DETECTION OF FUSION ALPHAS FROM D(2)-T(2) GAS TARGETS

Detectors for recording alphas from fusions in D2-T2 gas targets requi re protection against diffusion of tritium into the detector medium. T ests have been carried out on surface barrier detectors to determine t he feasibility of using thin coatings of oxide and metal for this purp ose. The results show that a layer of 0.5 mum aluminium oxide plus 0.2 mum gold provides effective protection for at least 280 h, without im pairing the transmission of 2 MeV alphas into the detector. Tests of a n alternative detector, a phoswich of thin film plastic and lithium-gl ass scintillators, are also described.