Yields of activation products in 226ra irradiation in the high-flux sm reactor

A target containing 3.16 mg of 226RaCO 3 was irradiated in the neutron trap of the SM reactor for 25 effective days at a thermal neutron flux of 1.5 × 10 15 cm- 2 s- 1. After the irradiation and storage for 17 days, the irradiated material was dissolved and the Ra activation products were chemically isolated. The yields of 229Th, 230Th, 227Ac, and 228Th were determined by α- and γ-ray spectroscopy and by mass spectrometry. Formation of significant amounts of 228Ra, not predicted by the calculations, was revealed. It was suggested that the short-lived isotope 227Ra has a high neutron capture cross section [seff( 227Ra) ̃ 1.5 × 10 3 b]. © Pleiades Publishing, Inc., 2012.