Charge monitoring in an external proton beam

A number of problems are minimized for elemental analysis of material if the target is kept outside the vacuum. One problem with external analysis is the difficulty of accurately measuring the charge incident on the target. Four methods of monitoring charge were investigated. It was found that the charge collected from the target and exit foil and the gamma-ray counts and backscattered proton counts from the exit foil were proportional to the charge incident on the target, and were stable to changes in current and in time