Čerenkov radio pulses from electromagnetic showers in the time domain

Abstract

The electric field of theČerenkov radio pulse produced by a single charged particle track in a dielectric medium is derived from first principles. An algorithm is developed to obtain the pulse in the time domain for numerical calculations. The algorithm is implemented in a Monte Carlo simulation of electromagnetic showers in dense media (specifically designed for coherent radio emission applications) as might be induced by interactions of ultra-high energy neutrinos. The coherenť Cerenkov radio emission produced by such showers is obtained simultaneously both in the time and frequency domains. A consistency check performed by Fourier-transforming the pulse in time and comparing it to the frequency spectrum obtained directly in the simulations yields, as expected, fully consistent results. The reversal of the time structure inside theČerenkov cone and the signs of the corresponding pulses are addressed in detail. The results, besides testing algorithms used for reference calculations in the frequency domain, shed new light into the properties of the radio pulse in the time domain. The shape of the pulse in the time domain is directly related to the depth development of the excess charge in the shower and its width to the observation angle with respect to theČerenkov direction. This information can be of great practical importance for interpreting actual data.PACS numbers: 95.85. Bh, 95.85.Ry,

Near-field radio emission induced by extensive air showers

“…1 (left) that the pulsed fields for the acceleration and deceleration of the track in this configuration using Eq. (2.1) are the same as those obtained with the well-known ZHS time formula [13] (radiation field calculated in the Coulomb gauge). Not taking into account the charge conservation results in an unphysical field (green line) that differs from the Coulomb gauge calculation.…”

SELFAS2: Radio emission from cosmic ray air showers. Effect of realistic air refractive index

“…(although we use here the Lorentz gauge, a similar and more detailed demonstration is available in [24], using a coulombian gauge). When θ i approaches the Cerenkov angle θ Cer i , the numerator and the denominator in Eq.8 both vanish.…”

LUNASKA neutrino search with the Parkes and ATCA telescopes

“…The radio pulse from a particle cascade is known to have a bipolar shape from both simulation [26] and experiment [27], indicating that the phase of the pulse is ±π/2. However, in our experiment we converted the signal from radio frequency (RF) to intermediate with a local oscillator signal: this adds the unknown phase of the local oscillator to the phase of the pulse, effectively randomising it, so it is not possible to design a filter to match it [28].…”