Search for resonances in 4n, 7H and 9He via transfer reactions

Fortier, S.; Tryggestad, E.; Rich, Evan A.; Beaumel, D.; Becheva, E.; Blumenfeld, Y.; Delaunay, F.; Drouart, A.; Fomichev, A. S.; Frascaria, N.; Galès, S.; Gaudefroy, L.; Gillibert, A.; Guillot, J.; Hammache, F.; Kemper, K. W.; Khan, E.; Lapoux, V.; Lima, V. Franco; Nalpas, L.; Obertelli, A.; Pollacco, E. C.; Skaza, F.; Pramanik, U. Datta; Roussel‐Chomaz, P.; Santonocito, D.; Scarpaci, J. A.; Sorlin, O.; Stepantsov, S. V.; Akopian, G. M. Ter; Wolski, R.

doi:10.1063/1.2746575

Cited by 12 publications

(19 citation statements)

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“…These results were also consistent with shell model calculations [49]. The presence of a 1/2 + state was also reported in subsequent works [40][41][42][43][44]46], although a smaller absolute value of the S-wave scattering length a 0 ∼ −3 fm was reported in particular in Refs. [41][42][43].…”

Section: Introductionsupporting

confidence: 91%

Structure of the exotic He9 nucleus from the no-core shell model with continuum

et al. 2018

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Background: The exotic 9 He nucleus, which presents one of the most extreme neutron-to-proton ratios, belongs to the N = 7 isotonic chain famous for the phenomenon of ground-state parity inversion with decreasing number of protons. Consequently, it would be expected to have an unnatural (positive) parity ground state similar to 11 Be and 10 Li. Despite many experimental and theoretical investigations, its structure remains uncertain. Apart from the fact that it is unbound, other properties including the spin and parity of its ground state and the very existence of additional low-lying resonances are still a matter of debate. Purpose: In this work we study the properties of 9 He by analyzing the n+ 8 He continuum in the context of the ab initio no-core shell model with continuum (NCSMC) formalism with chiral interactions as the only input. Methods: The NCSMC is a state-of-the-art approach for the ab initio description of light nuclei. With its capability to predict properties of bound states, resonances, and scattering states in a unified framework, the method is particularly well suited for the study of unbound nuclei such as 9 He. Results: Our analysis produces an unbound 9 He nucleus. Two resonant states are found at the energies of ∼1 and ∼3.5 MeV, respectively, above the n+ 8 He breakup threshold. The first state has a spin-parity assignment of J π = 1/2 − and can be associated with the ground state of 9 He, while the second, broader state has a spin-parity of 3/2 − . No resonance is found in the 1/2 + channel, only a very weak attraction. Conclusions: We find that the 9 He ground-state resonance has a negative parity and thus breaks the parity-inversion mechanism found in the 11 Be and 10 Li nuclei of the same N = 7 isotonic chain.

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Section: Introductionsupporting

confidence: 91%

Structure of the exotic He9 nucleus from the no-core shell model with continuum

et al. 2018

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“…A recent 8He(r/, p) reaction (in reverse kinematics) located it at 3.42(78) MeV. Results from several experiments [4][5][6][7][8][9][10][11][12] are listed in Table 1. The 1 /2 + and 5/2+ energies are plotted in Fig.…”

Section: "Hementioning

confidence: 98%

Constraints on energies ofHe10(0+)andHe
Fortune
¹

2015
Phys. Rev. C
9
0
1
0
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I have used the relationship between computed energies in l0He and single-particle energies in ''He to provide limits on the s\/2 energy. The absence of any bound states in l0He requires £ s > 1 MeV, contradicting all the experiments that have reported an s state near threshold. The present analysis supports the view that the variation of l0He "ground-state" (g.s.) energies determined in various reactions is caused by the presence of two overlapping 0+ resonances. Results of the two simplest reactions-proton knockout and (/, p)-have been used to extract the g.s. and excited 0+ energies as a function of the mixing parameter h2 between the p-shell and the (sd)2 basis states.

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“…The authors of Ref. [19] investigated the 2 H( 8 He, 3 He) 7 H reaction. They concluded that there was some indication of a 7 H resonance state in the measured MM spectrum at E T ∼ 2 MeV.…”

Section: A History Of the Research Subjectmentioning

confidence: 99%

“…In experiment [11] only the missing mass of 7 H was available, and background conditions were very poor: the MM spectrum extended into negative energy region down to −20 MeV, and more than 90% of the data were related to the background in the analysis. In experiment [19] also only the missing mass of 7 H was available, and background conditions were poor: the MM spectrum extended into the negative energy region down to −3 MeV, and ∼ 75% of the data were related to the background reactions originated from the carbon component of the CD 2 target. In experiment [20] the missing mass spectrum 10.…”

Section: Reliability Of Channel Identification and Background Conditionsmentioning

confidence: 99%

Resonant states in $^{7}$H. I. Experimental studies of the $^2$H($^8$He,$^3$He) reaction

Muzalevskii,

Bezbakh,

Nikolskii

et al. 2020

Preprint

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The extremely neutron-rich system 7 H was studied in the direct 2 H( 8 He, 3 He) 7 H transfer reaction with a 26 AMeV secondary 8 He beam [1]. Missing mass and center-of-mass (c.m.) angular distributions of 7 H were reconstructed, as well as the momentum distribution of the 3 H fragment in the 7 H frame. In addition to the investigation reported in Ref.[1], we carried out another experiment with the same beam but a modified setup. In the second experiment the cross-check of the experimental calibration was performed by the studies of the 2 H( 10 Be, 3 He) 9 Li reaction. There is a solid experimental evidence of the population of two resonant states in 7 H at energies of 2.2(5) and 5.5(3) MeV relative to 3 H+4n threshold. Also, there are indications on the resonant states at 7.5(3) and 11.0(3) MeV. Based on the energy and angular distributions the weakly populated 2.2(5) MeV peak is assigned as the 7 H ground state. It is highly plausible that the firmly ascertained 5.5(3) MeV state is the 5/2 + member of the 7 H excitation doublet, built on the 2 + configuration of valence neutrons. The 7.5 MeV state can be a member of this 5/2 + -3/2 + doublet of excited states, which could not be resolved in Ref. [1] and which consequently appeared in [1] as a 6.5 MeV state of 7 H.

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Search for resonances in 4n, 7H and 9He via transfer reactions

Cited by 12 publications

References 0 publications

Structure of the exotic He9 nucleus from the no-core shell model with continuum

Structure of the exotic He9 nucleus from the no-core shell model with continuum

Constraints on energies ofHe10(0+)andHe
Fortune
¹

2015
Phys. Rev. C
9
0
1
0
View full text Add to dashboard Cite

Resonant states in $^{7}$H. I. Experimental studies of the $^2$H($^8$He,$^3$He) reaction

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Search for resonances in 4n, 7H and 9He via transfer reactions

Cited by 12 publications

References 0 publications

Structure of the exotic He9 nucleus from the no-core shell model with continuum

Structure of the exotic He9 nucleus from the no-core shell model with continuum

Constraints on energies ofHe10(0+)andHeFortune1 2015Phys. Rev. C9010View full textAdd to dashboardCite

Resonant states in $^{7}$H. I. Experimental studies of the $^2$H($^8$He,$^3$He) reaction

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Product

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About

Constraints on energies ofHe10(0+)andHe
Fortune
¹

2015
Phys. Rev. C
9
0
1
0
View full text Add to dashboard Cite