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Radio Detection of High-Energy Neutrinos: Goals, Deployment, and Data Analysis

This study focuses on the radio detection of high-energy neutrinos from astrophysical sources. It covers the deployment status, event rate calculation, simulation of signal generation, detector response, background analysis, and data summary from August 2000. Results from simulations and data analysis are presented, along with systematic effects and potential improvements in limits and measurements.

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Radio Detection of High-Energy Neutrinos: Goals, Deployment, and Data Analysis

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  1. astro-ph/0206371

  2. Outline • Concept * • Deployment Status • Event Rate Calculation • Interaction rate * • Simulation of signal generation * • Propagation * • Detector response • Veff * • Event Reconstruction • Backgrounds & Filters * • August 2000 data • Data summary * • Limits * • Discussion • Systematics * • LPM & hadronic showers *

  3. Radio Detection of High Energy Neutrinos * Goals PeV: AGN 1 km3 EeV: GZK 103 km3 Cherenkov radiation from n-induced in-ice shower S ~ DQ ~ 0.25 Es/GeV l ~ RM ~ 10 cm Transparency > 1 km Thermal noise @ 250 k

  4. Pole: Deployment • 16 Rx (10 cm dipole) • 5 Tx • 3 Horns • 4 Oscilliscopes (x4) • DAQ • PCs • Pulse Generator • Dry hole Kansas: • Network analyzer • Antenna range

  5. Interactions and shower simulations * • Interaction Model • ne isotropic from upper hemisphere (2p) • charged current only • Gandhi et al. ’98 cross-section ds/dy with ~20% reduction for Oxygen (EMC effect) • Shower simulation • GEANT 3.21 30% smaller than ZHS (but …GEANT 4 ??) • LPM from Alvarez & Zas • no contribution from hadronic cascade

  6. Radio Attenuation in Ice * e = e’ + i e” Red – Westphal (Greenland) + Matsuoka (high freq) Black – Kawada(lab) + Matsuoka (high freq) (from Matsuoka) RICE bandpass Solid – Provorov (used by RICE) Dashed – Matsuoka + Westphal RICE bandpass

  7. Pulse shape simulation * A lot of work has gone into calibration of antennas, amps, cables, DAQ. See astroph/0112372 Background taken from data sample Disc. threshold

  8. Results of MC simulation * 60,000 e- showers at E = 1 EeV Black dots – sample Red dots – location of events which trigger RICE ~ 5% efficiency Limited by attenuation Limited by Cherenkov angle

  9. RICE effective volume for e-,g showers * Multiply by 2p sr Range due to varying attenuation by 0.5-2 Range due to varying signal strength by 0.5-2

  10. Reconstruction & Man made noise This is actually a transmitter event ! • dt =50 ns for noise • dt = 25 ns for n • dr = 10 m nearby • dr = 0.1 R , < 1 km • dq ~ 10 deg • dE/E ~ 0.5

  11. Thermal Background * Red – Simulated detected showers (1 EeV) Black – Simulated noise – uncorrelated background Warnings: shower vertices are “true” positions not reconstructed. Should be OK inside 1 km. shower vertices are monoenergetic.

  12. Results of Data Analysis * 333.3 hrs livetime

  13. Limits on diffuse ne flux from e- showers * • Stecker & Salamon (AGN) • Protheroe (AGN) • Mannheim (AGN) • Protheroe & Stanev (TD) • Engel, Seckel & Stanev (GZK) • Ranges are central 80% AMANDA (Hundtermark)

  14. Potential Systematic Effects *

  15. LPM and hadronic showers * “Hadronic” Es = 20% En Without LPM With LPM

  16. Limits on power law fluxes PRELIMINARY Top set: ne CC only Bottom set: all n’s CC+NC AMANDA (Hundtermark) GZK challenge!

  17. Summary • Radio detection has a bright future • Demonstrated ability to reject surface backgrounds and work close to thermal limit • Major uncertainty is • attenuation in ice (high energy) • calibration (low energy) • Veff (E > 1018eV) > 20 km3 sr [ne CC only] • Limits will improve by 4-10 with inclusion of hadronic channels • Limits may improve by 10 (again) with analysis of 1 yr data.

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