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>supply <strong>of</strong> Hamamatsu R6231 PMTs is positive value <strong>of</strong> 1500 Volts. For this study thatoperating voltage is found positive value <strong>of</strong> 950 Volts. So this is good bias voltage <strong>of</strong>LaCl 3 :Ce(10%) with the size <strong>of</strong> 44.450.8mmscintillator detector coupled withHamamatsu R6231 PMTs. For this positive high voltage supply was kept for otherstudies with LaCl 3 :Ce(10%) detector.4.2 Select the optimum shaping timeTo get the optimum shaping time <strong>of</strong> ORTEC 672 amplifier with LaCl 3 :Ce(10%),the 137 Cs spectrum was collected with different shaping time such as 0.5 s, 1.0 s, 2.0s, 3.0 s, 6.0 s, 10.0 s. For each spectrum was acquired same time period as 600sec. Table 4.2 shows the calculated value <strong>of</strong> energy resolution % (FWHM) for 137 Cs fullenergy peak <strong>of</strong> each spectrum.Table 4.2 Resolution changes with shaping time for peak energy <strong>of</strong> 662 keV ( 137 Cs)Shapingtime(µs)FWHM(Channel)PeakChannelnumberResolution %0.5 56.50 1405.41 4.021.0 42.18 1139.70 3.702.0 25.57 692.29 3.693.0 18.15 480.87 3.776.0 10.45 257.00 4.0710.0 6.74 148.92 4.53Using the values shown in Table 4.2 the graph <strong>of</strong> resolution versus shaping timeplotted for LaCl 3 :Ce(10%) detector, as shown in Fig. 4.2.K. <strong>Suren</strong> 19
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