A1 Journal article (refereed)
Compound-Nucleus and Doorway-State Decays of β-Delayed Neutron Emitters 51,52,53K (2024)

Xu, Z. Y., Grzywacz, R., Gottardo, A., Madurga, M., Alonso, I. M., Andreyev, A. N., Benzoni, G., Borge, M. J. G., Cap, T., Costache, C., De Witte, H., Dimitrov, B. I., Escher, J. E., Fijalkowska, A., Fraile, L. M., Franchoo, S., Fynbo, H. O. U., Gonsalves, B. C., Gross, C. J., . . . Yuan, C. X. (2024). Compound-Nucleus and Doorway-State Decays of β-Delayed Neutron Emitters 51,52,53K. Physical Review Letters, 133(4), Article 042501. https://doi.org/10.1103/PhysRevLett.133.042501

JYU authors or editors

Publication details

All authors or editors: Xu, Z. Y.; Grzywacz, R.; Gottardo, A.; Madurga, M.; Alonso, I. M.; Andreyev, A. N.; Benzoni, G.; Borge, M. J. G.; Cap, T.; Costache, C.; et al.

Journal or series: Physical Review Letters

ISSN: 0031-9007

eISSN: 1079-7114

Publication year: 2024

Publication date: 22/07/2024

Volume: 133

Issue number: 4

Article number: 042501

Publisher: American Physical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/PhysRevLett.133.042501

Publication open access: Openly available

Publication channel open access: Partially open access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/96472

Publication is parallel published: https://eprints.whiterose.ac.uk/215134/

Abstract

We investigated decays of 51,52,53K at the ISOLDE Decay Station at CERN in order to understand the mechanism of the 𝛽-delayed neutron-emission (𝛽⁢𝑛) process. The experiment quantified neutron and 𝛾-ray emission paths for each precursor. We used this information to test the hypothesis, first formulated by Bohr in 1939, that neutrons in the 𝛽⁢𝑛 process originate from the structureless “compound nucleus.” The data are consistent with this postulate for most of the observed decay paths. The agreement, however, is surprising because the compound-nucleus stage should not be achieved in the studied 𝛽 decay due to insufficient excitation energy and level densities in the neutron emitter. In the 53K 𝛽⁢𝑛 decay, we found a preferential population of the first excited state in 52Ca that contradicted Bohr’s hypothesis. The latter was interpreted as evidence for direct neutron emission sensitive to the structure of the neutron-unbound state. We propose that the observed nonstatistical neutron emission proceeds through the coupling with nearby doorway states that have large neutron-emission probabilities. The appearance of “compound-nucleus” decay is caused by the aggregated small contributions of multiple doorway states at higher excitation energy.

Keywords: nuclear physics; particle physics

Free keywords: nuclear physics; beta decay; level densities; neutron physics; nuclear decay; thermal & statistical models; neutron techniques; time-of-flight neutron spectroscopy

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Ministry reporting: Yes

VIRTA submission year: 2024

Preliminary JUFO rating: 3