Mg18 was observed, for the first time, by the invariant-mass reconstruction of O14+4p events. The ground-state decay energy and width are ET=4.865(34) MeV and Γ=115(100) keV, respectively. The observed momentum correlations between the five particles are consistent with two sequential steps of prompt 2p decay passing through the ground state of Ne16. The invariant-mass spectrum also provides evidence for an excited state at an excitation energy of 1.84(14) MeV, which is likely the first excited 2+ state. As this energy exceeds that for the 2+ state in Mg20, this observation provides an argument for the demise of the N=8 shell closure in nuclei far from stability. However, in open systems this classical argument for shell strength is compromised by Thomas-Ehrman shifts.

First Observation of the Four-Proton Unbound Nucleus Mg 18 / Jin, Y., Niu, C.Y., Brown, K.W., Li, Z.H., Hua, H., Anthony, A.K., Barney, J., Charity, R.J., Crosby, J., Dell'Aquila, D., Elson, J.M., Estee, J., Ghazali, M., Jhang, G., Li, J.G., Lynch, W.G., Michel, N., Sobotka, L.G., Sweany, S., Teh, F.C.E., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 127:26(2021), p. 262502. [10.1103/PhysRevLett.127.262502]

First Observation of the Four-Proton Unbound Nucleus Mg 18

Dell'Aquila D.;
2021-01-01

Abstract

Mg18 was observed, for the first time, by the invariant-mass reconstruction of O14+4p events. The ground-state decay energy and width are ET=4.865(34) MeV and Γ=115(100) keV, respectively. The observed momentum correlations between the five particles are consistent with two sequential steps of prompt 2p decay passing through the ground state of Ne16. The invariant-mass spectrum also provides evidence for an excited state at an excitation energy of 1.84(14) MeV, which is likely the first excited 2+ state. As this energy exceeds that for the 2+ state in Mg20, this observation provides an argument for the demise of the N=8 shell closure in nuclei far from stability. However, in open systems this classical argument for shell strength is compromised by Thomas-Ehrman shifts.
2021
First Observation of the Four-Proton Unbound Nucleus Mg 18 / Jin, Y., Niu, C.Y., Brown, K.W., Li, Z.H., Hua, H., Anthony, A.K., Barney, J., Charity, R.J., Crosby, J., Dell'Aquila, D., Elson, J.M., Estee, J., Ghazali, M., Jhang, G., Li, J.G., Lynch, W.G., Michel, N., Sobotka, L.G., Sweany, S., Teh, F.C.E., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 127:26(2021), p. 262502. [10.1103/PhysRevLett.127.262502]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/256481
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