Measurement of Neutron Capture Cross Section of ¹⁶²Dy Between 0.003 eV and 10 keV using Total Energy Absorption Detector

Abstract

The neutron capture cross section of ¹⁶²Dy has been measured in the energy region from 0.003 eV to 10 keV by using the neutron time-of-flight (TOF) method with a 46 MeV electron linear accelerator (linac) at the Research Reactor Institute, Kyoto University (KURRI). To obtain the absolute capture cross section, an assembly of twelve pieces of Bi₄Ge₃O₁₂ (BGO) scintillators (each size: 5 cm x 5 cm, 7.5 cm long) was placed at a distance of 12.7±0.02 m from the neutron source and was employed as a total energy absorption detector for the prompt capture gamma-ray measurement. The enriched sample of ¹⁶²Dy (¹⁵⁶Dy : < 0.01 %, ^{, 58}Dy : < 0.01 %, ¹⁶⁰Dy : 0.08 %, ¹⁶¹Dy : 1.24 %, ¹⁶²Dy : 96.17 %, ¹⁶³Dy : 1.79 %, ¹⁶⁴Dy : 0.72 %) has a form of metallic plate (15 mm in diameter and 0.225 mm in thickness). A natural boron sample (18 mm x 18 mm, 1.10 g/cm²) was employed to monitor the neutron flux and spectrum of the TOF beam using the standard reference cross section of the ¹⁰B(n, α) reaction. The ¹⁶²Dy or ¹⁰B capture sample was set at the center of the through hole in the BGO assembly.

The current measurement has been carried out with uncertainties of 2.9 to 59.8 % in the relevant energy region. The experimental data measured by Danelyan et al. are in good agreement with the current measurement from 0.02 eV to 1 eV. The data by Kononov et al. are close to this measurement, although one can observe the tendency that the measurement is a little higher than those by Bokhovko et al. above several tens of keV. The evaluated data in ENDF/B-VI are in general agreement with the current measurement. The measurement has supplied the first data that has not been measured before in the energy range of 1 eV to 0.2 keV.

Keywords:

• capture cross section
• ¹⁶²Dy
• neutron time-of-flight
• measurement
• 0.003 eV to 10 keV energy range
• BGO scintillators
• total energy absorption detector
• ¹⁰B(n, α) standard cross section