Neutron Capture Cross Sections of ¹⁸²W, ¹⁸³W, ¹⁸⁴W, and ¹⁸⁶W from 2.6 to 2000 keV

Pre-equilibrium reactions on the stable tungsten isotopes at low energy

“…Systematic correction factors F SR within the EDBW formula were obtained by using the experimental [58] average radiative widths Γ Moreover, the f E1 (E γ ) thus obtained have been checked within the calculations of capture cross sections of Hf, Ta, and W isotopes in the neutron energy range from keV to 2-3 MeV, by using in the nucleon energy range E above the respective binding energy B, for the target-nucleus ground-state spin I 0 , fitted in order to obtain the BSFG level-density parameter a and ground-state shift ∆ (corresponding to a spin cut-off factor calculated with a variable moment of inertia between the half and 75% of the rigid-body value, for the excitation energies from g.s. to the nucleon binding energy, and the reduced radius r 0 = 1.25 fm) if the estimation of the EDBW model correction factors is based on ORNL values [73] of the average radiative widths (actually, on their ratio to the s-wave nucleon resonance spacings, while for the latter we have used the above-mentioned RIPL-2 values). These values are compared in Table 5 with those corresponding to the capture data fit.…”

“…Comparison of experimental[58,73] average s-wave radiative widths Γ γ 0 (in meV) used for normalization of the γ -ray strength functions f E1 (E γ ), and values corresponding to fit of experimental neutron capture data of the W isotopes…”

Evaluation of stable tungsten isotopes in the resolved resonance region

“…The beam was collimated to a diameter of 45 mm at the sample position. 6 Li glass scintillators enriched at 95% in 6 Li were used as neutron detectors. Capture measurements were performed at 10 m in 50 and 800 Hz regime, and at 30 and 60 m at 800 Hz.…”

“…A good set of resonance parameters for W, used as starting values for the fitting procedure, has been obtained by combining results of the transmission measurement of Camarda et al [ 5] and the capture measurements of Macklin et al [ 6]. From transmission measurements the parameter gΓ n (proportional to the neutron width) values are deduced, whereas from capture measurements the capture kernel gΓ n Γ γ /(Γ n +Γ γ ) can be obtained.…”

“…From reference [ 6] we also considered the average radiation width for the four different isotopes. For the parity assignment of a resonance we applied the Bollinger-Thomas approach to the gΓ n values.…”