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.