Compression-mode resonances in the calcium isotopes and implications for the asymmetry term in nuclear incompressibility

Howard, Kevin; Garg, U.; Itoh, Masatoshi; Akimune, H.; Bagchi, S.; Doi, Tomoko; Fujikawa, Yuki; Fujiwara, M̄.; Furuno, T.; Harakeh, Mohsen; Hijikata, Yasuto; Inaba, K.; Ishida, S.; Kalantar‐Nayestanaki, N.; Kawabata, T.; Kawashima, Shoutaro; Kitamura, Kazuya; Kobayashi, N.; Matsuda, Y.; Nakagawa, A.; Nakamura, S.; Nosaka, Kyoko; Okamoto, Soshi; Ota, S.; Weyhmiller, Sierra; Yang, Z.

doi:10.1016/j.physletb.2019.135185

Cited by 22 publications

(31 citation statements)

References 29 publications

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“…Gupta et al [8] speculated that in the case of 90,92 Zr and 92 Mo the reason for the different trends in ISGMR strengths extracted from the different experiments lies in the way that the instrumental background and physical continuum is accounted for by the TAMU and RCNP groups in their respective experiments. A similar assertion was later made for the observed discrepancies in the case of the Ca isotopes [13].…”

Section: Introductionsupporting

confidence: 79%

“…1, which are subtracted from the focused region. This method is similar to the procedure followed in experiments performed at RCNP [8,13].…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…Such an increase of the value of K A with mass number would imply that the asymmetry term in the nuclear incompressibility (K τ ) has a positive value. In an attempt to verify such an unusual phenomenon, Howard et al [13] used the experimental facilities at RCNP to study the evolution of the ISGMR strength in 40,42,44,48 Ca. As in the case of the TAMU experiments the MDA technique was employed to extract the ISGMR strength.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of the isoscalar giant monopole resonance in the Ca isotope chain

Olorunfunmi,

Neveling,

Carter

et al. 2022

Preprint

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Background: Two recent studies of the evolution of the isoscalar giant monopole resonance (ISGMR) within the calcium isotope chain report conflicting results. One study suggests that the monopole resonance energy, and thus the incompressibility of the nucleus KA increase with mass, which implies that Kτ , the asymmetry term in the nuclear incompressibility, has a positive value. The other study reports a weak decreasing trend of the energy moments, resulting in a generally accepted negative value for Kτ . Differences in the observed trends have been attributed to the use of different techniques to account for instrumental background and the physical continuum.Purpose: An independent measurement of the central region of the ISGMR in the Ca isotope chain is provided to gain a better understanding of the origin of possible systematic trends.Methods: Inelastically scattered α particles from a range of calcium targets ( 40,42,44,48 Ca), observed at small scattering angles including 0 • , were momentum analyzed in the K600 magnetic spectrometer at iThemba LABS, South Africa. Monopole strengths spanning an excitation-energy range between 9.5 and 25.5 MeV were obtained using the difference-of-spectra (DoS) technique, adjusted to allow corrections for the variation of the angular shape of the sum of the L > 0 multipoles as a function of excitation energy, and compared with previous results that employed multipole-decomposition analysis (MDA) techniques. Results:The structure of the E0 strength distributions of 40,42,44 Ca agrees well with the results from the previous measurement that supports a weak decreasing trend of the energy moments, while no two datasets agree in the case of 48 Ca. Despite the variation in the structural character of E0 strength distribution from different studies, we find for all datasets that the moment ratios, calculated from the ISGMR strength in the excitation-energy range that defines the main resonance region, display at best only a weak systematic sensitivity to a mass increase. Conclusion:Different trends observed in the nuclear incompressibility are caused by contributions to the E0 strength outside of the main resonance region, and in particular for high excitation energies. While procedures exist to identify and subtract instrumental background, more work is required to characterize and subtract continuum background contributions at high excitation energies.

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Section: Introductionsupporting

confidence: 79%

“…1, which are subtracted from the focused region. This method is similar to the procedure followed in experiments performed at RCNP [8,13].…”

Section: Experimental Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evolution of the isoscalar giant monopole resonance in the Ca isotope chain

Olorunfunmi,

Neveling,

Carter

et al. 2022

Preprint

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“…5(a). On the other hand, the rise of the centroid energy in going from 40 Ca to 48 Ca has been recently disputed based on new data [51]. In that case the behavior of the results obtained with Daejeon16 might point to some missing effects in the isovector channel.…”

Section: Phenomenological Correctionmentioning

confidence: 99%

Daejeon16 interaction with contact-term corrections for heavy nuclear systems

Papakonstantinou,

Vary,

Kim

2020

Preprint

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The Daejeon16 two-nucleon interaction is employed in many-body approaches based on the meanfield approximation. The perturbative character of Daejeon16 is verified by comparing results for 16 O from the Hartree-Fock (HF) approximation and from the no-core shell model and by examining the magnitude of perturbative corrections to the HF energy in light and heavy nuclei. In order to approximately describe energies and radii across the nuclear chart, a phenomenological correction in the form of a two-plus-three-nucleon contact interaction is introduced. With fitted parameters we achieve a very good description of medium-mass nuclei in terms of energy and size and also in terms of the centroid energy of the giant monopole resonance and the dipole polarizability calculated within the random-phase approximation (RPA). Our results provide further justification for the use of Daejeon16 augmented with phenomenological corrections as an effective interaction of perturbative character in a variety of applications.

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“…Here, we will only reiterate the major benefit provided by the ion-optics of Grand Raiden in vertical focusing mode: this arrangement renders it possible to subtract out the contributions from the instrumental background events, which underlie the true inelastic scattering spectra, based on their detected vertical positions. This feature is unique to measurements of the ISGMR at RCNP, as otherwise one is forced to account for the instrumental background and physical continuum in a phenomenological way, often with ill effect on the extracted ISGMR strength [27,29,30,31,32,33]. Inelastic-scattering data were extracted over broad angular (0 • -10 • in the laboratory frame) and excitation-energy (10-32 MeV) ranges.…”

mentioning

confidence: 99%

Compressional-mode resonances in the molybdenum isotopes: Emergence of softness in open-shell nuclei near A=90

Howard,

Garg,

Itoh

et al. 2020

Preprint

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Why are the tin isotopes soft? " has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the "doubly-closed shell" nuclei, 90 Zr and 208 Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where-and how-the softness manifests itself between 90 Zr and the cadmium and tin isotopes. The experiment was conducted using the 94,96,98,100 Mo(α, α ) reaction at E α = 386 MeV. A comparison of the results with relativistic, self-consistent Random-Phase Approximation calculations indicates that the ISGMR response begins to show softness in the molybdenum isotopes beginning with A = 92.

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Compression-mode resonances in the calcium isotopes and implications for the asymmetry term in nuclear incompressibility

Cited by 22 publications

References 29 publications

Evolution of the isoscalar giant monopole resonance in the Ca isotope chain

Evolution of the isoscalar giant monopole resonance in the Ca isotope chain

Daejeon16 interaction with contact-term corrections for heavy nuclear systems

Compressional-mode resonances in the molybdenum isotopes: Emergence of softness in open-shell nuclei near A=90

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