Precision Mass Measurements of Neutron-Rich Scandium Isotopes Refine the Evolution of N=32 and N=34 Shell Closures

The LEBIT Collaboration and the TITAN Collaboration

doi:10.1103/PhysRevLett.126.042501

Precision Mass Measurements of Neutron-Rich Scandium Isotopes Refine the Evolution of N=32 and N=34 Shell Closures

The LEBIT Collaboration and the TITAN Collaboration

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23 Scopus citations

Abstract

We report high-precision mass measurements of Sc50-55 isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for Sc53-55. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers N=32 and N=34 above proton-magic Z=20. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the N=32 isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic Ca52. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in Sc55 at N=34. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing N=32 neutron shell gap energies but were highly disparate in the description of the N=34 isotone.

Original language	English
Article number	042501
Journal	Physical Review Letters
Volume	126
Issue number	4
DOIs	https://doi.org/10.1103/PhysRevLett.126.042501
State	Published - Jan 26 2021
Externally published	Yes

Funding

The authors would like to thank J. Simonis and P. Navrátil for providing the and matrix element files and S. R. Stroberg for the imsrg ++ code used to perform the VS-IMSRG calculations. We are grateful to Z. Meisel for the fruitful discussions regarding data obtained in previous experiments. We also thank NSCL staff, the ISAC Beam Delivery group, the TRILIS group, and M. Good for their technical support, as well as J. Bergmann for his assistance with analysis software employed in this work. This work was conducted with the support of Michigan State University, the U.S. National Science Foundation under Contracts No. PHY-1565546 and No. PHY-1811855, the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award No. DE-SC0015927, the Natural Sciences and Engineering Research Council (NSERC) of Canada through Contract No. SAPPJ-2018-00015 and the National Research Council (NRC) of Canada through TRIUMF. E. D. acknowledges financial support from the U.K.-Canada foundation. M. P. R. acknowledges support from BMBF (Grants No. 05P16RGFN1 and No. 05P19RGFN8), Hessisches Ministerium für Wissenschaft und Kunst (HMWK) through the LOEWE Center HICforFAIR, by the JLU and GSI Helmholtzzentrum für Schwerionenforschung under the JLU-GSI strategic Helmholtz partnership agreement. A. A. V. acknowledges support from NSERC (Canada) under Contract No. SAPPJ-2018-00028.

Funders	Funder number
Office of Nuclear Physics	DE-SC0015927
U.K.-Canada Foundation
U.S. National Science Foundation	PHY-1565546, PHY-1811855
National Science Foundation	1811855
National Science Foundation
U.S. Department of Energy
Office of Science
Michigan State University
TRIUMF
National Research Council
Natural Sciences and Engineering Research Council of Canada	SAPPJ-2018-00015
Natural Sciences and Engineering Research Council of Canada
Bundesministerium für Bildung und Forschung	05P19RGFN8, 05P16RGFN1
Bundesministerium für Bildung und Forschung
Hessisches Ministerium für Wissenschaft und Kunst
Jilin University
GSI Helmholtzzentrum für Schwerionenforschung GmbH	SAPPJ-2018-00028
GSI Helmholtzzentrum für Schwerionenforschung GmbH

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10.1103/PhysRevLett.126.042501

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@article{647e7c445a404edd965c613151d430ff,

title = "Precision Mass Measurements of Neutron-Rich Scandium Isotopes Refine the Evolution of N=32 and N=34 Shell Closures",

abstract = "We report high-precision mass measurements of Sc50-55 isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for Sc53-55. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers N=32 and N=34 above proton-magic Z=20. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the N=32 isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic Ca52. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in Sc55 at N=34. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing N=32 neutron shell gap energies but were highly disparate in the description of the N=34 isotone.",

author = "{The LEBIT Collaboration and the TITAN Collaboration} and E. Leistenschneider and E. Dunling and G. Bollen and Brown, {B. A.} and J. Dilling and A. Hamaker and Holt, {J. D.} and A. Jacobs and Kwiatkowski, {A. A.} and T. Miyagi and Porter, {W. S.} and D. Puentes and M. Redshaw and Reiter, {M. P.} and R. Ringle and R. Sandler and Sumithrarachchi, {C. S.} and Valverde, {A. A.} and Yandow, {I. T.}",

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

year = "2021",

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doi = "10.1103/PhysRevLett.126.042501",

language = "English",

volume = "126",

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T1 - Precision Mass Measurements of Neutron-Rich Scandium Isotopes Refine the Evolution of N=32 and N=34 Shell Closures

AU - The LEBIT Collaboration and the TITAN Collaboration

AU - Leistenschneider, E.

AU - Dunling, E.

AU - Bollen, G.

AU - Brown, B. A.

AU - Dilling, J.

AU - Hamaker, A.

AU - Holt, J. D.

AU - Jacobs, A.

AU - Kwiatkowski, A. A.

AU - Miyagi, T.

AU - Porter, W. S.

AU - Puentes, D.

AU - Redshaw, M.

AU - Reiter, M. P.

AU - Ringle, R.

AU - Sandler, R.

AU - Sumithrarachchi, C. S.

AU - Valverde, A. A.

AU - Yandow, I. T.

PY - 2021/1/26

Y1 - 2021/1/26

N2 - We report high-precision mass measurements of Sc50-55 isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for Sc53-55. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers N=32 and N=34 above proton-magic Z=20. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the N=32 isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic Ca52. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in Sc55 at N=34. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing N=32 neutron shell gap energies but were highly disparate in the description of the N=34 isotone.

AB - We report high-precision mass measurements of Sc50-55 isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for Sc53-55. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers N=32 and N=34 above proton-magic Z=20. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the N=32 isotone, confirming that the empirical neutron shell gap energies peak at the doubly magic Ca52. Moreover, our data, combined with other recent measurements, do not support the existence of a closed neutron shell in Sc55 at N=34. The results were compared to predictions from both ab initio and phenomenological nuclear theories, which all had success describing N=32 neutron shell gap energies but were highly disparate in the description of the N=34 isotone.

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Precision Mass Measurements of Neutron-Rich Scandium Isotopes Refine the Evolution of N=32 and N=34 Shell Closures

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