THE STATISTICS OF BACKGROUND REJECTION IN DIRECT-DETECTION EXPERIMENTS FOR DARK-MATTER

A number of the new generation of dark matter direct detection experim ents, now underway, employ gamma-background rejection techniques to im prove their performance. Event discrimination permits the setting of l imits on dark matter event rates orders of magnitude below the raw bac kground event rates. However, proper attention must be paid to systema tic, as well as statistical errors, during data analysis. We illustrat e the importance of using detectors with good intrinsic discrimination if the impact of systematic errors is to be minimised.