The energy and angular dependence of double differential cross sections d 2 σ/dΩdE were measured for p, d, t, 3,4 He, 6,7 Li, 7,9 Be, and 10,11 B produced in collisions of 0.175 GeV protons with Ni target. The analysis of measured differential cross sections allowed to extract total production cross sections for ejectiles listed above. The shape of the spectra and angular distributions indicate the presence of other nonequilibrium processes besides the emission of nucleons from the intranuclear cascade, and besides the evaporation of various particles from remnants of intranuclear cascade. These nonequilibrium processes consist of coalescence of nucleons into light charged particles during the intranuclear cascade, of the fireball emission which contributes to the cross sections of protons and deuterons, and of the break-up of the target nucleus which leads to the emission of intermediate mass fragments. All such processes were found earlier at beam energies 1.2, 1.9, and 2.5 GeV for Ni as well as for Au targets, however, significant differences in properties of these processes at high and low beam energy are observed in the present study.

The energy and angular dependence of double differential cross sections d 2 σ/d dE were measured for p, d, t, 3,4,6 He,6,7,8 Li,7,9,10 Be, 10,11 B, and C produced in collisions of 1.2, 1.9, and 2.5 GeV protons with a Ni target. The shape of the spectra and angular distributions almost does not change whereas the absolute value of the cross sections increases by a factor ∼1.7 for all ejectiles in this beam energy range. It was found that energy and angular dependencies of the cross sections cannot be reproduced by microscopic models of intranuclear cascade including coalescence of nucleons coupled to statistical model for evaporation of particles from excited, equilibrated residual nuclei. The inclusion of nonequilibrium processes, described by a phenomenological model of the emission from fast and hot moving sources, resulting from break up of the target nucleus, leads to very good reproduction of data. Cross sections of these processes are quite large, exhausting approximately half of the total production cross sections. Due to good reproduction of energy and angular dependencies of d 2 σ/d dE it was possible to determine total production cross sections for all studied ejectiles. Results obtained in this work point to the analogous reaction mechanism for proton induced reactions on Ni target as that observed previously for Au target in the same beam energy range.

The energy and angular dependence of double differential cross sections d 2 σ/dΩdE was measured for p, d, t, 3,4,6 He, 6,7,8,9 Li,7,9,10 Be, and 10,11,12 B produced in collisions of 1.2 and 1.9 GeV protons with Au target. The beam energy dependence of these data supplemented by the cross sections from previous experiment at 2.5 GeV is very smooth. The shape of the spectra and angular distributions almost does not change in the beam energy range from 1.2 to 2.5 GeV, however, the absolute value of the cross sections increases for all ejectiles. The phenomenological model of two emitting, moving sources, with parameters smoothly varying with energy, reproduces very well spectra and angular distributions of intermediate mass fragments. The double differential cross sections for light charged particles were analyzed in the frame of the microscopic model of intranuclear cascade with coalescence of nucleons and statistical model for evaporation of particles from excited residual nuclei. However, energy and angular dependencies of data agree satisfactorily neither with predictions of microscopic intranuclear cascade calculations for protons, nor with coalescence calculations for other light charged particles. Phenomenological inclusion of another reaction mechanism -emission of light charged particles from a "fireball", i.e., fast and hot moving source -combined with the microscopic model calculations of intranuclear cascade, coalescence and evaporation of particles leads to very good description of the data. It was found that the nonequilibrium processes are very important for production of light charged particles. They exhaust 40 -80% of the total cross sections -depending on the emitted particles. Coalescence and "fireball" emission give comparable contributions to the cross sections with exception of 3 He data where coalescence clearly dominates. The ratio of sum of all nonequilibrium processes to those proceeding through stage of statistical equilibrium does almost not change in the beam energy range from 1.2 GeV to 2.5 GeV for all light charged particles.

The energy and angular dependence of double differential cross sections d 2 σ/dΩdE were measured for p, d, t, 3,4,6 He,6,7,8 Li,7,9,10 Be, and 10,11,12 B produced in collisions of 1.2, 1.9, and 2.5 GeV protons with an Al target. The spectra and angular distributions of Li, Be, and B isotopes indicate a presence of two contributions: an isotropic, low energy one which is attributed to the evaporation of particles from excited remnants of the intranuclear cascade, and an anisotropic part which is interpreted to be due to multifragmentation of the remnants. It was found that such a hypothesis leads to a very good description of spectra and angular distributions of all intermediate mass fragments ( 6 He -12 B) using the critical value of the excitation energy per nucleon as a single parameter, varying slowly with the beam energy.