The probability of athermal divacancy formation has been calculated analytically with the help of the hard sphere approximation for several f. c . c . and b. c . c. metals /l/. Obtained data agree well with the results of computer simulation of low energy cascades (E 5 1 keV). Here the ratio of divacancies t o isolated vacancies is about 1/2. However, for high energy cascades (E > 1 0 keV) the analytical calculations of the production probability give reduced values (by 3 to 4 times) compared to computer simulation.This discrepancy is caused b y the fact that the hard sphere approximation is not effective for a high energy projectile. Thus for the Born-Mayer potentialwhere r is the distance between atoms, A, a are constants being equal t o 22.5 keV and 2 . 0~1 0-l1 m, respectively, in the c a s e of copper /2/; the collision diameter b = a ln(ZA/E), is of the s a m e o r d e r of magnitude as the interatomic distance. If E = 1 0 keV, b is approximately by an o r d e r of magnitude less for high energies. The hard sphere approximation does not take into account such processes where a projectile is moving between two neighbouring atoms of a crystal lattice at distances of r > b and knocking out both of them by i t s own field. This collision t y p e is a many-body one in nature.The three-body collision takes place i f the impact parameters q1 and 9 2 between crystal lattice atoms 1 and 2 and a projectile are less than the dis-

No abstract

No abstract

In this contribution the Monte Carlo method is used to compute the distributions of vacancies with depth in silicon irradiated by relativistic electron beams. The model of N-body interactions in a collision cascade that advances in isotropic continuum was incorporated into the Monte Carlo scheme of successive collisions to obtain depth distributions of vacancies, interstitial atoms, and vacancy clusters produced by 1 -I 0 MeV electrons in silicon. The model developed permits to obtain the statistically averaged space distributions of defects and thennal spikes. Besides the model explains the yield of clusters during sputtering. Defects formed by 3-electrons and primary knock-in atoms are also taken into account.

No abstract