title: Determination of the depth of localized radioactive contamination by 137Cs and 60Co in sand with principal component analysis.
abstract: A method to determine the depth of buried localized radioactive contamination nonintrusively and nondestructively using principal component analysis is described. The γ-ray spectra from two radionuclides, cesium-137 and cobalt-60, have been analyzed to derive the two principal components that change most significantly as a result of varying the depth of the sources in a bespoke sand-filled phantom. The relationship between depth (d) and the angle (θ) between the first two principal component coefficients has been derived for both cases, viz. d(Φ) = x + y log(e) Φ where x and y are constants dependent on the shielding material and the γ-ray energy spectrum of the radioactivity in question, and φ is a function of θ. The technique enables the depth of a localized radioactive source to be determined nonintrusively in the range 5 to 50 mm with an accuracy of ±1 mm.
authors.affiliation: Engineering Department, Lancaster University , Lancaster LA1 4YR, UK. jcadams@univ.bangor.ac.uk
authors.forename: Jamie C
authors.initials: JC
authors.lastname: Adams
authors.forename: Matthew
authors.initials: M
authors.lastname: Mellor
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Joyce
mesh_terms: D002586:Cesium / Q000032:analysis*; D002588:Cesium Radioisotopes; D003035:Cobalt / Q000032:analysis*; D003037:Cobalt Radioisotopes; D005720:Gamma Rays; D017785:Photons; D025341:Principal Component Analysis; D012822:Silicon Dioxide / Q000737:chemistry*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D013057:Spectrum Analysis
chemical_list: D002588:Cesium Radioisotopes; D003037:Cobalt Radioisotopes; D012990:Soil Pollutants, Radioactive; D002586:Cesium; D003035:Cobalt; D012822:Silicon Dioxide