Sequential and Simultaneous Emission of Particles Fromp+ Al Collisions at GeV Energies

The energy and angular dependence of double differential cross sections d(2)sigma/d Omega dE were measured for p, d, t, He-3,He-4,He-6, Li-6,Li-7,Li-8,Li-9, Be-7,Be-9,Be-10, and B-10,B-11 produced in collisions of 1.2, 1.9, and 2.5 GeV protons with an Al target. It was found that the cross sections are almost independent of the beam energy. The spectra and angular distributions indicate a presence of two contributions: a quasi-isotropic, low-energy one which is attributed to the emission of particles from excited remnants of the intranuclear cascade, and an anisotropic part which is interpreted to originate from the first stage of the reaction. The experimental data are compared with an intranuclear cascade model coupled to evaporation, and to statistical multifragmentation models using their standard parameter settings. It was found that all applied models produce very similar results describing spectra of the intermediate mass fragments. All models also reproduce well the low-energy part of the spectra of light charged particles (below approximate to 30 MeV). The description of the higher energy part (50-150 MeV) of the light charged particles spectra is poorer, deteriorating with decreasing scattering angle and decreasing mass of the particles.