MEASUREMENT OF BACKSCATTERING PARAMETERS WITH A PULSED ELECTRON-BEAM

Bunches of 1 MeV electrons were made to fall normally on surfaces of g raphite, aluminium, copper, silicon and silver and in each case the yi eld of backscattered electrons was measured using a special type of Fa raday cup. The average beam current was kept low enough to avoid any s urface heating and also to match the radiation levels that exist in so me regions of space. The measured values of backscattering ratios and coefficients are found to be close to the values derived using an empi rical relation but slightly higher than those reported earlier for rel atively high beam currents.