This invention provides a high energy radiation system which produces UV radiation comprising a selectively attenuating material which increases the ratio of desired to undesired radiation to reduce the radiation damage to a target by selectively attenuating at least 30 percent of the radiation from greater than 200 up to 240 nm which impinges upon said attenuating material, and directs greater than 50 percent of the radiation from 240 nm to 280 nm which impinges upon said attenuating material.