Observation of Radar Echoes from High-Energy Particle Cascades

Tau neutrinos are expected to comprise roughly one third of both the astrophysical and cosmogenic neutrino flux, but currently the flavor ratio is poorly constrained and the expected flux at energies above 10 17 eV is low. We present a detector concept aimed at measuring the diffuse flux of tau neutrinos in this energy range via a high-elevation mountaintop detector using the radio technique. The detector searches for radio signals from upgoing air showers generated by Earthskimming tau neutrinos. Signals from several antennas in a compact array are coherently summed at the trigger level, permitting not only directional masking of anthropogenic backgrounds, but also a low trigger threshold. This design takes advantage of both the large viewing area available at high-elevation sites and the nearly full duty cycle available to radio instruments. We present trade studies that consider the station elevation, frequency band, number of antennas in the array, and the trigger threshold to develop a highly efficient station design. Such a mountaintop detector can achieve a factor of ten improvement in acceptance over existing instruments with 100 independent stations. With 1000 stations and three years of observation, it can achieve a sensitivity to an integrated E −2 flux of < 10 −9 GeV cm −2 sr −1 s −1 , in the range of the expected flux of all-flavor cosmogenic neutrinos assuming a pure iron cosmic-ray composition.

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“…(A. 19) In Table 2, we compare the values resulting from numerical integration of Equation 3.4 and the results of MHP14 (Equation A. 19).…”

Section: A2 Geometric Acceptancementioning

confidence: 99%

“…19) In Table 2, we compare the values resulting from numerical integration of Equation 3.4 and the results of MHP14 (Equation A. 19). The discrepancies are large for lower elevations and narrower θ d cuts (θ cut ) while agreement is at the 1% level for high altitudes and narrow θ d , which was the focus of MHP14.…”

Section: A2 Geometric Acceptancementioning

confidence: 99%

Prospects for high-elevation radio detection of 0>10 PeV tau neutrinos

Wissel

Romero-Wolf

Schoorlemmer

et al. 2020

J. Cosmol. Astropart. Phys.

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“…The above model is incorporated into a software package called RadioScatter [24], which is open source and has been successfully run on several different flavors of linux. The module is written in C++ and can be incorporated into user scripts or large Monte-Carlo packages such as GEANT4.…”

Section: Radioscattermentioning

confidence: 99%

Particle-level model for radar based detection of high-energy neutrino cascades

Prohira

Besson

2019

Nuclear Instruments and Methods in Physics Research Section A:

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We present a particle-level model for calculating the radio scatter of incident RF radiation from the plasma formed in the wake of a particle shower. We incorporate this model into a software module ("RadioScatter"), which calculates the collective scattered signal using the individual particle equations of motion, accounting for plasma effects, transmitter and receiver geometries, refraction at boundaries, and antenna gain patterns. We find appreciable collective scattering amplitudes with coherent phase for a range of geometries, with high geometric and volumetric acceptance. Details of the calculation are discussed, as well as the implementation of RadioScatter into GEANT4. A laboratory test of our model, currently scheduled at SLAC in 2018, with the goal of measuring the time-dependent characteristics of the reflecting plasma, is also described. Prospects for a future in-ice, high-energy neutrino detector, along with comparison to current detection strategies, are presented.

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“…Here we present a new technique designed to instrument large volumes of high density media and provide an approach complementary to those currently employed. The radar echo technique enables the detection of particle cascades initiated within large volumes of high density media [4][5][6][7]. We anticipate good sensitivity to neutrino initiated cascades with primary energies exceeding >10 PeV, and therefore offering considerable overlap with existing experiments.…”

Section: Introductionmentioning

confidence: 99%

Simulation and Optimisation for the Radar Echo Telescope for Cosmic Rays

Allison

Beatty

Besson³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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The SLAC T-576 beam test experiment showed the feasibility of the radar detection technique to probe high-energy particle cascades in dense media. Corresponding particle-level simulations indicate that the radar method has very promising sensitivity to probe the >PeV cosmic neutrino flux. As such, it is crucial to demonstrate the in-situ feasibility of the radar echo method, which is the main goal of the current RET-CR experiment. Although the final goal of the Radar Echo Telescope is to detect cosmic neutrinos, we seek a proof of principle using cosmic-ray air showers penetrating the (high-altitude) Antarctic ice sheet. When an UHECR particle cascade propagates into a high-elevation ice sheet, it produces a dense in-ice cascade of charged particles which can reflect incoming radio waves. Using a surface cosmic-ray detector, the energy and direction of the UHECR can be reconstructed, and as such this constitutes a nearly ideal in-situ test beam to provide the proof of principle for the radar echo technique. RET-CR will consist of a transmitter array, receiver antennas and a surface scintillator plate array. Here we present the simulation efforts for RET-CR performed to optimise the surface array layout and triggering system, which affords an estimate of the expected event rate.

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Observation of Radar Echoes from High-Energy Particle Cascades

Cited by 41 publications

References 57 publications

Prospects for high-elevation radio detection of 0>10 PeV tau neutrinos

Prospects for high-elevation radio detection of 0>10 PeV tau neutrinos

Particle-level model for radar based detection of high-energy neutrino cascades

Simulation and Optimisation for the Radar Echo Telescope for Cosmic Rays

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