GZK n/yr at 1016-19 eV requires Veff ~ 4-50 km3 • See, e.g., Engel, Seckel and Stanev, Phys. Rev. D64 (2001) 093010 From Gorham et al., Phys. Rev. D72 (2005) 023002 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  6. Discovery Aperture vs. E Saltzberg, astro/ph 0501364 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  7. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  8. UHE Neutrino Radio Detection: RICE • Design • 20-channel array of dipole antennas • 100-300m depths • 200x200x200 m3 deployment volume • Analog readout into surface digitizers 10 cm 5 m D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  9. UHE Neutrino Radio Detection: RICE • Results (Kravchenko et al., astro-ph/0601148) • 1999-2005 RICE livetime of ~20500 hrs (Veff×livetime ~ 1-10 km3۰yr۰sr @ 1017-19 eV) • (Results from GLUE, ANITA, FORTE in the literature & at this workshop) D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  10. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  12. Possible ROCSTAR Node Configuration ≈50m D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  13. Possible ROCSTAR Block Diagram Antennas Local coincidence triggering D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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) D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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) D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  16. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 nm-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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 Ep>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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  19. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  20. UHE Neutrino-Induced Acoustic Signals • A n-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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

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

  24. SPATS Module Modules at DESY/Zeuthen Sensor Module One Full Module D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 km3 effective volume at GZK energies • ~100 strings on 1 km spacing grid • ~300 receivers per string (co-deployed with radio) D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  26. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 10-100PeV • 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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 200-600 m • 300 acoustic receivers, 5-1500 m • 2p acceptance, hadronic shower only (LPM stretches EM showers), Esh = 0.2E *See D. Besson et al., ICRC 2005 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  29. Hybrid IRA Simulation • Result: • Veff at E>1017 eV increased by a factor of 5-25 over IceCube alone (Veff > ~100km3) • ~20 GZK n events/year • Notes: • ESS flux, Gandhi s’s,  = 0.7 • For R, A, R+A • all flavors • NC and CC • For O** • only m Veff (km3) I=IceCube R=Radio A=Acoustic (GZK n’s/yr) Log10[En/eV] D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  30. Some Comments on UHE nt with IRA • High energy tau neutrinos are especially good candidates for coincident event capture; Veff 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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

  31. Beyond IceCube @ the South Pole Outline • Introduction: Optical vs. Radio & Acoustic • Moving to the GZK scale: En > 1016 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 nt sensitivities • Conclusions D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt 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 D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

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

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