ICRC2015

July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

Intensity of Microwave Signals Expected from Molecular Bremsstrahlung Radiation in Extensive Air Showers

Aug 4, 2015, 4:00 PM
1h
Amazon Foyer (World Forum)

Amazon Foyer

World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 212
Poster contribution CR-EX

Speakers

Imen Al Samarai Olivier Deligny (CNRS/IN2P3)

Description

A potential detection technique of ultra-high energy cosmic rays would be the use of the molecular Bremsstrahlung radiation emitted by low-energy electrons left after the passage of the showers in the atmosphere. The emission mechanism is expected from quasi-elastic collisions of electrons produced in the shower by the ionisation of the molecules in the atmosphere. Given the low energy of the ionisation electrons, GHz photons resulting from this emission mechanism are expected to be emitted isotropically. This would allow for mapping the ionisation content along the showers through the intensity of the microwave signals detected at ground, in the same way as done for the fluorescence technique. In this contribution, a detailed calculation of the spectral intensity of photons at ground level originating from the transitions between unquantised energy states of free ionisation electrons is presented. The obtained spectral intensity is shown to be $\simeq 4.0~10^{-26}~$W m$^{-2}~$Hz$^{-1}$ at 10 km from the shower core for a vertical shower induced by a proton of $10^{17.5}~$eV. In addition, the contribution of the high-energy electrons of the showers to the GHz spectral intensity through Bremsstrahlung emission is shown to be of the same order or even dominant during the first nanoseconds at distances sufficiently close to the shower core. The detectability of the derived spectral intensities with the current experimental setups is discussed.
Registration number following "ICRC2015-I/" 474 -- not specified --

Co-author

Olivier Deligny (CNRS/IN2P3)

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