| Title: |
Measurement of the α-ratio and (n,γ) cross section of U-235 from 0.2 to 200 eV at n_TOF |
| Authors: |
Balibrea-Correa, J.; Mendoza, E.; Cano-Ott, D.; the n_TOF Collaboration |
| Publication Year: |
2025 |
| Collection: |
Repositorio Institucional del CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas) |
| Description: |
We measured the neutron capture-to-fission cross-section ratio (alpha-ratio) and the capture cross section of U-235 between 0.2 and 200 eV at the n_TOF facility at CERN. The simultaneous measurement of neutron-induced capture and fission rates was performed by means of the n_TOF BaF2 Total Absorption Calorimeter (TAC), used for detection of γ-rays, in combination with a set of micromegas detectors used as fission tagging detectors. The energy dependence of the capture cross section was obtained with help of the Li-6(n,t) standard reaction determining the n_TOF neutron fluence; the well-known integral of the U-235(n,f) cross section between 7.8 and 11 eV was then used for its absolute normalization. The alpha-ratio, obtained with slightly higher statistical fluctuations, was determined directly, without need for any reference cross section. To perform the analysis of this measurement we developed a new methodology to correct the experimentally observed effect that the probabilities of detecting a fission reaction in the TAC and the micromegas detectors are not independent. The results of this work have been used in a new evaluation of U-235 performed within the scope of the Collaborative International Evaluated Library Organisation (CIELO) Project, and are consistent with the ENDF/B-VIII.0 and JEFF-3.3 capture cross sections below 4 eV and above 100 eV. However, the measured capture cross section is on average 10% larger between 4 and 100 eV. |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/pdf |
| Language: |
English |
| Relation: |
https://hdl.handle.net/20.500.14855/4541 |
| Availability: |
https://hdl.handle.net/20.500.14855/4541 |
| Rights: |
open access |
| Accession Number: |
edsbas.66DC0C16 |
| Database: |
BASE |