Measurements of Capture Gamma Rays from the Broad 27-, 49-, and 97-keV Neutron Resonances and the Narrow 44-keV Neutron Resonance of ¹⁹F

Abstract

The capture γ rays from the 27-, 44-, 49-, and 97-keV neutron resonances of ¹⁹F were measured using an anti-Compton HPGe γ-ray spectrometer. A neutron time-of-flight method was adopted with a 1.5-ns pulsed neutron source by the ⁷Li(p, n)⁷ Be reaction. The standard capture cross sections of ¹⁹⁷ Au and a pulse-height weighting technique were employed to determine the number of neutrons incident on a capture sample. The numbers of observed primary γ-ray transitions were 17, 6, 10, and 7 for the 27-, 44-, 49-, and 97-keV resonances, respectively. The partial radiative widths corresponding to those transitions were derived for the broad 27-, 49-, and 97-keV resonances, and the partial capture kernels for the narrow 44-keV resonance. The total radiative width or total capture kernel was derived by summing up the partial radiative widths or partial capture kernels of each resonance. Previous measurements and evaluations were compared with the present results. Moreover, the branching ratios of the 4,315-, 4,731-, and 4,898-keV states of ²⁰F were firstly derived.

KEYWORDS:

• ke V range 10–100
• neutrons
• resonance reaction
• radiative width
• capture kernel
• branching ratio
• fluorine 19
• fluorine 20
• gold 197
• anti-Compton HPGe gamma-ray spectrometer
• time-of-flight method
• pulse-height weighting technique
• experimental data
• evaluations