Germanium detector efficiency and identification of radioactive nuclides in the atmosphere

Sammanfattning

Radioactive elements are found everywhere on planet Earth, even in the air. In this project, the aim was to get a deeper understanding of the radioactive nuclides in the air. This was done by detecting gamma-rays from a filter, that had air flowing through it for a week, using a HPGe detector. Before these measurements were made, a foil of 232Th was placed in the detector to get a grasp of the decay chain and to better understand the efficiency of the detector. The efficiency of the detector was found to be lower than the efficiency that was simulated. In the air filter, nuclides from the decay chains of 232Th and 238U were observed. All the nuclides identified were below the step of radon inthe decay chains. The activity was then calculated and a theoretical decay fit, founded on the differential equations governing radioactive decay, was put upon the calculated values to be able to say something about the abundances of radioactive nuclides in the atmosphere. The decay fit was accurate for 238U’s decay chain but less so for 232Th’s when compared with experimental values. Future studies can continue the work on these differential equations to get a better understanding about the radionuclides in the atmosphere.