Neutron-unbound states in Ne 31

D. Chrisman; A. N. Kuchera; T. Baumann; A. Blake; B. A. Brown; J. Brown; C. Cochran; P. A. Deyoung; J. E. Finck; N. Frank; P. Guèye; H. Karrick; H. Liu; J. McDonaugh; T. Mix; B. Monteagudo; T. H. Redpath; W. F. Rogers; R. Seaton-Todd; A. Spyrou; K. Stiefel; M. Thoennessen; J. A. Tostevin; D. Votaw

doi:10.1103/PhysRevC.104.034313

Neutron-unbound states in Ne 31

D. Chrisman
, A. N. Kuchera
, T. Baumann
, A. Blake
, B. A. Brown
, J. Brown
, C. Cochran
, P. A. Deyoung
, J. E. Finck
, N. Frank
, P. Guèye
, H. Karrick
, H. Liu
, J. McDonaugh
, T. Mix
, B. Monteagudo
, T. H. Redpath
, W. F. Rogers
, R. Seaton-Todd
, A. Spyrou

K. Stiefel, M. Thoennessen, J. A. Tostevin, D. Votaw

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

Background: The island of inversion near the N=20 shell gap is home to nuclei with reordered single-particle energy levels compared with the spherical shell model. Studies of Ne31 have revealed that its ground state has a halo component characterized by a valence neutron orbiting a deformed Ne30 core. This lightly bound nucleus with a separation energy of only Sn=170 keV is expected to have excited states that are neutron unbound. Purpose: The purpose of this experiment was to investigate the low-lying excited states in Ne31 that decay by the emission of a single neutron. Methods: An 89 MeV/nucleon Mg33 beam impinged on a segmented Be reaction target. Neutron-unbound states in Ne31 were populated via a two-proton knockout reaction. The Ne30 fragment and associated neutron from the decay of Ne31 were detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant-mass spectroscopy was used to reconstruct the two-body decay energy (Ne30+n). Results: The two-body decay energy spectrum exhibits two features: a low-lying peak at 0.30±0.17 MeV and a broad enhancement at 1.50±0.33 MeV, each fit with an energy-dependent asymmetric Breit-Wigner lineshape representing a resonance in the continuum. Accompanying shell-model calculations using the FSU interaction within NuShellX, combined with cross-section calculations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in Ne31. Conclusions: Excited states in Ne31 were observed for the first time. Transitions from calculated shell-model final states in Ne31 to bound states in Ne30 are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating Ne31 states as well as spectroscopic factors pertaining to the decay of Ne31 into Ne30 are used to examine the results within the context of the shell-model expectations.

Original language	English
Article number	034313
Journal	Physical Review C
Volume	104
Issue number	3
DOIs	https://doi.org/10.1103/PhysRevC.104.034313
State	Published - Sep 2021
Externally published	Yes

Funding

We would like to acknowledge the effort of the National Superconducting Cyclotron Laboratory operations staff for providing high-quality beams and device support for the Sweeper detectors. We would also like to acknowledge the MoNA collaboration for providing device support for MoNA-LISA and Sweeper detectors and contributions to the experiment execution. This work was supported by the National Science Foundation, USA under Grants No. PHY-1102511, No. PHY-1565546, No. PHY-1613188, No. PHY-1713522, No. PHY-1613429, No. PHY-1713956, No. PHY-1205357, No. PHY-2011398, and No. PHY-2012040. This work was also supported by the Department of Energy National Nuclear Security Administration, USA through the Nuclear Science and Security Consortium under Award No. DE-NA0003180 and/or DE-NA0000979. J.A.T. acknowledges support from the Science and Technology Facilities Council (UK) Grant No. ST/L005743/1.

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10.1103/PhysRevC.104.034313

Cite this

Chrisman, D., Kuchera, A. N., Baumann, T., Blake, A., Brown, B. A., Brown, J., Cochran, C., Deyoung, P. A., Finck, J. E., Frank, N., Guèye, P., Karrick, H., Liu, H., McDonaugh, J., Mix, T., Monteagudo, B., Redpath, T. H., Rogers, W. F., Seaton-Todd, R., ... Votaw, D. (2021). Neutron-unbound states in Ne 31. Physical Review C, 104(3), Article 034313. https://doi.org/10.1103/PhysRevC.104.034313

@article{19e79c0802e54c3181151c617a96f589,

title = "Neutron-unbound states in Ne 31",

abstract = "Background: The island of inversion near the N=20 shell gap is home to nuclei with reordered single-particle energy levels compared with the spherical shell model. Studies of Ne31 have revealed that its ground state has a halo component characterized by a valence neutron orbiting a deformed Ne30 core. This lightly bound nucleus with a separation energy of only Sn=170 keV is expected to have excited states that are neutron unbound. Purpose: The purpose of this experiment was to investigate the low-lying excited states in Ne31 that decay by the emission of a single neutron. Methods: An 89 MeV/nucleon Mg33 beam impinged on a segmented Be reaction target. Neutron-unbound states in Ne31 were populated via a two-proton knockout reaction. The Ne30 fragment and associated neutron from the decay of Ne31 were detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant-mass spectroscopy was used to reconstruct the two-body decay energy (Ne30+n). Results: The two-body decay energy spectrum exhibits two features: a low-lying peak at 0.30±0.17 MeV and a broad enhancement at 1.50±0.33 MeV, each fit with an energy-dependent asymmetric Breit-Wigner lineshape representing a resonance in the continuum. Accompanying shell-model calculations using the FSU interaction within NuShellX, combined with cross-section calculations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in Ne31. Conclusions: Excited states in Ne31 were observed for the first time. Transitions from calculated shell-model final states in Ne31 to bound states in Ne30 are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating Ne31 states as well as spectroscopic factors pertaining to the decay of Ne31 into Ne30 are used to examine the results within the context of the shell-model expectations.",

author = "D. Chrisman and Kuchera, \{A. N.\} and T. Baumann and A. Blake and Brown, \{B. A.\} and J. Brown and C. Cochran and Deyoung, \{P. A.\} and Finck, \{J. E.\} and N. Frank and P. Gu{\`e}ye and H. Karrick and H. Liu and J. McDonaugh and T. Mix and B. Monteagudo and Redpath, \{T. H.\} and Rogers, \{W. F.\} and R. Seaton-Todd and A. Spyrou and K. Stiefel and M. Thoennessen and Tostevin, \{J. A.\} and D. Votaw",

note = "Publisher Copyright: {\textcopyright} 2021 American Physical Society.",

year = "2021",

month = sep,

doi = "10.1103/PhysRevC.104.034313",

language = "English",

volume = "104",

journal = "Physical Review C",

issn = "2469-9985",

publisher = "American Physical Society",

number = "3",

}

Chrisman, D, Kuchera, AN, Baumann, T, Blake, A, Brown, BA, Brown, J, Cochran, C, Deyoung, PA, Finck, JE, Frank, N, Guèye, P, Karrick, H, Liu, H, McDonaugh, J, Mix, T, Monteagudo, B, Redpath, TH, Rogers, WF, Seaton-Todd, R, Spyrou, A, Stiefel, K, Thoennessen, M, Tostevin, JA & Votaw, D 2021, 'Neutron-unbound states in Ne 31', Physical Review C, vol. 104, no. 3, 034313. https://doi.org/10.1103/PhysRevC.104.034313

TY - JOUR

T1 - Neutron-unbound states in Ne 31

AU - Chrisman, D.

AU - Kuchera, A. N.

AU - Baumann, T.

AU - Blake, A.

AU - Brown, B. A.

AU - Brown, J.

AU - Cochran, C.

AU - Deyoung, P. A.

AU - Finck, J. E.

AU - Frank, N.

AU - Guèye, P.

AU - Karrick, H.

AU - Liu, H.

AU - McDonaugh, J.

AU - Mix, T.

AU - Monteagudo, B.

AU - Redpath, T. H.

AU - Rogers, W. F.

AU - Seaton-Todd, R.

AU - Spyrou, A.

AU - Stiefel, K.

AU - Thoennessen, M.

AU - Tostevin, J. A.

AU - Votaw, D.

PY - 2021/9

Y1 - 2021/9

N2 - Background: The island of inversion near the N=20 shell gap is home to nuclei with reordered single-particle energy levels compared with the spherical shell model. Studies of Ne31 have revealed that its ground state has a halo component characterized by a valence neutron orbiting a deformed Ne30 core. This lightly bound nucleus with a separation energy of only Sn=170 keV is expected to have excited states that are neutron unbound. Purpose: The purpose of this experiment was to investigate the low-lying excited states in Ne31 that decay by the emission of a single neutron. Methods: An 89 MeV/nucleon Mg33 beam impinged on a segmented Be reaction target. Neutron-unbound states in Ne31 were populated via a two-proton knockout reaction. The Ne30 fragment and associated neutron from the decay of Ne31 were detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant-mass spectroscopy was used to reconstruct the two-body decay energy (Ne30+n). Results: The two-body decay energy spectrum exhibits two features: a low-lying peak at 0.30±0.17 MeV and a broad enhancement at 1.50±0.33 MeV, each fit with an energy-dependent asymmetric Breit-Wigner lineshape representing a resonance in the continuum. Accompanying shell-model calculations using the FSU interaction within NuShellX, combined with cross-section calculations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in Ne31. Conclusions: Excited states in Ne31 were observed for the first time. Transitions from calculated shell-model final states in Ne31 to bound states in Ne30 are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating Ne31 states as well as spectroscopic factors pertaining to the decay of Ne31 into Ne30 are used to examine the results within the context of the shell-model expectations.

AB - Background: The island of inversion near the N=20 shell gap is home to nuclei with reordered single-particle energy levels compared with the spherical shell model. Studies of Ne31 have revealed that its ground state has a halo component characterized by a valence neutron orbiting a deformed Ne30 core. This lightly bound nucleus with a separation energy of only Sn=170 keV is expected to have excited states that are neutron unbound. Purpose: The purpose of this experiment was to investigate the low-lying excited states in Ne31 that decay by the emission of a single neutron. Methods: An 89 MeV/nucleon Mg33 beam impinged on a segmented Be reaction target. Neutron-unbound states in Ne31 were populated via a two-proton knockout reaction. The Ne30 fragment and associated neutron from the decay of Ne31 were detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant-mass spectroscopy was used to reconstruct the two-body decay energy (Ne30+n). Results: The two-body decay energy spectrum exhibits two features: a low-lying peak at 0.30±0.17 MeV and a broad enhancement at 1.50±0.33 MeV, each fit with an energy-dependent asymmetric Breit-Wigner lineshape representing a resonance in the continuum. Accompanying shell-model calculations using the FSU interaction within NuShellX, combined with cross-section calculations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in Ne31. Conclusions: Excited states in Ne31 were observed for the first time. Transitions from calculated shell-model final states in Ne31 to bound states in Ne30 are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating Ne31 states as well as spectroscopic factors pertaining to the decay of Ne31 into Ne30 are used to examine the results within the context of the shell-model expectations.

UR - https://www.scopus.com/pages/publications/85116009593

U2 - 10.1103/PhysRevC.104.034313

DO - 10.1103/PhysRevC.104.034313

M3 - Article

AN - SCOPUS:85116009593

SN - 2469-9985

VL - 104

JO - Physical Review C

JF - Physical Review C

IS - 3

M1 - 034313

ER -

Neutron-unbound states in Ne 31

Abstract

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