High resolution alpha-particle-spectrometry for radium analysis-the effects of sample thickness and filter pore size

Abstract

In the α-particle spectrometric technique for radium isotope analysis, the effects of the barium carrier thickness and pore size of the membrane filter (used for the main BaRa sulphate filtration) on the resolution of the α-particle energy peaks were investigated. With 0.45 μm Millipore membrane filters, the full widht at half maximum (FWHM) for 4.78 MeV α-decay peak of 226Ra decreased from 221.7 to 121.3 keV with reduction in barium carrier additions from 320 to 20 μg Ba. The resolution further improved to 67.0 keV for 20 μg Ba carrier when 0.2 μm Nucleopore filters were used. There was also a significant decrease (20-50%) in the retention of radon and its daughters compared to their equilibrium concentrations as the barium carrier thickness was reduced. A correlation study between 133Ba tracer and 226Ra isotopes recovery factors gave a recovery factor 226Ra133Ba ratio of 0.93 ± 0.08 in the main BaRa sulphate precipitate under various pH and sulphate concentration conditions. © 1988.