THE EGS5 CODE SYSTEM

One of these six cross sections is selected by the user by specifying a PEGS5 input parameter. EIIis treated as being a part of Møller scattering in the EGS5 code, and neither the electron mean-freepath nor the stopping power are modified by including EII.After a K-shell vacancy creation by EII, the emission of a K x-ray is sampled using the K-shell fluorescence yield. This is identical to the calculation after a K-shell vacancy creation by thephotoelectric effect, although no Auger electron or cascade particle is followed in the treatment ofEII. For the case of K x-ray emission, the K x-ray energy is sampled from the ten K x-ray energieslisted in [57] according to the relative yield of the K x-ray, and the difference between E B (K shellbinding energy) and the K x-ray energy is deposited locally. In the case that no K x-ray is generated(i.e., Auger electron emission), E B is deposited locally.1.4.3 Other ImprovementsMerging of EGS and PEGSHistorically, EGS, the simulation code, and PEGS, the data generation code, were completelyseparate entities. This left open the possibility that a simulation could work on inappropriatedata, despite the built-in integrity checks. IN EGS5, the two codes have been merged, and nowEGS calls PEGS during its initialization procedures. Since the elastic scattering runtime databasescan require large amounts of CPU time in certain cases, the capability to reuse PEGS data filesstill exists, but its use is discouraged unless the accurate low energy elastic scattering option isemployed.Long sequence random number generatorsEGS5 employs the RANLUX random number generator[82], with the default “luxury level” set toone. RANLUX has a period of 10 155 unique random numbers and at luxury level 1 has a fidelityapproximately equal to that of RANMAR[81], which became the default random number generator forEGS4 in the interim period between major releases. The user may override the default luxury leveland so employ sequences which pass more stringent tests of randomness, although at a significantcost in speed.19