Candidate Resonant Tetraneutron State Populated by theHe4(He8

Abstract

A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction ^{4}He(^{8}He,^{8}Be) at 186 MeV/u. The energy of the state is 0.83±0.65(stat)±1.25(syst) MeV above the threshold of four-neutron decay with a significance level of 4.9σ. Utilizing the large positive Q value of the (^{8}He,^{8}Be) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently.

Ground-state properties ofH5from theHe6(d,Wuosmaa1, Bedoor2, Brown3 et al. 2017Phys. Rev. C13451View full textAdd to dashboardCite

“…In addition to the 6 He(p, 2p) 5 H reaction used by Korsheninnikov, Meister et al reported 3 H+2n correlations from proton-knockout data from 6 He on a 12 C target [24], and gave a resonance energy E R =2.5-3.0 MeV and width Γ=3-4 MeV, rather different from earlier results. Another proton-removal reaction that could be used to search for 5 H is 6 He(d, 3 He) 5 H. Some reports of this reaction [25][26][27] exist.…”

“…Suggestions of correlated "dineutron" emission have recently been reported [1][2][3]. Experimental reports supporting the observation of the tetra-neutron have also appeared [4,5]. Some theoretical analyses indicate that it should not be stable or quasi-stable [6,7], although a recent report of No Core Shell Model (NCSM) calculations for 4 n suggests the possibility of a broad, low-lying resonance [8].…”

“…In 2001 Korsheninnikov et al reported a peak in the missing-mass spectrum for the 6 He(p, 2p) 5 H reaction at E R =1.7±0.3 MeV, with a width of Γ = 1.9 ± 0.4…”

“…[9][10][11] and references therein). 5 H, as well as even heavier isotopes of hydrogen such as 6 H and 7 H [12][13][14][15], have been the focus of considerable recent scrutiny.…”

“…This small width conflicted with an R-matrix analysis [20] as well as with predictions from other theoretical analyses of 5 H (see below). Possible excited states [21], and a high-statistics correlation analysis of the 3 H+2n decay products of 5 H populated in that reaction [22] have also been described. A structure corresponding to a ground-state resonance is less prominent in missing-mass spectra presented in Refs.…”