THE IEC METHOD AND CONVERSION COEFFICIENTS OF THE 605-keV TRANSITION IN 134Ba

Abstract

Tests of the internal–external method of measuring conversion coefficients in the Vanderbilt double-focusing spectrometer have been made in search of possible errors arising from scattering of photoelectrons in the converter for a photon energy of 605 keV. This scattering may affect the factor, f, which corrects for the anisotropic distribution of the photoelectrons. The 605-keV transition in 134Ba populated by the beta decay of 134Cs was used. An accurate determination of the K, L, and M conversion coefficients of the 2+ to 0+, 605-keV, E2 transition in 134Ba was made. Three uranium converters 1.12, 2.19, and 3.71 mg/cm2 thick were used. The results are compared with the new theoretical calculations of f which depend on the converter thickness and consequently consider the effect of scattering. For photons of energy 605 keV or greater, the IEC method used in the Vanderbilt double-focusing spectrometers is insensitive (< 5%) to scattering in uranium converters < 4 mg/cm2 thick. The K, L, and M conversion coefficients were determined to be (5.03 ± 0.20) × 10−3, (7.07 ± 0.50) × 10−4, and (1.64 ± 0.18) × 10−4, respectively. The respective theoretical values of Rose are 5.08 × 10−3, 6.92 × 10−4, and 2.77 × 10−4. Sliv and Band give a value of 5.10 × 10−3 for the K conversion coefficient.