Radsafers: I have recently placed on the Web the graphs of all photon interaction coefficients (photoelectric absorption, Compton scattering, etc.) for all elements. The URL is http://www1.usa1.com/~aic/2121.html Paul Kehler AIC SOFTWARE P.O. Box 544 Grafton, MA 01519 Tel: 508-839-6779 Fax: 508-839-4853