发表机构
IRFU, CEA, Université Paris-Saclay; Institut Laue-Langevin; CEA, DES, IRESNE, DER, Cadarache（法国原子能及替代能源委员会萨克雷大学核物理研究所; 朗之万研究所; 法国原子能及替代能源委员会卡达拉舍设施）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用ILL的FIPPS谱仪和有源靶，通过瞬发和延迟伽马射线测量235U(n_th,f)的同位素裂变产额，发现132Sn产额较JEFF-3.3低约7倍，归因于其基态产生；90Kr衰变存在约40%过剩，可能源于90Rb基态馈送高估。
AI 中文摘要
我们展示了在 ILL 使用 FIPPS $\gamma$ 射线谱仪，以溶解在液体闪烁体中的 $^{235}$U 制成的有源靶进行的测量活动的初步结果。利用瞬发 $\gamma$ 射线提取了绝对、独立的同位素裂变产额。我们获得了 $^{235}$U(n$_{\mathrm{th}}$,f) 反应中一组选定的产额较好的偶偶核的产额，并将其与 JEFF-3.3 评估数据进行了比较。其中包括双幻核 $^{132}$Sn，我们观察到其相对于 JEFF-3.3 存在显著亏损（约因子 7）。利用 FIFRELIN 裂变碎片退激代码，我们将这一差异解释为 $^{132}$Sn 主要在断裂时或中子蒸发后以其基态产生的证据。同一实验中记录的延迟 $\gamma$ 射线也进行了分析。与核数据库相比，$^{132}$Sn 的 $\beta$ 衰变未发现偏差。然而，在 $^{90}$Kr 的 $\beta$ 衰变中发现了约 40% 的过剩，这可能源于评估数据中 $^{90}$Rb 的基态馈送被高估。
英文摘要
We present preliminary results from a measurement campaign conducted with the FIPPS $γ$-ray spectrometer at the ILL using an active target made of $^{235}$U 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 $^{235}$U(n$_{\mathrm{th}}$,f) reaction and compared them with JEFF-3.3 evaluated data. This included the doubly magic nucleus $^{132}$Sn, 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 $^{132}$Sn 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 $^{132}$Sn compared to the nuclear database. However, an excess of about a 40% was found in the $β$ decay of $^{90}$Kr, which may originate from an overestimated ground-state feeding of $^{90}$Rb in the evaluated data.
