RELATIVE CONTRIBUTION OF VARIOUS FACTORS TO THE FORMATION OF THE ENERGY-SPECTRUM OF FAST, MEDIUM-ENERGY, CHARGED-PARTICLES AND IONS TRANSMITTED THROUGH A THIN TARGET WITH FLUCTUATIONS OF THE TARGET THICKNESS

The characteristics of the energy spectra of kiloelectron-volt protons transmitted through a freestanding foil are investigated theoreticall y and experimentally as functions of the angle of incidence of the bea m on the target. Analytical expressions for the average characteristic s of the transmitted-particle energy spectrum are determined for the c ase of small-angle scattering. The combined influence of various facto rs affecting the formation of the energy spectra is taken into account : systematic stopping of particles in the medium, fluctuations of the particle energy losses in inelastic collisions, bending of the particl e trajectories due to multiple elastic scattering, and fluctuations of the target thickness. It is shown that the contributions of these fac tors to the width of the transmitted-particle energy spectrum depend d ifferently on the angle of incidence of the beam on the target surface . On the basis of this differentiation it is inferred from the experim ental dependence of the width of the energy spectra of kiloelectron-vo lt protons transmitted through a free-standing foil on the angle of in cidence of the beam that fluctuations of the particle energy losses in inelastic collisions are the predominant factor in the formation of t he proton energy spectra. (C) 1997 American Institute of Physics. [S10 63-7842(97)01305-6].