Screening effects in electron–positron pair production with capture in ultrarelativistic collisions

Abstract

We study the influence of the shielding of the atomic nucleus by atomic electrons on positron–electron pair production with capture in ultrarelativistic nucleus-atom collisions. The importance of the shielding is shown to increase with the collision energy and with the atomic number of the target atom. We report calculations of cross sections for the pair production with capture in collisions of 160 GeV/nucleon Pb 82+ projectiles with different atomic targets ranging from Be to Au. Depending on the atomic number of the target the shielding is shown to reduce the cross sections by 2.5–14 percent at this collision energy.