POLYCARBONATE TRACK ETCHED DETECTORS FOR QUALITATIVE ALPHA-SPECTROSCOPY IN RADON ENVIRONMENTS

Using the optimised two-step ECE technique, various alpha energy windo ws may be generated which vary in widths from 0.8 MeV to 7 MeV and the lowest detectable alpha energy may be shifted from 0.5 MeV to 8 MeV. By shifting alpha energy windows of minimum width over the energy rang e, qualitative alpha spectra of radon and radon daughters have been in vestigated using bare detectors and detectors inside the Karlsruhe rad on diffusion chamber. These spectra have been found to differ from tho se of the semiconductor detector mainly due to the critical angle of a lpha detection in Makrofol DE. The actual alpha energy windows for var ious etching regimes applied for the FZK radon diffusion chamber in di fferent laboratories are compared with that of a new optimised one usi ng a window of 4.5 MeV. This results in a factor of 3 higher radon res ponse and a smaller coefficient of variation. In addition, an alpha en ergy window has been optimised for a bare PC detector which allows for the measurement of Po-214 in air by discriminating the plateout effec ts on the detector surface.