Angular distribution of preequilibrium neutron emissions from heavy-ion reactions

Abstract

The angular distribution of preequilibrium nucleons emitted in low-and medium-energy heavy-ion reactions is determined from the kinematics of nucleon-nucleon scattering inside the nuclear matter. In calculating the scattering kernels the excitation of the nuclear matter has been taken into account through a finite-temperature Fermi distribution of the nucleons. Neutron angular distribution in 12 Cϩ 165 Ho reaction at 300 MeV incident energy and 20 Nϩ 165 Ho reaction at 600 MeV is calculated from two-body scattering kinematics and compared with the experimental data. The present calculations reproduce the experimental data fairly well in both cases.

Neutron dosimetry in the particle accelerator environment

“…This situation would suggest that PEQ emission will not occur at such low energies for nucleon (or possibly alpha) induced reactions. Calculated results from our earlier developed heavy ion reaction model code HION (Nandy et al, 1999) fit the experimental results well.…”

“…Theoretical analysis and developments (Sarkar and Nandy, 2000;Nandy et al, 1999;Dhar et al, 2003b;Maity et al, 2005;Tripathy et al, 2007Tripathy et al, , 2009 in this field of research are also reviewed. In doing the review, emphasis is given to the work carried out in India and, consequently, a summary of important observations and conclusions drawn are indicated.…”

“…Every single radiation track may cause a mutation Measured data are shown as points with error bars. Calculated total (PEQ þ EQ) distributions using the HION code (Nandy et al, 1999) are shown as solid lines with PEQ component as dashed lines and EQ component as dotted lines. Fig.…”

Preequilibrium neutron emission in heavy ion reaction: Mean field effect and multiple emission

“…These models estimate the reaction dynamics through the time evolution of nucleons considering the nucleon-nucleon (N-N) interaction in the phase space volume. We had developed a semiclassical formalism [24,25] (henceforth termed the "HION" model) to describe energy-angle distribution of preequilibrium (PEQ) nucleon emission in heavy ion reaction in the projectile energy range of 10-30 MeV/u. In this model, energy and momentum of the scattered nucleon is determined from the kinematics of nucleon-nucleon scattering.…”

“…The phase space available to the excited nucleons at the onset of heavy ion fusion is determined from the overlap of Fermi momentum spheres of the two interacting nuclei. This model had certain shortcomings [24,25] in explaining the experimental double differential neutron multiplicities [26][27][28] in two respects. The model underestimated the experimental spectra for intermediate emission energies at the forward angle and overestimated the spectra at the backward angles.…”