Observation of a dominant <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>0</mn><msub><mi>f</mi><mrow><mn>7</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> neutron configuration in the <math xmlns="http://www.w3.org/1998/Math/MathML"><mmultiscripts><mi>Si</mi><mprescripts></mprescripts><none></none><mn>32</mn></mmultiscripts><mo> </mo><mrow><msup><mi>J</mi><mi>π</mi></msup><mo>=</mo><msup><mn>5</mn><mo>−</mo></msup></mrow></math> isomeric state

C. R. Hoffman; G. L. Wilson; J. Chen; B. P. Kay; T. L. Tang; S. R. Carmichael; M. Gott; S. Lesher; M. S. Martin; G. E. Morgan; J. Wu

doi:10.1103/gw6d-9ccz

Observation of a dominant $0 f_{7 / 2}$ neutron configuration in the ${}^{32}{Si} J^{π} = 5^{-}$ isomeric state

C. R. Hoffman ^1,*, G. L. Wilson ², J. Chen^1,†, B. P. Kay ¹, T. L. Tang ¹, S. R. Carmichael ^3,‡, M. Gott ^1,§, S. Lesher ^4,∥, M. S. Martin ¹ et al.

G. E. Morgan^1,2,¶ and J. Wu.^1,**

¹Physics Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
²Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
³Department of Physics and Astronomy, University of Notre Dame, Notre Dame, Indiana 46556, USA
⁴Department of Physics and Astronomy, University of Wisconsin - La Crosse, La Crosse, Wisconsin 54601, USA

^*Contact author: crhoffman@anl.gov
^†Present address: Department of Physics, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China.
^‡Present address: Physics Division, Argonne National Laboratory, Lemont, ILlinois 60439, USA.
^§Present address: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
^∥Present address: Department of Physics, North Carolina A&T State University, Greensboro, North Carolina 27411, USA.
^¶Present address: Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA.
^**Present address: Brookhaven National Laboratory, Upton, New York 11973, USA.

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Phys. Rev. C 114, 024322 – Published 12 August, 2026

DOI: https://doi.org/10.1103/gw6d-9ccz

Abstract

An yrast, $J^{π} = 5^{-}$ , spin-trap isomer has been previously identified in ${}^{32}{Si}$ . The isomeric state decays predominantly via a hindered $E 3$ transition [ $B$ ( $E 3$ ) = 0.0841(10) W.u.], bypassing a nearby $E 2$ decay path to the first excited $3^{-}$ level. The single-neutron aspects of these negative-parity levels were investigated via the ${}^{31}{Si} (d, p) {}^{32}{Si}$ reaction at 9.6 MeV/u using HELIOS and the ATLAS in-flight facility. The $5^{-}$ state appears as a dominant $ℓ = 3$ transfer with a relatively large spectroscopic factor, confirming its single-particle $ν 0 f_{7 / 2}$ character. The yrast $3^{-}$ level had a reduced $ℓ = 3$ spectroscopic factor of approximately 0.44 compared with that of the $5_{1}^{-}$ level. This is similar to the situation observed in nearby ${}^{34}S$ , which by contrast has a measured $B$ ( $E 2, 5^{-} \to 3^{-}$ ) transition strength closer to 1 W.u. It has been concluded that the hindrance of the $5_{1}^{-} \to 3_{1}^{-}$ transition in ${}^{32}{Si}$ is not primarily due to the differing overlaps in the neutron structure. Instead, the lack of participation by both the protons and the neutrons in the transition is proposed as the transition-strength-reduction mechanism.

Physical Review C

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Observation of a dominant $0 f_{7 / 2}$ neutron configuration in the ${}^{32}{Si} J^{π} = 5^{-}$ isomeric state

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Observation of a dominant 0f7/2 neutron configuration in the Si32 Jπ=5− isomeric state

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Observation of a dominant $0 f_{7 / 2}$ neutron configuration in the ${}^{32}{Si} J^{π} = 5^{-}$ isomeric state