Performance of alpha particle spectroscopy using a Tastrak(TM) detector

Alpha particle spectroscopy by automated analysis of etched alpha particle tracks in TASTRAK(TM) (CR-39) type plastic is described. The method is based on the measurement of two geometric parameters of etched tracks, the minor axis (m), and the diameter of the etched out track end (d). Accurate measurement of these two parameters allows reliable separation of tracks according to alpha particle energy, with a FWHM of 105-130 keV, or 1.5-2.5%, in an energy band of 1.5 MeV. Pre-etching the plastic at 98 degrees C before exposure to the alpha particle source caused a decrease in V-T/V-B, resulting in an improved energy resolution of 80-110 keV (1.33-2%), with a concomitant decrease in the energy band to 1.2 MeV. Within this band, the intrinsic measurement efficiency is as high as 0.75, a critical factor for possible low level measurement applications. The results indicate that a basis exists for a robust working method for alpha particle spectroscopy in TASTRAK(TM) plastic.