Electromagnetic Interactions of High Energy Cosmic Ray Muons

Abstract

This paper investigates the electromagnetic interactions of muons. The various processes such as knock‐on electron‐, bremsstrahlung‐, direct electron pair production, and nuclear interactions are described in detail. The energy range concerned extends from 109 eV up to 1015 eV for primary muons and from 108 eV up to 1014 eV for energy transfers to the secondaries. On the one hand the measurement of muon interactions represents a test of quantum electrodynamics. On the other hand the high energies available in cosmic rays would possibly lead to the measurement of new processes or the detection of new particles. One hopes to find in the high energy domain the answer to the question why the muon exists at all and if there are properties (apart from differences in mass, lifetime, and lepton number) which distinguish it from a mere heavy electron. The different experimental techniques are described and the various experimental results on muon interactions are presented and compared with relevant QED‐theories. Observed deviations between theory and experiment and anomalies in muon interactions are critically investigated and discussed in the light of experimental difficulties and interpretation problems. In general, agreement between theory and experiment is found, i.e. QED‐theories describe the results adequately. However, some experiments claim to have detected anomalies in muon physics in the cosmic ray beam. But the hypotheses on new processes and new particles in the high energy range do not withstand a critical analysis. It is concluded that the observed deviations can be understood in the framework of conventional theories.

Observation of electromagnetic interactions of high energy muons deep underground

“…8, the event distribution of the number of hits has been turned into the transferred energy distribution (1). The weighted average energy E corresponding to a certain number of hits was calculated similarly to relation (2). The experimental points in the figure are plotted as deviations from the expectation taking into account all corrections.…”

“…A comprehensive survey of the different techniques used for muon cross section investigations in cosmic rays and a critical analysis of the earlier experimental results may be found in [2]. Two methods are most widely applied to check the energy dependence of the muon interaction cross section.…”

Production Yield of Muon-Induced Neutrons in Lead

“…The CoGeNT collaboration plans to further investigate the observation with the C-4 upgrade. Its aims are: an increase of the target mass to four PPCs of up to 1.3 kg mass each, a lowering of the threshold, an improved muon veto, and an increased shielding against γand neutron background [126]. 36 2 Searching Dark Matter: The Quest for the Missing Mass…”

“…3 report the available data compilations in Sect. 3.2.7, following the outline of [6,65,125,126]. The parametrization of the effective energy loss for the LSM rock is given in Sect.…”

“…It is related to the mean energy loss Eq. 3.11a via [6, p. 330], [32,42,126,154] [113, p. 76]. 2 Again, the definition is not consistent in the literature: In [42] a is split into a contribution from the knock-on electrons, and a contribution from ionisation and excitation.…”