On the detection of low-energy 4He, 12C, 14N, 16O ions in PC foils and its use in nuclear reaction measurements

Abstract

It is shown that by using a proper etching reagent the registration sensitivity of polycarbonate foils can be enhanced and they prove to be very suitable track recorders for alpha-particles emitted from nuclear reactions. At 6 MeV an energy resolution of 0.2 MeV can be achieved when using the track diameters as a measure of the particle energy. A theoretical way to calculate the track parameters important in nuclear reaction measurements involving alpha-particles recorded in polycarbonate foils is given. For this purpose the track etch rate vs residual range curve was determined by a parameter optimization procedure. The energy resolution of the track-diameter method as a function of the particle energy was predicted. In our earlier studies the track-diameter method was mostly used in angular distribution measurements of (d,α) nuclear reactions. In this work it is shown that with polycarbonate foils it can be well applied to excitation function measurements, as well. Such studies are presented for the α 0 and α 1 groups of the 27Al(p,α) 24Mg reaction in an energy interval between 1540 and 1920 keV. Finally, preliminary results on the track etching properties of low-energy O +, N +, C + and He + ions accelerated with a 5MV Van de Graaff generator are given.