Resonance and Thermal-Neutron Total Cross Sections for Promethium-147 and Promethium-148m

Resonance parameters for ¹⁴⁷Pm and ^148mPm have been determined and the resonances ¹⁴⁷Pm have been analyzed up to 317 eV. Only one resonance was observed for ^148mPm; its location at 0.17 eV is important for thermal reactor calculations Transmission measurements were initially made on four samples of ¹⁴⁷Pm₂O₃ containing 1.6% of the decay product ¹⁴⁷Sm. Later measurements, made on a mixed sample of (^148mPm + ¹⁴⁷Pm)₂O³ and on ¹⁴⁷Sm, provided resonance parameters for ¹⁴⁷Pm and an opportunity for a complete reevaluation of the previous ¹⁴⁷Pm results. Corrections for the samarium content could also be made. Both shape and area analyses were performed. The measured total cross section for ¹⁴⁷Pm at 0.025 eV was 198 ± 8 b and a capture resonance integral of 2280 ± 200 b was calculated. Using the parameters of the ^148mPm resonance at 0.17 eV, a corresponding total thermal-neutron cross section of 10 600 b was ob-tained. Integral measurements with cadmium-covered samples gave a value of (3.6 ± 2.4) × 10³ b for the resonance integral of ^148mPm, thereby setting an upper limit of 6000 b.