Results on 235U(nth,f) isotopic fission yields using prompt and delayed gamma rays at the FIPPS spectrometer of the ILL
Abstract
We present preliminary results from a measurement campaign conducted with the FIPPS γ-ray spectrometer at the ILL using an active target made of 235U dissolved in a liquid scintillator. Prompt γ rays were used to extract absolute, independent isotopic fission yields. We obtained yields for a selected set of well-produced even-even nuclei from the 235U(nth,f) reaction and compared them with JEFF-3.3 evaluated data. This included the doubly magic nucleus 132Sn, for which we observed a pronounced deficit (about a factor 7) with respect to JEFF-3.3. Using the FIFRELIN fission fragment de-excitation code, we interpreted this discrepancy as evidence that 132Sn is mainly produced in its ground state at scission or after neutron evaporation. Delayed γ rays recorded in the same experiment were also analysed. No deviation was found in the beta decay of 132Sn compared to the nuclear database. However, an excess of about a 40% was found in the β decay of 90Kr, which may originate from an overestimated ground-state feeding of 90Rb in the evaluated data.
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BibTeX
@misc{materna2026results,
title = {{Results on $^235$U(n$_\mathrmth$,f) isotopic fission yields using prompt and delayed gamma rays at the FIPPS spectrometer of the ILL}},
author = {T Materna and P Herran and M Ballu and Q Poirier and A Letourneau and D Doré and L Thulliez and C Michelagnoli and F Kandzia and Y.H Kim and U Köster and O Litaize and O Sérot and A Chebboubi},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.13033},
eprint = {2609.13033},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05771266v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Results on ^235U(n_th,f) isotopic fission yields using prompt and delayed gamma rays at the FIPPS spectrometer of the ILL
AU - T Materna
AU - P Herran
AU - M Ballu
AU - Q Poirier
AU - A Letourneau
AU - D Doré
AU - L Thulliez
AU - C Michelagnoli
AU - F Kandzia
AU - Y.H Kim
AU - U Köster
AU - O Litaize
AU - O Sérot
AU - A Chebboubi
PY - 2026
DA - 2026/09/11
PB - HAL
DO - 10.48550/arxiv.2609.13033
UR - https://hal.science/hal-05771266v1
AB - We present preliminary results from a measurement campaign conducted with the FIPPS γ-ray spectrometer at the ILL using an active target made of ^235U dissolved in a liquid scintillator. Prompt γ rays were used to extract absolute, independent isotopic fission yields. We obtained yields for a selected set of well-produced even-even nuclei from the ^235U(n_th,f) reaction and compared them with JEFF-3.3 evaluated data. This included the doubly magic nucleus ^132Sn, for which we observed a pronounced deficit (about a factor 7) with respect to JEFF-3.3. Using the FIFRELIN fission fragment de-excitation code, we interpreted this discrepancy as evidence that ^132Sn is mainly produced in its ground state at scission or after neutron evaporation. Delayed γ rays recorded in the same experiment were also analysed. No deviation was found in the beta decay of ^132Sn compared to the nuclear database. However, an excess of about a 40% was found in the β decay of ^90Kr, which may originate from an overestimated ground-state feeding of ^90Rb in the evaluated data.
ER -