20.500.12556/DKUM-58497 Detektiranje izotopov cezija 137 in kalija 40 v suhih gobah, suhih bananah, brazilskih oreščkih in prsti s spektrometrijo žarkov gama Detection of the isotopes cesium-137 and potassium-40 in dry mushrooms, dried bananas, brazil nuts and in the soil with gamma-ray spectrometry V diplomskem delu smo ugotavljali prisotnost izotopov cezija 137 in kalija 40 v različnih vzorcih. Za vzorce smo uporabili suhe gobe, suhe banane, brazilske oreščke in prst. Prisotnost radioaktivnih izotopov smo ugotavljali z metodo spektrometrije žarkov gama. S to metodo se določa radioaktivne izotope, ki sevajo žarke gama, v poljubnih snoveh. Deluje na podlagi merjenja energij emitiranih fotonov pri razpadu jeder radioaktivnih izotopov. Osrednji del diplome je eksperiment, ki je potreben za določitev aktivnosti radioaktivnih izotopov v posameznem vzorcu. Pri eksperimentu smo uporabljali strojno in programsko opremo podjetja Leybold. Meritve smo opravljali v dveh korakih. Najprej smo z referenčno meritvijo kalibrirali merilni sistem. Potem smo merili energijske spektre emitiranih fotonov pri radioaktivnih razpadih v posameznem vzorcu. Izvedli smo še meritev spektra energij fotonov iz okolja. Ker sevanje iz okolja vpliva na rezultate meritev šibkih sevalcev, smo meritve okolja odšteli od meritev vzorcev. Pri vseh meritvah smo uporabili svinčeni ščit, da smo dodatno zmanjšali vpliv okolice na meritve. Opravili smo analizo na podlagi primerjave izmerjenih spektrov izbranih vzorcev z referenčnimi vzorci, katerih vsebnost izotopov in aktivnost smo poznali. Na ta način smo lahko določili absolutne aktivnosti in relativne aktivnosti, izražene na maso vzorca gob, brazilskih oreščkov, suhih banan in prsti. Splošna ugotovitev naših meritev je, da so izmerjene meritve aktivnosti omenjenih živil zelo majhne in da ne odstopajo od povprečnih aktivnosti naše prehrane. In the diploma thesis we examined the presence of isotopes caesium-137 and potassium-40 in various samples. Our samples were dry mushrooms, dry bananas, Brazil nuts and soil. The presence of radioactive isotopes was determined with the method of gamma ray spectrometry. This method is used to determine radioactive isotopes, which radiate gamma rays, in optional substances. The method operates on the basis of measuring the energy of emitted photons during the decay of radioactive isotopes. The central part of the thesis is an experiment, which was necessary for determining the activity of radioactive isotopes in an individual sample. The experiment was conducted with the hardware and software of the company Leybold. The measurements were taken in two steps. First we conducted a baseline measurement to calibrate the measuring system. Then we measured the energy spectra of emitted photons in radioactive decay in an individual sample. Afterwards we conducted a measurement of energy spectra of photons from the environment. Because the radiation from the environment (so called background radiation) affects the results of measurements of weaker emitters, we have subtracted the background measurements from those of the samples. All measurements were conducted using a lead shield to additionally decrease the impact of the environment on the measurements. We also conducted an analysis based on the comparison of measured spectra of selected samples with the referential samples, the isotope content and activity of which we knew. That is how we were able to determine the absolute activities and relative activities, expressed on the mass of the sample of mushrooms, Brazil nuts, dry bananas and soil. The general conclusion of the measurements is that measured activities of mentioned foodstuffs are very small and do not deviate from the average activities of our food. radioaktivnost spektrometrija žarki gama scintilacijski detektor uran cezij kalij gobe radioactivity spectrometry gamma rays scintillation detector uranium caesium potassium mushrooms true true false [K. Hari] Slovenski jezik Angleški jezik Diplomsko delo 2016-04-20 17:18:16 2016-06-01 13:21:04 2022-06-17 03:06:14 2019-07-11 10:41:44 2016 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 539.16:54.027(043.2) 22236168 URN:SI:UM:DK:WQXBGD4E UN_Hari_Kristjan_2016.pdf UN_Hari_Kristjan_2016.pdf 1 4B624CB8DF308DAC1FB0FEC0897D24BB db3988b9e99b608f92ce1995a03ed59ef2e6c81cbf07ab204c5915b2ccc16cfe 151aed40-7c0c-11eb-bb7a-00155d0001ca https://dk.um.si/Dokument.php?lang=slv&id=89140 Fakulteta za naravoslovje in matematiko 0 0 0