Measurements of the 210gBi to 210mBi activation ratio for the 209Bi(n,γ) reaction with thermal and epithermal neutrons at the Soreq IRR1 reactor

Irradiations of bismuth samples with thermal and epi-thermal neutrons have been performed for a comparison of activation to the 210gBi ground state and to the 210mBi meta-stable state. The bismuth irradiations were conducted at the Soreq IRR1 research reactor at a core location with integrated neutron flux of approximately 2 x 1018 neutrons/cm2 and a gold cadmium ratio of ~3.1. Two nearly identical bismuth samples were irradiated, one without and one with a cadmium shield, to enable a comparison between thermal and epi-thermal neutron capture cross sections. Subsequent gamma spectrometry indicate nearly equal levels of activation to the ground and to the meta-stable states of 210Bi, both with thermal and epi-thermal neutrons. Absolute thermal cross sections and resonant integrals were deduced by including previously reported bismuth activation measurements performed conjointly with gold foil activation for normalization. A comparison of the present results with existing data is presented. It is argued that the bismuth resonances lie in the neutron energy range relevant for stellar temperatures, and therefore the neutron capture cross section ratio (σ_g/σ_m ) measured for the epi-thermal neutrons is relevant also for stellar 210Bi production. This is of importance since bismuth lies at the end of the chain for the s‐process reaction for nucleo‐synthesis in stars. Precise knowledge of bismuth activation to the 210mBi meta-stable state is also vital for planning of GEN-IV reactors given the 3 million year half-life of 210mBi.

SHOR A.;  WEISSMAN L.;  TESSLER M.;  AVIV O.;  EISEN Y.;  FEINBERG G.;  MISHNAYOT Y.;  PLOMPEN Arjan;  VAINTRAUB S.; 

2022-02-08

AMER PHYSICAL SOC

JRC126749

2469-9985 (online),   

https://journals.aps.org/prc/abstract/10.1103/PhysRevC.105.025802,    https://publications.jrc.ec.europa.eu/repository/handle/JRC126749,   

10.1103/PhysRevC.105.025802 (online),