Measurement of the 235U(n, f) cross section relative to the 6Li(n, t) and 10B(n, α) standards from thermal to 170 keV neutron energy range at n_TOF

Scientific paper - Original scientific paper

• Author: S. Amaducci
• Author: ...
• Author: Damir Bosnar; MBZ: 134936
• Author: ...
• Author: Petar Žugec; MBZ: 326085
• Collaboration: n_TOF Collaboration
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

The 235U(n, f) cross section was measured at n_TOF relative to 6Li(n, t) and 10B(n, α), with high resolution (L = 183.49(2)m) and in a wide energy range (25meV–170 keV) with 1.5% systematic uncertainty, making use of a stack of six samples and six silicon detectors placed in the neutron beam. This allowed us to make a direct comparison of the yields of the 235U(n, f) and of the two reference reactions under the same experimental conditions, and taking into account the forward/backward emission... More asymmetry. A hint of an anomaly in the 10–30 keV neutron energy range had been previously observed in other experiments, indicating a cross section systematically lower by several percent relative to major evaluations. The present results indicate that the cross section in the 9–18 keV neutron energy range is indeed overestimated by almost 5% in the recently released evaluated data files ENDF/B-VIII.0 and JEFF3.3, as a consequence of a 7% overestimate in a single GMA node in the IAEA reference file. Furthermore, these new high-resolution data confirm the existence of resonance-like structures in the keV neutron energy region. The results here reported may lead to a reduction of the uncertainty in the 1–100 keV neutron energy region. Finally, from the present data, a value of 249.7±1.4(stat)±0.94(syst) b·eV has been extracted for the cross section integral between 7.8 and 11 eV, confirming the value of 247.5±3 b·eV recently established as a standard. Less

• Keywords (english): n_TOF; 235U; fission cross section
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: European Physical Journal A: Hadrons and Nuclei
• Numbering: vol. 55, no. 7, 120
• p-ISSN: 1434-6001
• e-ISSN: 1434-601X
• DOI: https://doi.org/10.1140/epja/i2019-12802-7
• URN:NBN: urn:nbn:hr:217:490728
• Publication: 2019
• Project: Number: IP-2018-01-8570; Title (croatian): Elektroni, kaoni i neutroni u preciznim mjerenjima svojstava hadrona i jezgara; Acronym: EKNpEXP; Leader: Damir Bosnar; Jurisdiction: Croatia; Funding stream: IP
• Document URL: https://link.springer.com/article/10.1140/epja/i2019-12802-7
• Type of resource: Text
• Access conditions: Open access
• Public note: © The Author(s) 2019. This article is published with open access at Springerlink.com. This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Received: 21 March 2019. Revised: 30 May 2019. Published online: 26 July 2019.
• Created on: 2020-08-18 10:51:13