Scintillator studies with MeV charged particle beams

Thin scintillators used as detectors of escaping fusion products in the TFTR tokamak are studied with Van de Graaf beams of 3-MeV protons and 3.5-MeV alphas. ZnS scintillators are found generally adequate for the D–D experiments performed up to now, marginal for near-term D–T experiments because the emitted light saturates at alpha fluxes greater than 1010 cm−2 s−1, and totally inadequate for future ignited plasmas. Other scintillators have been tested that have lower light efficiencies but much better properties at high fluxes. In particular, the P46 scintillator appears to be an excellent choice for future experiments.