Investigation ofSource Detection Algorithms forGross Counting Portal Monitors

setting asingle alarm-threshold countrate, algorithms canbe Abstract- Inrecent years, heightened security concerns have usedto correct background levels, smoothrandom prompted increased interest inradiation portal monitors, fluctuations, anddetect small increases incount ratedueto instruments capable ofdetecting, andinsomecasesidentifying, weaksources.Thisworkfocuses onalgorithms forgamma- gamma-rayandneutron-emitting radioactive material passing through them.Alongwithefficient and reliable physical raymeasurement analysis usinggrosscounting portal detectors, suchmonitors needsoftware capable ofanalyzing the monitors, butsimilar methodsmay beapplicable inother resulting signals inorder toeffectively catch weakradioactive portal monitor measurements. sources. Thesoftware should beabletodistinguish between the sometimes subtle signals duetoweaksources andthevarying background. After investigating several possible source-detection II MATHEMATICAL METHODS algorithms, aprogramhasbeendeveloped tolocate signals from weakly radioactive sources inrealtime. Byincluding correctionsA DataSmoothing forbackground suppression duetotrucks shielding thedetector andchanging background levels, thisprogram iscapable of Thedataproduced byportal monitors usually consists ofa detecting significantly weaker sources thancurrent software. The setofgamma-ray counts, eachrecorded overasmall time limitations ofthis method will also bediscussed. interval and,insomecases, thereading fromanoccupancy sensor. Because thenumber ofcounts recorded perinterval is large, thedistribution ofcounts wellapproximates aGaussian I.*INTRODUCTION