Evidence for the First Excited State of 
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Bezbakh, A. A.; Chudoba, V.; Krupko, S. A.; Belogurov, S.; Biaré, D.; Фомичев, А. С.; Gazeeva, E. M.; Gorshkov, A. V.; Grigorenko, L. V.; Kamiński, G.; Kiselev, O.; Kostyleva, D.; Kozlov, M. Yu.; Mauyey, B.; Mukha, I.; Nikolskii, E. Yu.; Piątek, Wojciech; Quynh, A. M.; Schetinin, V.; Serikov, A.; Sidorchuk, S. I.; Sharov, P. G.; Slepnev, R. S.; Stepantsov, S. V.; Świercz, Andrzej; Szymkiewicz, P.; Ter‐Akopian, G. M.; Wolski, R.; Zalewski, B.; Zhukov, M. V.

doi:10.1103/physrevlett.124.022502

Cited by 16 publications

(27 citation statements)

References 18 publications

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“…Compared to previous experiments, our measured mass and width are in good agreement with the 0.57 +0.42 −0.21 and 0.09 +0.94 −0.06 MeV reported in [25]. The value estimated in [26], 1.8±0.5, is larger but not too dissimilar from our result while ref. [27] reports the largest value at 2.2±0.5 MeV.…”

Section: Resonance Mass and Half-lifesupporting

confidence: 91%

“…[37] estimates a cross-section below 0.02 mb/sr in 9 • -21 • in c.m., while ref. [26] reports 0.025 mb/sr between 17 • and 27 • , and in ref. [27] even seems to increase beyond 0.04 mb/sr for angles below 10 • in c.m.…”

Section: Angular Distribution and Structurementioning

confidence: 94%

“…Meanwhile, its main characteristics, even its existence, are yet to be precisely determined. The first evidence was found in p( 8 He, 7 H)pp knock-out reactions [24]: a sharp increase in the energy distribution of the beam-like product just above the 3 H+4n mass was interpreted as hint of the formation of 7 H. Later, other indications were reported with 2 H( 8 He, 7 H) 3 He reactions: A candidate resonance was found between 1 and 3 MeV above the 3 H+4n mass [36], while a recent campaign suggests a 7 H ground state somewhere around 2 MeV and a width below 300 keV and, interestingly, possible excited states at ∼6 MeV [26,27]. Other experiments using the same reaction channel show less conclusive evidences [37,38].…”

Section: H Bymentioning

confidence: 98%

“…Evidences of excited states of 7 H around 6 MeV were also reported in refs. [26,27]. In the case of the 19 F channel, these states may be hidden in the tail of the peak associated with the 7 H ground state, although a fit to a tentative state around 6 MeV gives no statistically significant population above 0.1 mb/sr.…”

Section: Resonance Mass and Half-lifementioning

confidence: 99%

“…This is particularly feasible for light nuclei, where the binding limits and large neutron-to-proton ratios can be reached by adding few nucleons to stable isotopes. In hydrogen, experiments have already obtained evidences of 4,5,6,7 H isotopes, a chain of four resonances beyond the neutron dripline [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]. These systems are found to decay by neutron emission and thus believed to be built on a core of 3 H surrounded by neutrons confined by a centrifugal barrier and grouped in pairs.…”

Section: Introductionmentioning

confidence: 99%

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Ground-state properties of super-heavy hydrogen-7

Caamaño

Roger

Moro

et al. 2020

Preprint

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The properties of nuclei with extreme neutron–to–proton ratios, far from those naturally occurring on Earth, are key to understand nuclear forces and how nucleons hold together to form nuclei. 7H, with six neutrons and a single proton, is the nuclear system with the most unbalanced neutron–to–proton ratio known so far. However, its sheer existence and properties are still a challenge for experimental efforts and theoretical models. Here we report the formation of 7H as a resonance, detected with independent observables, and the first measurement of the structure and basic characteristics of its ground state. It is found that 7H is arranged as a 3H core surrounded by an extended four-neutron halo, with a unique four-neutron decay and a relatively long half-life thanks to neutron pairing. These properties are a prime example of new phenomena occurring in the most pure-neutron nuclear matter we can access in the laboratory.

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Section: Resonance Mass and Half-lifesupporting

confidence: 91%

Section: Angular Distribution and Structurementioning

confidence: 94%