Suren Kandasamy Dissertation.pdf - University of Surrey
Suren Kandasamy Dissertation.pdf - University of Surrey
Suren Kandasamy Dissertation.pdf - University of Surrey
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M.Sc <strong>Dissertation</strong>dNdHYY/2FWHMH 0HFigure 2.3 Representation <strong>of</strong> Gaussian shape peak with standard deviation , theFWHM is given by 2.35 [1].An ideal representation <strong>of</strong> the peak is shown in Fig. 2.3. A formal definition <strong>of</strong>detector energy resolution, R, is defined as:FWHMR 100%2.3H0The energy resolution R is thus a dimensionless fraction conventionally expressedas a percentage. Semiconductor diode detectors used in alpha spectroscopy can have anenergy resolution less than 1%, whereas scintillator detector used in gamma-rayspectroscopy normally show an energy resolution in the range 5-10% [1]. The value <strong>of</strong>detector resolution depends upon the size <strong>of</strong> detector and the energy <strong>of</strong> photons. Countsrates also affect the resolution and that‟s why it is better to use low rate sources forlonger time instead <strong>of</strong> using high rate sources. When using low rate source the signal tonoise ratio is better and the peak is closer to the Gaussian graph.2.4.3 Detection efficiencyDetection Efficiency describes the proportion <strong>of</strong> radiation events that recorded bya detector. It can include both geometric and radiation interaction effects. There arethree measurements <strong>of</strong> the efficiency <strong>of</strong> any detection system, Absolute totalefficiencyABS, Intrinsic efficiencyINT, and Intrinsic Peak efficiency P.K. <strong>Suren</strong> 9
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