Electron–positron pair production by photons: A historical overview

Abstract

This account briefly traces the growth of our theoretical and experimental knowledge of electron-positron pair production by photons, from the prediction of the positron by Dirac [1928a can interact with the Coulomb field of an atomic nucleus to be transformed into an electron-positron pair, the probability increasing with increasing photon energy, up to a plateau at high energies, and increasing with increasing atomic number approximately as the square of the nuclear charge (proton number). This interaction can also take place in the field of an atomic electron, for photons of energy in excess of 4m e c 2 (2.044 MeV), in which case the process is called triplet production due to the track of the recoiling atomic electron adding to the tracks of the created electron-positron pair. The last systematic computations and tabulations of pair and triplet cross sections, which are the predominant contributions to the photon mass attenuation coefficient for photon energies 10 MeV and higher, were those of Hubbell et al. [Pair, triplet, and total atomic cross sections (and mass attenuation coefficients) for 1 MeV-100 GeV photons in elements Z ¼ 1-100. J. Phys. Chem. Ref. Data 9, 1023Data 9, -1147, from threshold (1.022 MeV) up to 100 GeV, for all elements Z ¼ 1-100. These computations required some ad hoc bridging functions between the available low-energy and high-energy theoretical models. Recently (1979Recently ( -2001, Sud and collaborators have developed some new approaches including using distorted wave Born approximation (DWBA) theory to compute pair production cross sections in the intermediate energy region (5.0-10.0 MeV) on a firmer theoretical basis. These and other recent developments, and their possible implications for improved computations of pair and triplet cross sections, are discussed. Published by Elsevier Ltd.

Production Yield of Muon-Induced Neutrons in Lead

“…This is in mild tension with earlier results from CRESST-II [62], both in the analysis provided by the CRESST collaboration [63] and in the analysis by A. Brown et al [135], as they partially exclude the potential WIMP signals from [63]. To investigate this situation further, the experiment was recently upgraded to reduce the still high background contribution: depending on the chosen likelihood maximum, a background of 37.6 events or 42.8 events remains, mainly recoiling nuclei and α-particles from α-decay [63].…”

Black hole squeezers

“…A similar statement applies to electromagnetic waves: electron-positron pairs cannot be produced by plane electromagnetic waves, no matter how strong we make the electromagnetic field [17]; otherwise momentum conservation would be violated. However, pair production of electrons and positrons is possible if a nucleus is introduced to balance the momentum [18].…”

Strong suppression of Coulomb corrections to the e + e − pair production cross section in ultrarelativistic nuclear collisions

“…[32,33] were obtained only for ω < 5M eV . In a set of later publications [34,35,36,37] (see also reviews [38,39]) the magnitude of σ γA (ω) has been obtained for higher values of ω and several Z A . In the high-energy region ω ≫ m, the consideration is greatly simplified.…”