A HIGH-SENSITIVITY METHOD FOR HYDROGEN ANALYSIS IN THIN TARGETS

A sensitive and fast method for hydrogen analysis has been developed. The method is based on a technique where a proton beam of a few MeV im pinges on the target and the elastically scattered proton and the reco iling target hydrogen nucleus are detected in coincidence. The method makes use of the difference in time of flight and requires no energy d etermination. The system consists of two thin, large-area plastic scin tillation detectors placed at angles of 45-degrees relative to the bea m direction on either side of the beam. Evaluations of the system show ed that a stable coincidence yield with respect to position in the tar get plane and target displacement can be obtained provided that the ge ometry of the setup is carefully designed. The yield as a function of target thickness was almost linear for target thicknesses up to 2000 m ug/cm2. It was also found that count rates up to 500000 s-1 in each br anch may be used. The minimum detection limit for the hydrogen detecti on system was found to be of the order of a few pg/cm2 for a proton be am energy of 3.6 MeV.