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Detection and Calorimetry of High Energy Particles with Cherenkov and Transition

Detection and Calorimetry of High Energy Particles with Cherenkov and Transition Radiation at Radio Frequencies David Saltzberg UCLA March 28, 2002. Applications to Astrophysical Neutrino Detection. Is there a neutrino component to the UHECR? Radio can instrument largest volumes

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Detection and Calorimetry of High Energy Particles with Cherenkov and Transition

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  1. Detection and Calorimetry of High Energy Particles with Cherenkov and Transition Radiation at Radio Frequencies David Saltzberg UCLA March 28, 2002

  2. Applications to Astrophysical Neutrino Detection Is there a neutrino component to the UHECR? Radio can instrument largest volumes Note, unlike muon trackers, radio gives a measurement of total shower energy

  3. Basic Questions • Does the 20-30% charge excess predicted by Askaryan really develop? • Does this excess charge emit 100--2500 MHz CR (and TR) as needed by various experiments? • Can we count on the coherence factors of • 106 -- 1011? ==> Implications for high-energy neutrino detection

  4. Two Accelerator Experiments • Lunacee-I: Argonne Wakefield • ANL: Paul Schoessow, Wei Gai, John Power, Dick Konecny, Manuel Conde • JPL: Peter Gorham • UCLA: David Saltzberg • Phys. Rev. E62, 8590 (2000) • Lunacee-II: SLAC -FFTB • SLAC: Dieter Walz, Al Odian, Clive Field, Rick Iverson • JPL: Peter Gorham, George Resch • UCLA: David Saltzberg, Dawn Williams • Phys. Rev. Lett. 86, 2802 (2001)

  5. Argonne setup Circular Geometry to measure angle of emission TR from interfaces CR from beam in sand

  6. Beam in Target Stopping distance in sand ~ 6cm 1010 -- 1011 electrons per bunch 99.8% SiO2 density=1.58; n=1.6 tan  ~ 0.008

  7. Trigger/DAQ • Trigger from S-band dipole near vacuum window (<<40psec jitter) Typical pulses ~10V pk-to-pk ==> No amplifiers, just attenuators. Voltage (ie, field) measured directly by TDS694 -- 3GHz, 10GSa/s oscilloscope

  8. Target Empty-- Pure TR Shape follows TR expectation Factor 6 in E-field discrepancy -- Not understood. Returning to AWA this summer Not well suited for CR measurements or for charge excess-->go to SLAC

  9. Askaryan runs: SLAC-FFTB • Improvements over Lunacee -I • To produce asymmetry predicted by Askaryan==> use a higher energy beam • Need a longer shower ==> use a higher energy beam • To avoid TR ==> Use photons • SLAC FFTB • 28.5 GeV electrons on 1%,2.7% X0 • Photon bremsstrahlung beam with <E>~3 GeV • Still has tight bunch (<1mm) August 2000

  10. SLAC FFTB Angled face to prevent TIR

  11. The “Kitty Litter” Experiment 7000 lbs dry sand

  12. Antenna Frequency heff Buried Dipoles 0.2—1.8 GHz 5—25 cm S-Band Horn 1.7—2.6 GHz 18 cm C-Band Horn 4.5—5.4 GHz 6 cm Electric Field Measurement E = V/heff referenced to 1m S-Band Horn “bandwidth-limited” pulse: t ~ 1/BW=1nsec reflections>4nsec w/no radiators, see mV

  13. Backgrounds? • SLAC is an S-band accelerator---RF background? Electron beam on/ with no radiators (no photon beam) ==> ~0.020 V/pk-to-pk • Electron beam on/ with 1% radiator ==> ~100 V/pk-to-pk Monitor potential TR with extra horn

  14. Polarization S-band Horn Measure polarization using Stokes parameters averaged over 0.5 ns, (assuming no circular) Expect linear (radial) polarization (0 deg. in this case) Reflections destroy polarization

  15. Coherence: Expect slope of 1.0 for E-field S band Slope = 0.96 +/- 0.05 Bremsstrahlung beam==> cannot count number of beam particles. Use total energy deposited instead (allows easier comparison to parameterizations)

  16. Shock wave Dipole buried insand along line parallel to beamline Cherenkov radiation is a shock wave ==> dipoles should “fire” at v=c, not c/n v/c = 1.0 +/- 0.1

  17. Cherenkov Cone Emission at Cherenkov angle

  18. S band profile Move S band horn along wall Peak corresponds ~ shower max. as shower excess approximately does KNG param.

  19. Tests of Total Internal Reflection • Compare emission from inclined face to parallel face. n=1 (900 - CR) = TIR n CR Ratio of electric fields ==> at least 50x suppression (2500 in power)

  20. Absolute field strengths • Antennas pointing at shower max • ~200-800 MHz -- RICE dipole • 1.2 - 2.0 GHz -- small dipole • 1.7--2.6 GHz -- S band horn • 4.4-- 5.6 GHz -- C band horn • Prediction from Alvarez-Muniz, Vazquez, Zas (2000). [will add Buniy,Ralston (2000)] • near-field etc. corrections <~1 dB • scaled by 0.5 for partial view • scaling from ice to sand • Assumes initiated by single particle not beam of lower energy photons 1.0 0.1 V/m/MHz

  21. Conclusions • CR and TR be used for detection of EHE showers. • Some theoretical questions remain • quenching at extremely high energies? • Askaryan effect is confirmed by absolute intensity, polarization, frequency dependence, coherence • Ongoing and Proposed Experiments: • Ethr (moon) ~ 1020 eV as expected , possibly lower • Consistent with thresholds ~1016 for south pole (RICE) • Salt domes offer potential as a radio Cherenkov detector ~1016 • ANITA: antarctic satellite proposed.

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