Analyzing Simulated Data for an HPGe gamma-ray detector using the Kolmogorov-Smirnov Test (2008)

Undergraduate: Emily Morgan

Faculty Advisor: Reyco Henning
Department: Physics & Astronomy

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This study evaluates the accuracy of the Kolmogorov-Smirnov (KS) Test in determining radioactive source locations and type with high-purity Germanium (HPGe) detectors. The KS calculates the level of agreement between two distributions. GEANT 4 simulations of an HPGe detector were used to create energy histograms in ROOT and compared using the KS Test. The KS Test’s ability to determine a source’s contribution to a background spectrum was evaluated by running simulations of cobalt-60 (60Co) and thallium-208 sources. The energy spectrums were added together and tested against other histograms with varying contributions from each source. The KS Tests correctly determined the relative contributions of each source that made up the original, composite energy spectrum to within at least 10%. In position testing, 60Co was placed at various locations around the detector. The KS Test accurately showed that the decays from the same position produce the same energy histogram returning a value of 1, and the spectrum created 100 mm away was in fact different, returning a value of 0. Further tests will determine the minimum position interval KS begins to differentiate energy spectra. It could help identify the source of background radiation’s location and quantity in HPGe detectors used in the proposed Majorana experiment that will search for neutrinoless double-beta decay.