Direct observation of three-neutron emission from 7He*  and the search for the trineutron

S.W. Huang; C. Lenain; Zi Hao Yang; F.M. Marqués; J. Gibelin; J. G. Li; A. Matta; Nasser Kalantar-Nayestanaki; C. A. Douma; Muhsin Harakeh; et al.

doi:10.1103/sr8h-2n6v

Direct observation of three-neutron emission from ⁷He^* and the search for the trineutron

S.W. Huang
, C. Lenain
, Zi Hao Yang
, F.M. Marqués
, J. Gibelin
, J. G. Li
, A. Matta
, Nasser Kalantar-Nayestanaki
, C. A. Douma
, Muhsin Harakeh
, et al.

Nuclear Energy

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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 resonancelike structure at 2.08(4) MeV above the 4 He +3⁢𝑛 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=3/2−2 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.

Original language	English
Article number	L022003
Number of pages	9
Journal	Physical Review Research
Volume	8
Issue number	2
DOIs	https://doi.org/10.1103/sr8h-2n6v
Publication status	Published - Apr-2026

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@article{2017b266935d42cea07d74da9bd95f84,

title = "Direct observation of three-neutron emission from 7He* and the search for the trineutron",

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 resonancelike structure at 2.08(4) MeV above the 4 He +3⁢𝑛 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=3/2−2 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.",

author = "S.W. Huang and C. Lenain and Yang, \{Zi Hao\} and F.M. Marqu{\'e}s and J. Gibelin and Li, \{J. G.\} and A. Matta and Nasser Kalantar-Nayestanaki and Douma, \{C. A.\} and Muhsin Harakeh and \{et al.\}",

year = "2026",

month = apr,

doi = "10.1103/sr8h-2n6v",

language = "English",

volume = "8",

journal = "Physical Review Research",

issn = "2643-1564",

publisher = "American Physical Society",

number = "2",

}

TY - JOUR

T1 - Direct observation of three-neutron emission from 7He* and the search for the trineutron

AU - Huang, S.W.

AU - Lenain, C.

AU - Yang, Zi Hao

AU - Marqués, F.M.

AU - Gibelin, J.

AU - Li, J. G.

AU - Matta, A.

AU - Kalantar-Nayestanaki, Nasser

AU - Douma, C. A.

AU - Harakeh, Muhsin

AU - et al.

PY - 2026/4

Y1 - 2026/4

N2 - 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 resonancelike structure at 2.08(4) MeV above the 4 He +3⁢𝑛 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=3/2−2 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.

AB - 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 resonancelike structure at 2.08(4) MeV above the 4 He +3⁢𝑛 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=3/2−2 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.

U2 - 10.1103/sr8h-2n6v

DO - 10.1103/sr8h-2n6v

M3 - Article

SN - 2643-1564

VL - 8

JO - Physical Review Research

JF - Physical Review Research

IS - 2

M1 - L022003

ER -

Direct observation of three-neutron emission from 7He* and the search for the trineutron

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Direct observation of three-neutron emission from ⁷He^* and the search for the trineutron