Publications

mon in general gamma-spectrometry prac tice with semicon duc tor detec tors, where axially symmetrical sources prevail. However, in some particular applica tions, like radioactivity con - trol of food or construction materials (for monitoring and regulatory purposes, radiological emer gency pre pared ness, or in the af ter math of nu clear ac ci dents), brick shapes may come to significance. In or der to sim plify rou tine/re pet i tive low ac tiv ity mea sure ments, it is eas ier and more prac ti cal to mea sure the ra dio ac tiv ity of these sources as such, i. e., with out trans form - ing them into “reg u lar” (cylin drical or Marinelli) shapes. This saves con sid er ably on lab o ra - tory time, workforce and consumables – thus even tu ally cut ting the cost of anal y sis and im - proving laboratory performance. In addition, the accuracy of the analytical results is en hanced, as the pos si bil i ties for sys tem atic er rors are re duced. To that aim, in the pres ent work a mathemat ical model for brick-source efficiency calibration is developed. The well known, ac cu rate and widely used ef fi ciency trans fer prin ci ple is ap plied, to gether with de tec - tor ef fi ciency cal cu la tions based on the ef fec tive solid an gle W concept. For test ing pur poses, compar isons are made with previously developed and well estab lished mathemat ical models for detec tor calibration involv ing axially symmet rical sources (point, disc, and cylin der). Namely, brick sources were re garded as a sort of in ter po la tion be tween the outer and in ner cyl in der of the same height, for which ef fi cien cies could be ac cu rately de ter mined by nu mer i - cal cal cu la tions (soft ware AN GLE). For the sake of com plete ness, the equivoluminous cylin - ders were taken into ac count as well. Brick shape sources of var i ous sizes and pro por tions were ex am ined; when ap proach ing zero di men sions, re sults were ob tained for point and disc sources. All cal cu la tions were per formed in gamma en ergy range 50-3000 keV. The re sults are con sistent and logical, with no discrepan cies indicating bugs or systematic errors – thus con - vinc ingly con firming the fundamentality and re li abil ity of the model. The model is about to be in cor po rated into AN GLE soft ware as a new func tion al ity, so as to make it avail able to gamma spectrometry community.