Advancing UHE Neutrino Detection at the South Pole

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

SPATS Module Modules at DESY/Zeuthen Sensor Module One Full Module D.F. Cowen/IceCube Collab. Beyond IceCube Beijing UHE nt Workshop

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

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

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

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

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

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

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

Advancing UHE Neutrino Detection at the South Pole

Advancing UHE Neutrino Detection at the South Pole

Presentation Transcript

A km 3 Neutrino Telescope: IceCube at the South Pole

The South POLE

Mr. Monkey Goes to the South Pole

North pole south pole

The ‘race to the South Pole ’

Unsupported 850 miles to the South Pole

SOUTH Pole

IceCube: Exploring the Universe from the South Pole with high energy neutrinos

The South Pole Telescope Readout System

The MOF at South Pole

AMANDA and IceCube neutrino telescopes at the South Pole

South Pole Ice (SPICE) model

South Pole Ice model

Neutrino Astronomy at the South Pole

The South Pole – One Degree of Separation

Neutrino Astronomy at the South Pole

Science from the South Pole

Simulation Studies for Cosmic Neutrino Detection with IceCube++ at the South Pole

News from the South Pole: Recent Results from the IceCube and AMANDA Neutrino Telescopes

Unsupported 850 miles to the South Pole

SOUTH Pole

South Pole Ice model