Energy Straggling of Heavy Charged Particles in Thick Absorbers

Department 0,( Physics, Berea College, Berea, Kentucky 40403 t;,.. (Received 29 August 1968; revised manuscript received 23 January 1969) " , j The theory of energ}. straggling attempts to calculate F(E,S), where F(E,S)dli is the fraction of the heavy i charged particles which have an energy bet\veen II: and I:'+dl:: after a path length S has been traversed in 1 absorbing medium. This paper develops a method of calculating FIE,sJ for path lengths large enough so ~ that F(/::,S) is alm~t Ga~ssian. The m~thod rema!ns vali~ until a large fr~ction of the l!articles run o~t of energy. The theory 1S applied to calculations of F(E,S) for ;,O-MeV protons m Be and for ;'.3-MeV a part1cles in air. The calculations for a particles in air are in good agreement \vith the experimental results of Rotondi and Gieger. The theo~. is also in agreement with numberical calculations by Tschalar.