An irradiation chamber for experimental studies on SSNTD response to alpha particles

An irradiation apparatus was designed in our laboratory to study the detection efficiency dependence of SSNTDs (CR-39, LR115, Makrofol) on alpha particles of different energy and incident angle. The system was designed to irradiate up to nine detectors in a short time, allowing to obtain reproducible conditions on many detectors and therefore to reduce random variations of the results. The system is composed of a pressure-controlled stainless-steel chamber containing a 241Am source and a circular rotating table with 10 detector holders, one of which is devoted to an ion-implanted silicon detector for irradiation energy monitoring. The table rotation is controlled electronically via a photodiode-based system, so that the position of the detectors under the source is known with a maximum uncertainty of 0.5 mm. The detector holders allow to change the detector (both passive and active) to source inclination angle continuously and with an uncertainty better than 1∘. The source-to-detector distance is controlled electronically and can be varied from 5 to 30 cm with an uncertainty of about 0.1 mm. Some simulations, obtained using the transport code TRIM, to project the irradiation chamber and its main characteristics are reported and discussed.