Lenain, C., Marqués, F. M., Gibelin, J. et al. (93 more authors) (Accepted: 2026) Direct observation of three-neutron emission from $^7$He$^*$ and the search for the trineutron. Physical Review Research. ISSN: 2643-1564 (In Press)
Abstract
Three-neutron emission from $^7$He has been directly measured for the first time, following neutron knockout from a $^8$He beam at 156 MeV/nucleon. A resonance-like structure at $2.08(4)$ MeV above the $^4$He+$3n$ threshold [$E_x=2.68(4)$ MeV] with a width of $3.9(2)$ MeV was observed and deduced to arise predominately from the predicted $J^π=3/2^{-}_2$ level. The three-neutron invariant-mass spectrum was reconstructed and found to peak at around 1 MeV and could, through complete simulations incorporating neutron-neutron correlations, be very well described by the sequential decay of $^7$He$^*$ via the $2_1^+$ excited state of $^6$He. No evidence was found for any significant three-neutron correlations beyond those expected from well-established two-body interactions, including a trineutron resonance.
Metadata
| Item Type: | Article |
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| Authors/Creators: |
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| Copyright, Publisher and Additional Information: | This is an author-produced version of the published paper. Uploaded in accordance with the University’s Research Publications and Open Access policy. |
| Keywords: | nucl-ex,nucl-th |
| Dates: |
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| Institution: | The University of York |
| Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) |
| Date Deposited: | 18 Mar 2026 10:10 |
| Last Modified: | 18 Mar 2026 10:10 |
| Published Version: | https://doi.org/10.48550/arXiv.2603.10859 |
| Status: | In Press |
| Refereed: | Yes |
| Identification Number: | 10.48550/arXiv.2603.10859 |
| Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:239212 |

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