Fast inorganic scintillators in extreme ultra high vacuum applications

This report presents scintillator devices based on BaF/sub 2/ and YAP:Ce crystals for particle detection and beam monitoring of singly and highly charged ions in the CRYRING storage ring. The scintillator materials fulfil the requirement of the Extreme Ultra High Vacuum of the order of 10/sup -12/ mbar. Both crystals are known to be very fast responding scintillators. The BaF/sub 2/ crystal is mounted as a vacuum window with the PM-tube attached outside. This setup has been used for many years without any indication of deterioration, confirming the high radiation hardness of BaF/sub 2/. The device employing a YAP:Ce crystal is placed inside the vacuum tube, close to the circulating heavy ion beam. Methods have been developed for efficient transmission of the scintillation light to the PM-tube placed outside vacuum. The presented detector systems have been employed in measurements of atomic lifetimes, detection of 1 GeV Pb ions and heavy ion beams electron cooled to ordering.