Suren Kandasamy Dissertation.pdf - University of Surrey

More documents

Recommendations

Info

M.Sc DissertationChapter 4Result and discussionPerformance and the characterization of the gamma ray detection properties ofBrilLanCe B350 (LaCl 3 :Ce(10%)) with the size of 44.450.8mmscintillatordetector was studied. This study involved selection of operating voltage, optimumshaping time, recording spectrum, energy resolution, detection efficiency, photofractionand time resolution.4.1 Select the supply voltage of the LaCl 3 :Ce(10%)The energy spectrum of 137 Cs was collected using LaCl 3 :Ce(10%) detectordirectly coupled with Hamamatsu R6231 PMT and ORTEC 672 shaping amplifier, fordifferent positive supply voltages. The amplifier coarse gain was set to be 20. Table 4.1shows the total number of net count recorded from MCA maestro for windows softwarefor each spectrum.Table 4.1 Net count changes with supply voltageSupply Voltage(+V)Total number ofnet CountError in netcounts±860 96997 230880 101885 215900 128618 357920 262350 433940 282660 477960 283665 543980 286255 6181000 287726 4751020 290150 5571040 289232 4131060 289122 3251080 286799 6101100 287589 7251120 289420 4371140 287418 2651160 288120 3101180 285417 5471200 283274 526K. Suren 17
Total number of net countsM.Sc DissertationFigure 4.1 shows the graph of total number of net counts versus supply voltage.This graph was plotted using the values shown in Table 4.1 for LaCl 3 :Ce(10%)detector.29000024000019000014000090000850 900 950 1000 1050 1100 1150 1200 1250Supply voltage(V)Figure 4.1 The counting curve of LaCl 3 :Ce(10%) detector as a function ofsupply voltage.The operating voltage was chosen by the high voltage corresponding to the centrepoints on the plateaus [6]. According to the Fig. 4.1 for the LaCl 3 :Ce(10%) detector theoperating voltage has been found as 950 Volts. When using PMTs for scintillatordetectors, there is a trade between dynamic range, linearity (proportionality of response)and resolution. This can discussed as follows. The very high photon yields of thescintillator could with its fast emission time means that standard PMTs can easilysaturate when operated at nominal anode to cathode biases of ~ 1000 V purely due totheir very high gains [10]. This can result in gross non linearities being into spectra.Reducing the PMT bias may reduce these non linearities and extend the dynamic range,but at the expense of a deteriorated energy resolution. Therefore, a trade is requiredbetween range, linearity and resolution [10].From the Fig. 4.1 shows below 860 Volts less number of counts was recorded.From that point the recorded count was suddenly increased. That means the PMTworking active voltage bias region. The maximum recommended high voltage powerK. Suren 18
Page 1 and 2: Characterisation of novel detector:
Page 3 and 4: M.Sc DissertationTable of ContentsC
Page 5 and 6: M.Sc DissertationAbstractDelft and
Page 7 and 8: M.Sc DissertationThe most commonly
Page 9 and 10: M.Sc DissertationGas-filled Detecto
Page 11 and 12: M.Sc Dissertation(A)(B)Figure 2.1 S
Page 13 and 14: M.Sc DissertationA desirable featur
Page 15 and 16: M.Sc DissertationAbsolute total eff
Page 17 and 18: Counts per channelM.Sc Dissertation
Page 19 and 20: M.Sc Dissertation3.2 To get the opt
Page 21: M.Sc Dissertationoperated at - 1800
Page 25 and 26: Energy Resolution (%)M.Sc Dissertat
Page 27 and 28: Number of countsM.Sc DissertationFr
Page 29 and 30: Number of counts128.78 keV244.70 ke
Page 31 and 32: M.Sc Dissertationenergies (approxim
Page 33 and 34: Photo-fraction %M.Sc Dissertation4.
Page 35 and 36: M.Sc DissertationFigure 4.10 shows
Page 38 and 39: M.Sc DissertationChapter 5Conclusio
Page 40 and 41: M.Sc Dissertation[10] Alan Owens, A
Page 42 and 43: M.Sc DissertationAppendix BDetector
Page 44 and 45: M.Sc DissertationAppendix CDecay ch
Page 46: No of CountsNumber of counts1274.5

Suren Kandasamy Dissertation.pdf - University of Surrey

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?