Tests of a New Secondary Emission Chamber at the AGS

A secondary emission chamber (SEC) has been built using .00025¿ aluminum foils with a 200Ã… vacuum-deposited silver coating. After baking the assembly, the foils were cleaned with an argon glow discharge. The chamber was then installed in a primary proton beam at the Brookhaven AGS. A difference in sensitivity of 6% was noted between the chamber´s two emitter foils. After exposure to a flux of 1018-1019 protons/cm2, the sensitivity of one of the foils was found to have increased by 0.2% and the other to have decreased by 1.2%. This is substantially better than earlier designs.