Lenain, C., Marqués, F. M., Gibelin, J. et al. (93 more authors) (2026) Direct observation of three-neutron emission from 7 He * and the search for the trineutron. Physical Review Research. L022003. ISSN: 2643-1564
Abstract
Three-neutron emission from He7 has been directly measured for the first time, following neutron knockout from a He8 beam at 156 MeV/nucleon. A resonancelike structure at 2.08(4) MeV above the He4+3n threshold [Ex=2.68(4) MeV] with a width of 3.9(2) MeV was observed and deduced to arise predominately from the predicted Jπ=3/22− 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 He*7 via the 21+ excited state of He6. 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 |
|---|---|
| Authors/Creators: |
|
| Copyright, Publisher and Additional Information: | © 2026 authors. |
| Keywords: | nucl-ex,nucl-th |
| Dates: |
|
| 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: | 06 May 2026 04:33 |
| Published Version: | https://doi.org/10.48550/arXiv.2603.10859 |
| Status: | Published |
| Refereed: | Yes |
| Identification Number: | 10.48550/arXiv.2603.10859 |
| Related URLs: | |
| Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:239212 |
Download
Filename: sr8h-2n6v.pdf
Description: Direct observation of three-neutron emission from 7 He∗ and the search for the trineutron
Licence: CC-BY 2.5

CORE (COnnecting REpositories)
CORE (COnnecting REpositories)