Suren Kandasamy Dissertation.pdf - University of Surrey

M.Sc Dissertation3.5 Detection efficiencyFirst the apparatus was setup as shown in the Fig. 3.1 and then the 137 Cs sourcewas placed in front of the detector. After that total number of counts was noted within agiven acquiring time. Then the number of counts in a photopeak was takencorresponding to the energy. Then the previous step was repeated for 60 Co, 22 Na and152 Eu sources. Finally diameter of the detector and the distance between the source anddetector were taken.3.6 Self-counting of LaCl 3 :Ce detectorTo measure the internal natural radioactivity, the Lanthanum detector was placed intoa well shielded chamber (lead castle) for self-counting. The acquisition time was kept 2days, in order to get a good statistics. Finally the spectrum was collected.3.7 Time ResolutionH.VH.VBaF 2 DetectorBaF 2 DetectorAnodePMT60 CoPMTAnodeCFDStartTACStopFixedDelayCFDInputMCAFigure 3.2 Schematic diagram of the experimental set-up using the slow fasttechnique. The anode signals pass through the fast channel which consists ofConstant Fraction Discriminator (CFD) and time-to-amplitude converter (TAC).The arrows in the figure indicate the direction in which the signal travelled [4].The basic experimental setup was arranged as shown in Fig. 3.2. Two BaF 2scintillators are directly coupled with XP2020 photomultiplier and S563 voltagedivider. One voltage divider (BaF 2 detector connected with start signal) connected withCanberra model 3102D high voltage power supply (H.V) operated at - 2000 Volts. Andother one (BaF 2 detector connected with stop signal) connected with ORTEC 456 H.VK. Suren 15