Preparation of solid water-equivalent radioactive standards.
The use of a superabsorbent polymer to prepare water-equivalent volume standards by solidification without the need of irradiation to effect the polymerization process, is described. Less than 40 g of the polymer is needed to solidify 1 litre of solution. Monte Carlo simulations of the gamma-ray escape probability indicate that the mixture is water-equivalent to better than 1.0%. During preparation, the solidified material can be mixed until homogeneity is achieved. Comparative measurements made before and after solidification confirmed the homogeneity and demonstrated water equivalence.
Radioactivity Standards Laboratory, CSIR-NML, 15 Lower Hope Road, Rosebank, Cape Town 7700, South Africa. fmorris@csir.co.za
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D000042:Absorption; D000180:Acrylic Resins / Q000737:chemistry*; D011829:Radiation Dosage; D011868:Radioisotopes / Q000032:analysis* / Q000592:standards*; D011874:Radiometry / Q000379:methods* / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods* / Q000592:standards*; D014867:Water / Q000737:chemistry*
D000180:Acrylic Resins; D011868:Radioisotopes; D014867:Water; C006903:carbopol 940