²⁴¹Am Neutron Capture Cross Section Measurement using the NaI(Tl) spectrometer of the ANNRI beamline of J-PARC

ABSTRACT

The neutron capture cross-section of ²⁴¹Am was measured from 10 meV to about 500 keV using the NaI(Tl) spectrometer of the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) beamline in the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The total energy detection principle was applied in conjunction with the pulse-height weighting technique to derive the neutron capture yield. The present cross-section results were normalized using a ¹⁹⁷Au sample measurement by applying the saturated resonance method. The thermal cross section was measured to be 708 ± 22 b, in agreement with the evaluation in JENDL-5 of 709 b within uncertainties. In the keV region, the evaluated libraries of JENDL-5, ENDF/B-VIII.0 and JEFF-3.3 are in good agreement with the present results over 10 keV but show values lower by 30% to 70% below that energy. Moreover, the results of a resonance shape analysis of the resolved resonance region are also provided in the present paper.

KEYWORDS:

• ANNRI
• ²⁴¹Am
• neutron capture cross section
• J-PARC
• MLF
• minor actinide
• neutron time-of-flight
• resonance analysis
• thermal cross section

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The neutron experiments at the MLF of the J-PARC were performed under the user program [Proposal 2021P0301 and 2021B0313].