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Ultra-high energy neutinos generated in GZK(Greisen- Zatsepin - Kuzmin ) Process

Measurement of a phase of a radio wave reflected from rock salt and ice irradiated by an electron beam for detection of ultra-high-energy neutrinos.

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Ultra-high energy neutinos generated in GZK(Greisen- Zatsepin - Kuzmin ) Process

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  1. Measurement of a phase of a radio wave reflected from rock salt and ice irradiated by an electron beam for detection of ultra-high-energy neutrinos • Masami Chiba, Toshio. Kamijo, Takahiro Tanikawa, Hiroyuki Yano, Fumiaki Yabuki, Osamu Yasuda, Yuichi Chikashige*, Tadashi Kon*, Yutaka Shimizu*, Shunichirou Watanabe*,Michiaki Utsumi**, and Masatoshi Fujii*** • Tokyo Metropolitan University, • Seikei University*, Tokai University**, Shimane University*** • Talk at ARENA2012 – June 20, 2012

  2. Log E(dN/dE) [km-2 yr-1 (2pi sr)-1] Ultra-high energy neutinos generated in GZK(Greisen-Zatsepin-Kuzmin)Process p +  (2.7K)+ n + + p e-e + e +e Ultra-high-energy cosmic ray is generated in Active Galactic Nuclei Gamma-ray Burst etc. Protons （E>4*1019eV ） GZK n ― Galactic GZK threshold ・　Detection of cosmic ν（1016～1021eV) using a rock salt formation or the Antarctic ice sheet 。 • The flux is extremely low (≒1/ km2・day), we need a gigantic mass of the detection medium of 50 Gt(≒ 10 events/year) a million times as large as Super Kamiokande.

  3. Radar method and a coaxial tube for ice and rock salt Coaxial tube with 2 cm diameter

  4. Electron beam irradiation on ice or rock salt • ・Cockcroft-Walton accelerator located at Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency Electron beam 10cm Cooling box 30cm Electron beam Range 1cminice Coaxial tube

  5. Electron beam 2MeV1mA Cooling box Coaxial tube 20mm φ Dry ice Coaxial tube and radio-wave reflection • ・Coaxial tube was filled with ice or rock salt. • ・2MeV electron beam irradiate • the open end of the coaxial tube. • (4 J/s = 2×1019 eV/s at 1mA) • ・Temperature rise(ΔT) • → Increase of refractive index(Δn) • → Radio wave reflection changes Temperature rise Thermo couple 435MHz Radio wave Ice or rock salt

  6. Power reflection rate with a change of refractive index Matzler, C and Wegmuller, U., J. Appl. Phys. 80, 1623-1630(1987) Matsuoka,T, Fujita, S and Mae, S., J. Appl Phys. 80,5884-5890(1996) n ・for ice and rock salt Power reflection rate(Γ) is proportional to ΔT2 Fresnel equation : Irradiation Γ=

  7. Electronics Rb oscillator:10MHz 435.000 000 00MHz -10dBm = 10-4 W Oscillator SMF100A Circulator Electron beam Coaxial tube Splitter Null method Thermo-couple Spectrum analyzer Specat2 Variable Phase shifter combiner Directional coupler NI LabVIEW system Directional coupler PC Detector Amplifier DAC ADC PC Record phase Real-time spectrum analyzer RSA3303B

  8. Amplitude and Phase Amplitude measurement • Before irradiation: automatic tuning of is ON = + • reference reflected wave Oscillator 435MHz Circulator • At irradiation: automatic tuning OFF Splitter = + reflected • reference reflected wave = - 1) reference Variable phase shifter Combiner =2 Automatic tuning LabVIEW system Phase measurement Before and at irradiation: automatic tuning ON Detector Splitter RSA3303B Due to open end of coaxial tube Reference Reflected wave Is measured then

  9. Irradiation room over the wall Receiver Rboscillator Realtimespectroanalyzer Oscillator NI ELVIS LabVIEW controller

  10. Frequency domain spectrum • Rejection of noises from electric power source of 50 Hz. Data analysis of Real Time Spectrometer • Time domain data of 1024points×5 for 640 ms • 1 datum for 128ms • Conversion of time domain to frequency domain by FFT

  11. Reflection phase and ratein Ice

  12. Calculation of phase difference of reflected wave by a model (based on Telegrapher’s equation) Electron beam 10mm Axial tube Phase difference Δφ between Γ1 and Γ2

  13. Comparison of phases between experiment and calculation

  14. Reflection rate calculated by measured phase Electron beam 2MeV 1mA

  15. Power reflection rate vs. square of temperature

  16. Summary ・We found radio wave reflection from ice as well as rock salt with electron beam irradiation. ・Constructing an automatic-negative-feedback circuit in which variable phase shifter was tuned to get the null output, we measured the phase of the reflected-radio wave. ・The reflected amplitude was reproduced by the measured phase and was explained by a model in which the temperature is taken into account. ・Due to the long memory time, a stand-alone-GZK-neutrino detector could be constructed with a peak power of 1 GW (Equivalent Isotropic Radiation Power) radar supplied by a phased array antenna on a surface. ・Rock salt formation, Antarctic ice sheet and the moon crust would be candidates for the detector media. ・A new radiation detector “Radar Chamber” is established utilizing for all dielectric media. It is not only for radiation detection but also for other purposes using materials with inhomogeneous refractive index in space and time.

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