Fission from Fe and Nb reactions with heavy targets at 50–100 MeV/nucleon

Abstract

Cross sections, parallel and perpendicular momentum transfers, charge loss, and velocity systematics are presented for fission following reactions of Fe and Nb projectiles at 50-100 MeV/nucleon on targets of Ta, Au, and Th. Data are compared to simple models for peripheral heavy ion collisions. PACS number(s): 25.70. Jj, 25.70. -z, 25.85.Ca

Electromagnetic and nuclear fission of238U in the reaction of 100, 500, and 1000 A�MeV208Pb with238U

“…This result differs from the projectile-energy dependence of the ratio O'fiss/O'geo m at lower energies as given in [ 10], where the fission probability [10] included the reaction of uranium and thorium targets with different projectiles having total energies 0.3 to 10GeV. The fission probability dropped to a value of about 0.2 at 10 GeV total energy.…”

“…The increase of the parallel-momentum transfer can be understood in the concept of a limiting excitation energy up to which fission occurs, as, for example, proposed by Saint-Laurent et al [14]. According to [10] the simple relation between the excitation energy E* and the mean parallel-momentum transfer <Pll >, E* Pll E~N PlICN is assumed, with E*cN being the excitation energy of the compound nucleus (if the complete fusion would occur) and PlICN the parallel momentum of the compound nucleus. This relation, which was experimentally confirmed, originates from intranuclear cascade calculations which lead to the linear relation between the excitation energy of the fissioning nucleus and the parallel momentum transfer (see [11]).…”

“…These nuclei are produced in grazing collisions of the 23SU and 2~ nuclei, and, obviously, the mass and the atomic number of the fissioning nucleus is a function of the number of protons and neutrons lost in the primary interaction of the colliding nuclei. Experimental studies [10] and intranuclear-cascade calculations [11] show no correlation between the parallel-and perpendicular-momentum transfer, and they also show that the excitation energy of the recoil nucleus depends linearly on the parallel-momentum transfer. Therefore, the mass loss is also proportional to the parallel-momentum transfer.…”

“…The choice of F(Pll) is somewhat arbitrary, though it can be justified, for example, by the experimental data of [10] on the parallel-momentum transfer. In the following we discuss the possible effect of F(Pll) on the decomposition of the nuclear and electromagnetic parts.…”

“…Therefore, the mass loss is also proportional to the parallel-momentum transfer. Using the data of [10] we implemented into our Monte Carlo simulation the number of nucleons knocked out of the 23Su nucleus as a function of the parallel-momentum transfer PlI, thus taking into account the contribution coming from various fissioning nuclei.…”