1 2 A Referring to the biological effects of radiation compare and contrast the

1 2 a referring to the biological effects of

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2. (A) Referring to the biological effects of radiation, compare and contrast the dose response characteristics of the stochastic and deterministic effects. (10 marks) (B) Describe the mechanism by which the energy of ionising radiation is transferred to the fluor, and also discuss the problem of quenching in liquid scintillation counting. (10 marks) 3. In an experiment to determine the activity of 137 Cs in tea, the caesium is extracted by adsorption onto a bed of resin and is then counted in a well-type Nal (TI) spectrometer. Another bed of resin without caesium ions is used as the control. The following data are observed Counting rate observed in tea sample in 5 min = 517 cpm Counting rate observed in control in 5 min = 170 cpm i. Determine the suitable counting period for achieving a 0.01 fractional standard deviation for the net sample count rate. Also, determine the optimum counting period for the control. Suppose you obtain a total count for the sample and control of 3.80 x 10 4 and 6.25 x 10 3 respectively after counting them in the intervals determined in (i) above. Given the overall counting efficiency of the spectrometer be 16%
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  • Fall '17
  • R
  • Neutron, Ionizing radiation, University of Hong Kong, Scintillation counter

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