Measurement of keV-Neutron Capture Cross Sections and Capture Gamma-Ray Spectra of ¹⁶⁷ Er

Abstract

The neutron capture cross sections and capture γ-ray spectra of ¹⁶⁷Er were measured in the neutron energy region of 10 to 90keV and at 550 keV. Using a neutron time-of-flight method with a 1.5-ns pulsed neutron source by the ⁷Li(p, n)⁷Be reaction, the measurement was performed by detecting prompt γ rays from an enriched capture sample with a large anti-Compton Nal(Tl) spectrometer. A pulse-height weighting technique was applied to observed capture γ-ray pulse-height spectra to extract capture yields. The capture cross sections were derived with the error of about 5% by using the standard capture cross sections of ¹⁹⁷Au. The present results were compared with the evaluated values of ENDF/B-VI and the previous measurement. The present measurement at 550 keV was the first one. The capture γ-ray spectra were obtained by unfolding the observed capture γ-ray pulse-height spectra. An anomalous shoulder was clearly observed around 3 MeV in the γ-ray spectra and the energy position of the shoulder was consistent with the systematics obtained in our previous work. The multiplicities of the observed γ rays were derived from the γ-ray spectra.

KEYWORDS:

• neutrons
• keV range 10–100
• keV range 100–1000
• neutron capture
• cross sections
• gamma spectra
• experimental data
• erbium 167
• gold 197
• anti-Compton Nal(Tl) gamma spectrometers
• time-of-flight method
• pulse-height weighting technique
• gamma-ray multiplicity