Coincidence methods in gamma-ray spectrometry for radioecological applications

• Main Author: Markovic, Nikola
• Format: Book
• Language: English
• Published: DTU Nutech 2018
• Subjects: /dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_being; SDG 3 - Good Health and Well-being; Arctic; Arctic Ocean
• Online Access: https://orbit.dtu.dk/en/publications/45410aa6-fa55-45f4-8eb2-330dea54efb9; https://backend.orbit.dtu.dk/ws/files/152969835/Nikola_Markovic_thesis_NM_30_11_2017.pdf

Gamma spectrometry is one of the most powerful radiometric techniques available. The nondestructive method enables both quantitative determination and identification of the majority of radioisotopes. Compared to other radiometric techniques, it has a great advantage in being able to detect minor isotopes, even in the presence of a large background from a multitude of other radioactive elements without any need for separating the isotopes. This has enabled the technique to be used as the standard tool in nearly all disciplines where radioisotopes are analyzed. The technique plays an important role in environmental radioactivity, nuclear safety and reactor monitoring, nuclear medicine, isotope geology… Gamma spectrometric analysis of artificial radioisotopes in man (whole body counting) has improved the understanding of human metabolism, while the analysis of the very same radioisotopes in sea water has shed light on Arctic Ocean water circulation. All of this is thanks to a deliberate and continuous effort to improve the technique over the years. With improvements in energy resolution, detector size and performance, coupled to better background reduction, studies of new phenomena in environmental radioactivity have become possible. Not seldom have these improvements occurred suddenly though discrete events. The introduction of digital signal processing in gamma spectrometry is definitely one such event, and it will, in the next coming years, revolutionize the way in which we acquire information through environmental gamma spectrometry. Up till now, gamma spectra were measured in a way that the energy deposited in a detector was measured with an analogue chain (preamplifier, amplifier, ADC), events were saved in computer memory with its energy and arranged into a histogram called spectrum. With digital list-mode systems each event is saved with its energy and time-stamp when the event happened. In simple words, the difference between the standard gamma spectrum and time-stamped list-mode file can be compared to a ...