https://doi.org/10.1140/epja/s10050-024-01321-7
Regular Article - Theoretical Physics
Shape isomeric states effects on the giant monopole resonances in even-even molybdenum isotopes
1
High Energy Physics and Astrophysics Laboratory, Department of Physics, Faculty of Sciences Semlalia, Cadi Ayyad University, Street, 40000, Marrakesh, Morocco
2
ERMAM, Polydisciplinary Faculty of Ouarzazate, Ibn Zhor University, P.O.B 638, Ouarzazate, Morocco
Received:
20
November
2023
Accepted:
15
April
2024
Published online:
21
May
2024
In this work, a systematic study of the shape evolutions of the even-even molybdenum isotopes is carried out within the density-dependent meson-exchange theory. For each shape isomeric state, we have investigated the isoscalar giant monopole resonances (ISGMR) using the quasiparticle finite amplitude method (QFAM). This method allows us to explore the behavior of these resonances in various nuclear deformation. Large quadrupole deformation parameter, both in oblate and prolate configuration, causes the shoulders of ISGMR to occur in the high-energy region rather than the low-energy region. It is observed that main peak of ISGMR permutes position with the shoulders. This intriguing and noteworthy behavior is attributed to the indirect effects of deformation on the monopole response, achieved through the splitting of the neutron canonical spectrum into (J+1/2) non-degenerate states. Under spherical symmetry, only the shoulders are affected by the neutron excess. Indeed, when sub-shells are filled at the same orbital, this contributes to the shift of the shoulders toward the low-energy region while increasing their magnitudes. The observed shoulders are identified as soft monopoles, consistent with their conventional interpretation. Furthermore, the soft monopole mode can be explained also by the deformation-induced coupling between the ISGMR and the component K = 0 of isoscalar giant quadrupole resonance (ISGQR) strength.
Y. El Bassem, A. El Batoul, and M. Oulne have contributed equally to this work.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
