On the characteristics of individual cascade showers with the LPM effect at extremely high energies

Abstract

Characteristics of individual electromagnetic cascade showers in lead have been studied taking into consideration the Landau-Pomeranchuk-Migdal effect (LPM effect) through Monte Carlo simulation techniques. A total of 20 LPM showers have been simulated assumed to be initiated by photons or electrons of energy 1O"eV. We find that each of the twenty simulated showers shows multi-peak structure during its longitudinal development, unlike the smooth cascade a w e obtained for showers simulated using Bethe-Heitler cross sections. It is shown that thin detectors with a depth of only few tens of radiation lengths, though good far observing showers without the LPM effect, do not provide reliable information on the real development of the LPM shower in extremely high energy regions

One-dimensional hybrid approach to extensive air shower simulation

“…The MC treatment of the e/m cascade is realized by means of the EGS4 code [14], supplemented by an account of the Landau-Pomeranchuk-Migdal (LPM) effect [27,28,29] for ultra-high energy electrons (positrons) and photons. The simulation of photonuclear interactions and muon pair production was added to the EGS package closely following the CORSIKA implementation [9].…”

Cherenkov radio pulses from EeV neutrino interactions: the LPM effect

“…In charged current electron neutrino interactions the electron at the lepton vertex carries on average most of the energy [14] and the induced shower will also have a dominant electromagnetic character. Electromagnetic EeV showers in water or ice are dramatically affected by the Landau Pomeranchuck Migdal effect (LPM) [15,16] which is a manifestation of the collective electric field of matter at large distances [17][18][19]. In this work we consider the development of EeV electromagnetic showers in water and the implications for Cherenkov radiation both in the incoherent (optical) and coherent (radio pulses) regions which are respectively relevant for the conventional underground muon detectors and the radio technique for EeV neutrino detection.…”

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

“…for individual showers is appropriate. The exception is k L , where we find (not unexpectedly [29,31,32]) that variations from the mean fitted valuesk L are large, particularly at high energies. These fluctuations will dominate the radiation pattern in the regime where longitudinal decoherence dominates, which at the highest energies is everywhere except within a small fraction of a degree from θ C .…”

“…Also, and as we have previously mentioned, L is dependent upon the shower energy E 0 , so that the "constant" k L is in fact energy-dependent. For sufficiently low-energy showers, the dependence of L on E 0 is small, while at energies where LPM-elongation is significant (typically for E 0 E LP M ), L increases rapidly with E 0 [27,29,31,32]. Thus we expectk L to be fit well by the following relation:…”