G. Marikyan

Kaon, pion, and proton associated photofission of Bi nuclei

The first measurement of proton, pion, and kaon associated fission of Bi nuclei has been performed in a photon energy range 1. 45 < Eγ < 1. 55 GeV. The fission probabilities are compared with an inclusive fission probabilities obtained with photons, protons and pions. The fission probability of Bi nuclei in coincidence with kaons is 0. 18 ± 0. 06 which is ∼3 times larger than the proton and pion associated fission probabilities and ∼2 times larger than inclusive ones. The kaon associated excess fission events are explained in terms of bound Λ residual states and their weak nonmesonic decays.

Heavy-nucleus multifragmentation induced by coherent bremsstrahlung photons with endpoint energy E γ max =4.1 GeV

New experimental data are presented that were obtained by studying the multifragmentation of 197Au, 209Bi, 238U, and 243Am nuclei in a coherent bremsstrahlung-photon beam with an endpoint energy of 4.1 GeV from the Erevan Synchrotron. For the first time, four or more fragments are observed. For all the nuclei studied here, the respective production cross sections are about (1–3)×10−3 of the total inelastic photon-nucleus cross section. The fragment yields are isotropic.