Calculation methods for radio pulses from high energy showers

Abstract

We present an approximation for the numerical calculation ofČerenkov radio pulses in the Fraunhofer limit from very high energy showers in dense media.We compare it to full Montecarlo simulations in ice studying its range of applicability and show how it can be extended with a simple algorithm. The approximation reproduces well the angular distribution of the pulse around theČerenkov direction. An improved parameterization for the frequency spectrum in theČerenkov direction is given for phenomenolgical applications. We extend the method to study the pulses produced by showers at distances at which the Fraunhofer limit does not apply, and give the ranges of distances and frequencies in which Fraunhofer approximation is good enough for interpreting future experimental data. Our results are relevant for the detection of very high energy neutrinos with this technique. PACS number(s): 96.40. Pq; 96.40.Tv; 95.85.Bh; 13.15.+g

Measuring the BFKL pomeron in neutrino telescopes

“…If electron neutrinos are detected, the showers that come out of charged current interactions will have a different character depending on y because the neutrino induced electromagnetic (hadronic) shower arising at the leptonic (hadronic) vertex carries a fraction 1 − y (y) of the neutrino energy. In particular it has been recently suggested that it may be possible to measure y by using the radio technique [5]. This tecnique relies of the detection of coherent radio pulses from the excess charge in the induced showers in a dense medium such as ice.…”

“…The sensitivity to y arises from the elongation of the showers that develop at the electron vertex because of the Landau-Pomerančuck-Migdal (LPM) [24] effect [5].…”

“…These include the detection of particle shower fronts in the atmosphere in the horizontal direction (Horizontal Air Showers) [3] and coherent pulses from showers in different media, both acoustic [4] and in radio [4,5] waves. Shower detection is sensitive both to neutral current interactions and to all neutrino flavors.…”

Thinned simulations of extremely energetic showers in dense media for radio applications

“…Since the spectrum of Cherenkov radiation is approximately the Fourier transform of the distribution of excess negative charge [19,20], we assess the goodness of the thinning algorithms based on their ability to reproduce this distribution, reflected by the parameter set defined in Table 1. Of these, total excess tracklength T is the most useful, since it has very low intrinsic variability, and scales with the primary particle energy.…”

“…Tracking all 10 12 particles expected in a single EeV shower is infeasible with current technology. A parameterisation of the emitted radiation in ice at EeV energies was performed in the past exploiting the analogy with diffraction by a single slit by Fourier-transforming an approximate longitudinal and lateral profile of the shower [18][19][20]. Results for other 2 media were obtained using simple scaling relationships, which at TeV energies and for the regolith differ by ∼30% from the results obtained in full Monte Carlo simulations [16].…”