By the very nature of secondary beams, their intensity is limited, particularly for beams of the highest interest - farthest away from stability. Active targets, which can be described as time projection chamber (TPC)-like detectors in which the detector gas is the target, have been shown to have the highest sensitivity for quantitative high resolution studies of rare events. The physics cases that can be addressed with these devices are reviewed and some of the first results obtained with first generation active targets are detailed. Finally some general ideas on the next generation of active targets are presented.
Drift velocity measurement in gas electron multiplier detectors for application in a time projection chamber polarimeter