Search

This work presents a new technique for discriminating between alpha particles of different energy levels. In a first study, two groups of alpha particles emitted from radium-226 and americium-241 sources were successfully separated using a CR-39 microfilm of appropriate thickness. This thickness was adjusted by chemical etching before and after irradiation so that lower-energy particles were stopped within the detector, while higher-energy particles were revealed on the back side of the detector. The number of tracks on the front side of the microfilm represented all alpha particles incident on that side from the two sources. However, the number of tracks on the back side of the microfilm represented only the long-range alpha particles of higher energy that arrived at that side. Therefore, by subtracting the number of tracks on the back side from the number of tracks on the front side, one could easily determine the number of tracks for the short-range alpha particles of lower energy that remained embedded in the microfilm. Discrimination of the two energy levels is thus achieved in a simple, fast, and reliable process.

Abstract: The thickness of a CR-39 detector is determined using an energy dispersive X-ray fluorescence (EDXRF) method of analysis. The method is based on exciting a suitable target and measuring the intensity of its fluorescence X-ray lines passing through the CR-39 sample in a fixed geometry. By properly selecting the target material, the method succeeds in assessing the thickness change of CR-39 detectors etched for different time intervals. The bulk etch rate (V b) may thus be obtained, which is an important parameter for any solid state nuclear track detector. Application of the EDXRF method yielded a value of V b =(2.01±0.04) μmh−1 for etching in a 6N NaOH solution at 75°C. This value agrees with the bulk etch rate of (1.90±0.03) μmh−1, obtained by the conventional mass-change method. [Copyright &y& Elsevier]

Monolithic CdZnTe detectors are promising for medical and small animal imaging thanks to their good energy resolution that allows both multidrug diagnostics and scatter rejection. Using the ULYSSE simulator, electrode geometry and detector thickness are optimized to improve detection efficiency and energy resolution for various material transport properties. As an example, for a 5 mm thick detector with (mutau)e=3times10-3 cm2/V, a 1.8 mm electrode pitch gives the best-simulated energy resolution on the conventional spectrum at 122 keV. Once the electrode geometry and thickness are optimized, electronic correction methods are shown to further reduce spectrum tailing. Corrections using cathode and anode signals have been tested with the high pressure Bridgman method (HPBM) CdZnTe and THM CdTe:Cl detectors. The best method for electronic correction appears to depend on the material [ABSTRACT FROM PUBLISHER]