Low temperature bolometers in RBS analysis

Recent results with bolometers as high resolution photon detectors raise hope of greatly improved energy resolution in the detection of α-particles and other light ions. A resolution of some hundred eV, which should be reachable from the theoretical point of view, would offer an improvement of the depth and mass resolution in RBS analysis. For this purpose we tested silicon bolometers with and without a copper absorber at a heat sink temperature of 300 mK. The particles detected by the bolometer were backscattered from a Ta-Cr-Si sample (at 1 K) irradiated by 200 keV light ions (H, He, B). An energy resolution of 8.7 keV FWHM for He ions was the best we achieved and is to our knowledge the best absolute value of energy resolution for α-particles measured bolometrically. This resolution is a factor of 3.5 worse than we expect from the measured signal-to-noise ratio. These discrepancies and future plans to improve performance will be discussed. (author). 13 refs.; 4 figs.; 2 tabs