Comparison of Energy Resolution of Different Gamma Ray Detectors

Abstract

This master thesis aims to find suitability of gamma ray detectors for gamma rays in different energy regimes. For this purpose three gamma ray detectors: high purity germanium detector (HPGe), sodium iodide with thallium as an activator (NaI:Tl) and lanthanum bromide with cerium as an activator (LaBr3:Ce3) were studied. To identify the unknown radioisotopes or to know the excited states of the nucleus, we study their energy spectrum. For this purpose, there exist various kinds of the detectors according to the energy range of interest. The energy spectrum is calibrated with the known gamma rays to have the correct identification of the peaks. According to statistical theory, the shape of peaks is generally gaussian, so the spectrum is fitted with gaussian function to known Full Width at Half Maximum (FWHM) of every fitted peak. FWHM and energy of incident radiation are directly proportional to one another. The small value of FWHM corresponds to small peak width value showing less statistical fluctuations. Energy Resolution depends on FWHM. The detectors with better resolution can distinguish peaks more appropriately.