Title of the program: MCSDA transport in thin films. It uses the continuous slowing down approximation (CSDA) suitably corrected to include energy Catalogue number: AALC straggling. Elastic and inelastic cross sections in the Born approximation, allowing analytical random sampling, are de-Program obtainable from: CPC Program Library, Queen's Uni-rived from a simple parameterization of the self-consistent versity of Belfast, N. Ireland (see application form in this atomic density. issue) Method of solution Computer: IBM 3083 XE; Installation: Centre d'informática, Random sampling of the various variables from the adopted Universitat de Barcelona cross sections is done analytièally by using the inversion and composition sampling methods. In this way, the storage Ic-Operat,ng system: VM/SP CMS quired is minimized and rounding errors are avoided. Programming language: FORTRAN IV Restrictions on the complexity of the problem High speed storage required: 127 Kbytes Large statistical uncertainties may be found in the simulation results of problems involving large initial energies and small Number of bits in a byte: 8 cutoff energies or very thick samples. Peripherals used: card reader, printer Typical running time Number of lines in program and test deck: 1265 The running time largely depends on the particular characteristics of each problem. On the ~BM 3083XE, the time needed to reduce the statistical uncertainties to about one per cent is in Keywords: electron transport, multiple scattering, Monte Carlo the order of 1000 s. method, random simulation, Born cross sections, continuous slowing down approximation (CSDA), straggling, electron transmission, electron backseattering Note This program also runs in a VAX 11/750 with VMS system Nature of physical problem with no changes. The running times are enlarged by a factor of The program does Monte Carlo simulation of kilovolt electron about 12.5. * Supported in part by the Comisiön Asesora de Investigacibn Cientifica y Técmca (Spain), contract no. 2157/83.