Internal pair creation induced by nuclear coulomb excitation in heavy-ion collisions

摘要: Abstract Internal electron-positron pair creation caused by nuclear Coulomb excitation in heavy-ion collisions is compared with the spontaneous and induced positron production overcritical quasimolecules Z1 + Z2$˛170. Using rotation-vibration model calculation of quadrupole conversion coefficient for formation, total cross section system 23892U-23892U was found to be σ C e , − = 0.125 mb at Ekinc.m. 797 MeV, which four times smaller than ind corresponding vacuum decay process if a K-shell vacancy L0 10− assumed. Evaluation ratio R d ( ϑ c.m. ) / between differential sections respect ion angle ϑc.m leads 60 ϑc.m. 160°. In contrast spectrum, excited levels U not followed positrons kinetic energy above 0.9 MeV. Therefore unique determination fields experimentally possible provided that drastically reduced. addition, similar calculations have been performed resulting from systems U-Cf, Th-Th, Pb-Pb, Ni-Ni, Xe-Ba, Xe-Nd Xe-Ce. The occupation vacant bound states superheavy electronic molecules electrons γ-rays transitions Eγ