A REVISED VERSION OF PRAL - THE PROJECTED RANGE ALGORITHM

PRAL, a projected range algorithm is widely used to predict the first few moments of the spatial distribution of ions implanted into amorphous targets of infinite extent. It is shown here that PRAL contains mathematical defects. These are corrected in the new Kent range algorithm (KRAL) which is shown to be compatible with LSS theory. KRAL and PRAL predict the same range but the new algorithm is superior in its predictions of lateral and longitudinal standard deviations when compared with moments derived from the Monte Carlo code TRIM using the same differential nuclear scattering cross sections and electronic energy loss mechanisms.