MEASUREMENTS OF STAGE EFFICIENCY FUNCTIONS INCLUDING INTERSTAGE LOSSES FOR A SIERRA AND A BERNER IMPACTOR AND EVALUATION OF DATA BY A MODIFIED SIMPLEX-METHOD

High-volume cascade impactors of various designs are used extensively in air sampling to determine the size distribution of natural and artificial radioactive aerosols. In many cases it is not legitimate to neglect the interstage losses (wall losses). In this study the efficiency curves of all stages including interstage losses were measured for a Sierra and a Berner impactor. In addition to these actual measurement problems there are mathematical problems of interpreting impactor data. The simplex method according to Nelder and Mead (1965) is one method of evaluating impactor data. In this study the conventional simplex method was modified to find the correct physical solution with a higher probability of success, and to reduce computation time. These modifications are according to Spendley, Bremermann and Klinker. The capability of the computer program was tested with data of simulated size distributions. Refs.