Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum
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| Autori principali: | , , , , , , , , , , , , , , , , |
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| Natura: | Preprint |
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2024
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| author | Cannarozzo, Simone Pomp, Stephan Solders, Andreas Al-Adili, Ali Gao, Zhihao Lantz, Mattias Penttilä, Heikki Kankainen, Anu Moore, Iain Eronen, Tommi Ruotsalainen, Jouni Ge, Zhuang Jaries, Arthur Mougeot, Maxime Raggio, Andrea Virtanen, Ville Stryjczyk, Marek |
| author_facet | Cannarozzo, Simone Pomp, Stephan Solders, Andreas Al-Adili, Ali Gao, Zhihao Lantz, Mattias Penttilä, Heikki Kankainen, Anu Moore, Iain Eronen, Tommi Ruotsalainen, Jouni Ge, Zhuang Jaries, Arthur Mougeot, Maxime Raggio, Andrea Virtanen, Ville Stryjczyk, Marek |
| contents | The origin of the large angular momenta observed for fission fragments is still a question under discussion. To address this, we study isomeric yield ratios (IYR), i.e. the relative population of two or more long-lived metastable states with different spins, of fission products.
We report on IYR of 17 isotopes produced in the 28 MeV $α$-induced fission of $^{232}$Th at the IGISOL facility of the University of Jyväskylä. The fissioning nuclei in this reaction are $^{233,234,235}$U*. We compare our data to IYR from thermal neutron-induced fission of $^{233}$U and $^{235}$U, and we observe statistically significant larger IYR in the $^{232}$Th($α$,f) reaction, where the average compound nucleus (CN) spin is 7.5 $\hbar$, than in $^{233,235}$U(n$_{th}$,f), with average spins 2.5 and 3.5 $\hbar$, respectively.
To assess the influence of the excitation energy, we study literature data of IYR from photon-induced fission reactions, and find that the IYR are independent of the CN excitation energy. We conclude that the different IYR must be explained by the different CN spin alone. This implies that the FF angular momentum only partly comes from the fission process itself, and is in addition influenced by the angular momentum present in the CN. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_04340 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum Cannarozzo, Simone Pomp, Stephan Solders, Andreas Al-Adili, Ali Gao, Zhihao Lantz, Mattias Penttilä, Heikki Kankainen, Anu Moore, Iain Eronen, Tommi Ruotsalainen, Jouni Ge, Zhuang Jaries, Arthur Mougeot, Maxime Raggio, Andrea Virtanen, Ville Stryjczyk, Marek Nuclear Experiment Nuclear Theory The origin of the large angular momenta observed for fission fragments is still a question under discussion. To address this, we study isomeric yield ratios (IYR), i.e. the relative population of two or more long-lived metastable states with different spins, of fission products. We report on IYR of 17 isotopes produced in the 28 MeV $α$-induced fission of $^{232}$Th at the IGISOL facility of the University of Jyväskylä. The fissioning nuclei in this reaction are $^{233,234,235}$U*. We compare our data to IYR from thermal neutron-induced fission of $^{233}$U and $^{235}$U, and we observe statistically significant larger IYR in the $^{232}$Th($α$,f) reaction, where the average compound nucleus (CN) spin is 7.5 $\hbar$, than in $^{233,235}$U(n$_{th}$,f), with average spins 2.5 and 3.5 $\hbar$, respectively. To assess the influence of the excitation energy, we study literature data of IYR from photon-induced fission reactions, and find that the IYR are independent of the CN excitation energy. We conclude that the different IYR must be explained by the different CN spin alone. This implies that the FF angular momentum only partly comes from the fission process itself, and is in addition influenced by the angular momentum present in the CN. |
| title | Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum |
| topic | Nuclear Experiment Nuclear Theory |
| url | https://arxiv.org/abs/2412.04340 |