Evolution of the 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>20</mml:mn></mml:mrow></mml:math>
 and 28 shell gaps and two-particle-two-hole states in the FSU interaction

Lubna, R. S.; Kravvaris, Konstantinos; Tripathi, S.; Rubino, E.; Volya, Alexander

doi:10.1103/physrevresearch.2.043342

Cited by 31 publications

(15 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Additionally, our group has recently developed a new spsdpf crossshell interaction. It has been quite successful in predicting higher-spin cross-shell excitations in nuclei a little lighter than A ≈ 40 and is compared to our experimental results further on [4][5][6].…”

Section: Introductionmentioning

confidence: 69%

See 1 more Smart Citation

Multiparticle-hole excitations in nuclei near N = Z = 20: $^{41}$K

Rubino,

Tabor,

Tripathi

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

This experimental study of high-spin structure near N = Z = 20 nuclei was focused on 41 K, but will also mention three newly observed γ transitions in 41 Ca observed in the same reaction. Highspin states were populated using the 26 Mg( 18 O, p2nγ) 41 K and 26 Mg( 18 O, 3nγ) 41 Ca reactions. The experiment was carried out at an incident beam energy of 50 MeV at the Florida State University (FSU) John D. Fox Superconducting Linear Accelerator Laboratory and used the FSU high-purity germanium detector array. The 41 K level scheme was extended to 12325 keV, possibly with J π = 25/2 − or 27/2 + , by means of 25 new transitions and that of 41 Ca to 9916 keV. Linear polarization and a measure of angular distribution results are also reported and used to provide information on the spins and parities of several states in the 41 K decay scheme. The results have been compared to the spsdpf cross-shell FSU shell model interaction calculations. The theoretical results from configurations involving no or one additional nucleon promoted from the sd to the f p shell agree relatively well with the energies of known states, while those that involve multi-particle excitations paint an interesting and complex picture of interplay between single-particle excitations, collective pairing, and deformation. This presents an interesting challenge for future theory.

show abstract

Section: Introductionmentioning

confidence: 69%

“…In fact when looking for further FIG.10. A comparison of the low lying experimental states in 41 K with the FSU[5,6] and PSDPF shell model interaction calculations illustrating the improved agreement with the FSU interaction.…”

mentioning

confidence: 94%

Multiparticle-hole excitations in nuclei near N = Z = 20: $^{41}$K

Rubino,

Tabor,

Tripathi

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The ground-state to ground-state two-proton separation energy is 40.80 MeV [18], driving the direct nature of the 2p reaction mechanism [19]. Both, the 2p, 31 Ne(J π )| 33 Mg(3/2 − ) overlaps that generate the Two-Nucleon Amplitudes (TNAs) of the removed sdshell protons, and the spectrum of unbound excited 31 Ne final states are taken from the FSU interaction [20] shellmodel calculations made using the code nushellx [21]. The FSU Hamiltonian uses the sd-pf model space with the constraint that the protons are in the sd shell.…”

Section: Resultsmentioning

confidence: 99%

Neutron-unbound states in Ne31

et al. 2021

View full text Add to dashboard Cite

Background: The Island of Inversion near the N = 20 shell gap is home to nuclei with reordered single-particle energy levels compared to the spherical shell model. Studies of 31 Ne have revealed that its ground state has a halo component, characterized by a valence neutron orbiting a deformed 30 Ne 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 31 Ne that decay by the emission of a single neutron.Methods: An 89 MeV/nucleon 33 Mg beam impinged on a segmented Be reaction target. Neutron-unbound states in 31 Ne were populated via a two-proton knockout reaction. The 30 Ne fragment and associated neutron from the decay of 31 Ne 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 ( 30 Ne + 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 line shape 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 31 Ne.Conclusions: Excited states in 31 Ne were observed for the first time. Transitions from calculated shell model final states in 31 Ne to bound states in 30 Ne are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating 31 Ne states as well as spectroscopic factors pertaining to the decay of 31 Ne into 30 Ne are used to examine the results within the context of the shell model expectations.

show abstract

“…In this work we were able to make a substantial progress in understanding of clustering from a theoretical perspective, we take advantage of a new phenomenological shell model Hamiltonian [38][39][40] that has been developed to study cross-shell particle hole excitations. While particle-hole hierarchy in the theoretical approach may seem like a disadvantage in this work it played a crucial role in identifying clustering channels, allowing to determine origins of seemingly excessive clustering strength observed in experiments.…”

Section: Discussionmentioning

confidence: 99%

“…These Hamiltonians are remarkably accurate, some good examples describe thousands of states seen in experiments along with their properties; they re-liably predict states and are often used for guidance in experimental searches. Recently a new FSU interaction Hamiltonian has been developed [38][39][40] where cross-shell matrix elements between p, sd, and f p shells have been determined using the latest data on masses and energies of intruder states. The FSU interaction Hamiltonian is among the most broad in its region of applicability covering a valence space from the s shell to f p shell, it has been demonstrated to be remarkably accurate, and works well for exotic states with multi-particle cross shell excitations that were not a part of the fit.…”

Section: Theorymentioning

confidence: 99%

The Lowest Broad Alpha Cluster Resonances in $^{19}$F

Volya,

Goldberg,

Nurmukhanbetova

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Background: There is a deep astrophysical interest in the structure of 19 F states close to the alpha decay threshold. The nuclear structure of these states is important for understanding of the development of α clustering in the 20 Ne region. Emergence of clustered states and generally states that favor coupling to reaction channels near the corresponding decay thresholds is currently of special interest in theoretical physics. The only detailed high energy resolution 15 N(α,α) work was made in 1961, and a complete analysis of these data has never been made.Purpose: To identify the parameters of broad low spin states in 19 F near the α decay threshold, to present a theoretical study of these states and to assess the current state of the theoretical methods.Method: Excitation function for 15 N(α,α) elastic scattering was measured by the TTIK method. These new data together with old, high energy resolution data, were analyzed using the R matrix approach. 19 F nuclear structure was calculated using configuration interaction methods with the recently developed effective interaction Hamiltonian. Results:The parameters of broad low spin ℓ = 0 and 1 relative partial wave resonances close to the α decay threshold in 19 F were identified. Detailed theoretical analysis was carried out identifying all states coupled to the ℓ = 0 and 1 alpha cluster channels. Considering hierarchy of states with different harmonic oscillator shell excitations allows to evaluate coupling to the alpha channels with different number of nodes in the relative wave function and helps to explain the distribution of the clustering strength and emergence of broad clustering resonances. Comparison of clustering in 20 Ne into 16 O+α and consideration of spin-orbit splitting of the 15 N+α channel provides additional evidence.Conclusions: Detailed analysis of new and old experimental data allows to identify a series of α clustering resonances in 19 F and to assess the distribution of the clustering strength which is of importance to questions of astrophysics and for theoretical understanding of many-body physics and emergence of clustering in loosely bound or unstable nuclei. Progress has been made in theoretical understanding of the origins of clustering and questions for future theoretical and experimental research are identified.

show abstract

Evolution of the N=20 and 28 shell gaps and two-particle-two-hole states in the FSU interaction

Cited by 31 publications

References 41 publications

Multiparticle-hole excitations in nuclei near N = Z = 20: $^{41}$K

Multiparticle-hole excitations in nuclei near N = Z = 20: $^{41}$K

Neutron-unbound states in Ne31

The Lowest Broad Alpha Cluster Resonances in $^{19}$F

Contact Info

Product

Resources

About