(14 marks) ii. Explain the meanings of the following symbols in non-specific labelling U, G and n. (6 marks) (C) Write five general guidelines for the storage of radiochemicals. (10 marks)
RADIOISOTOPE UNIT: Sc87102 p. 10 5. (A) Describe separately the principles of tracer balance (total count) and tracer- rate (dilution) methods in flow-rate measurements. Indicate the various practical difficulties which may be associated with each method. (40 marks) (B) A sample of Or977 g solid CaS0 4 .2H 2 0 was added to 20 mL of 45 Ca labelled CaS0 4 saturated sol~tion. Assuming that the change of count-rate in the solution is entirely due to the isotopic exchange reaction of Ca+ 2 ions between the solution and the solid surface, determine the specific surface area (cm 2 g- 1 ) of the solid. Initial count-rate ofthe solution- 651 c.p.s. mL- 1 Final count-rate of the solution- 40S c.p.s. mL- 1 ca+ 2 concentration in the saturated solution - 1. 72 x l0- 2 M The effective cross-sectional area of ca+ 2 ion Avoga~ro' s number - 6. 02 x 10 2 ~ mole -l (20 marks) 6 .. Write concise notes on each of the followirtg: (A) the particle size and matrix effects in X-ray fluorescence analysis; (15 marks) (B) the merits and applications of beta and neutron radiography; (15 marks) (C) the applicabilities of beta particles in the transmission type radiogauging; and (15 marks) (D) the principles of operation of the ionisation smoke detector. (15 marks)
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- Fall '17
- Ionizing radiation