The Neutron Capture Cross Section of the Tungsten Isotopes from 0.01 to 10 Electron Volts

Neutron capture cross-section measurements from 0.01 to 10 eV on ¹⁸²W, ¹⁸³W, ¹⁸⁴W, and ¹⁸⁶W employing a totally absorbing gamma-ray detector are described. The 2200 m/sec values of the neutron capture cross section (in barns) obtained are:  The shapes and magnitudes of the cross-section curves are compared to calculations using reported resonance parameters. Negative energy levels are postulated to account for the discrepancies between calculation and experiment for ¹⁸²W and ¹⁸⁴W. The ¹⁸²W parameters are: E₀ = −30.7 eV, Γγ= 57 meV, = 20 meV, g = 1, and for ¹⁹⁴W: E0 = −110 eV, Γγ= 57 meV, = 48.4 meV, g = 1. The ¹⁸³W and ¹⁸⁶W measured cross sections are lower than those calculated from reported positive-energy resonance parameters. A measurement of the gold-capture cross section was used as a check on the experimental techniques employed. This work was supported in part by the National Aeronaustics and Space Administration, Space Nuclear Propulsion Office, under Contract SNPC-27.