20.500.12556/RUL-173704 Primerjava izkoristkov visokoločljivih germanijevih (HPGe) detektorjev za spektrometrijo gama Comparison of Efficiencies of High Purity Germanium (HPGe) Detectors for Gamma Spectrometry V sklopu posodobitve smo Laboratorij za meritve radioaktivnosti nadgradili z novo metodo za določevanje izkoristka detektorjev. Izkoristek detektorja je ena od ključnih fizikalnih veličin, če želimo natančno ovrednostiti specifično aktivnost vzorcev. Metoda Efftran temelji na integraciji Monte Carlo in zahteva natančen model detektorja, vendar je hitrejša in izvedbeno cenejša od starejše, empirične metode. Moja naloga je bila validirati novo metodo z upoštevanjem rezultatov pridobljenih s staro. Ker metoda Efftran temelji na prenosu izkoristka detektorja za konfirmacijski vzorec na izbran vzorec, sem za meritve izvedel na treh vzorcih, ki se med seboj razlikujejo v pomembnih veličinah: vzorec vode, ki je podoben konfrmacijskemu vzorcu, aerosolni filter, ki ima drugačno geometrijo in vzorec jekla, ki ima drugačno matriko. Z izkoristki detektorja pridobljenimi z obema metodama, sem izračunal specifične aktivnosti radionuklidov v vzorcih in preveril ujemanje z referen£nimi vrednostmi. Rezultati z metodo Efftran se v okviru negotovosti večinoma ujemajo z referenčnimi vrednostmi, a sem hkrati ugotovil, da Efftran nepravilno izračuna koincidenčne popravke, v primerih ko pride do pojava koincidenc med izsevanimi žarki X in žarki γ radionuklida v vzorcu. Ta ugotovitev bo dodatno pomagala k izboljšavi metode. As part of the latest upgrade of the Laboratory for Radioactivity Measurements, a new method for determining detector efficiency has been introduced. Detector efficiency is one of the key parameters when performing measurements and analyses of samples, as it must be well understood in order to accurately calculate the specific activity of samples. The Efftran method is based on Monte-Carlo integration and requires an accurate detector model, but it is faster and comparatively cheaper than the older empirical method. My goal was to validate the new method using the results obtained with the old approach. Since the Efftran method relies on transferring the detector efficiency from a confirmational sample to the analyzed sample, I chose three samples for measurements that differ in their key parameters: a water sample, which is similar to the confirmational sample, an aerosol filter which has a different geometry, and a steel sample which has a a different matrix. Using the detector efficiencies obtained with both methods, I calculated the specific activities of radionuclides in the samples and compared them with the reference values. The results obtained with the Efftran method mostly agree within the limits of reported uncertainties with the reference values. However, I discovered, that Efftran incorrectly calculates true coincidence summing corrections that occur between emitted X-rays and γ-rays of a radionuclide in the sample. This finding is very relevant for further development of the method. Spektrometrija gama Efftran Monte Carlo integracija izkoristek detektorja specifična aktivnost. Gamma spectrometry Efftran Monte Carlo integration detector efficiency specific activity. true false false Slovenski jezik Angleški jezik Zaključna naloga 2025-09-20 08:15:24 2025-09-20 08:15:28 2025-10-11 03:43:08 0000-00-00 00:00:00 2025 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 154102 251453955 19439.pdf 19439.pdf 1 3B52045F1560CF6E93C84DE720D655BB 91a85230708a8b9c0ae7b95425bc5bd7bf0f5d1688b6fb60e893db53c6c289af 05e817f6-95e9-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=218354 Fakulteta za matematiko in fiziko 0 0 0