A high energy shower

High-Energy Phenomena in Nuclear Emulsions

“…They have also measured the trident cross section 17 between 0.1 and 10 Bev and find it in agreement with the theoretical value of the cross section as calculated by Bhabha, 23 Nishina, 24 and Racah. 25 Koshiba and Kaplon, 18 ' 19 Debenedetti et al 20 and Lohrmann 21 have measured the trident cross section and find an anomalously large cross section at high energies. Leonard, 22 using 440-Mev electrons, has found the measured cross section to be in agreement with the theoretical value at this energy.…”

“…Our preliminary report on this shower 8,9 ' 15 stressed the rapid shower development and the high trident cross section (direct pair production by an electron). Other workers [16][17][18][19][20][21][22] have investigated this problem with conflicting results. Block and King 16 have calculated the fraction of bremsstrahlung pairs which will materialize so close to the track of the parent electron as to be mistaken for a trident (so-called pseudotridents).…”