Nuclear level densities and 
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-ray strength functions in samarium isotopes

Naqvi, F.; Simón, A.; Guttormsen, M.; Schwengner, R.; Frauendorf, S.; Reingold, Craig; Burke, J. T.; Cooper, Nathan; Hughes, R. O.; Ota, S.; Saastamoinen, A.

doi:10.1103/physrevc.99.054331

Cited by 18 publications

(15 citation statements)

References 47 publications

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“…It was found that the low-energy M 1 strength decreases and the scissors strength develops when going into the open shell. The simultaneous appearance of the two M 1 modes is in accordance with experimental findings in Sm isotopes [6,7]. Later on, M 1 strength functions were calculated for isotopic series in various mass regions [16][17][18].…”

Section: Introductionsupporting

confidence: 83%

“…First observed in 56,57 Fe [3], the upbend was found also in various nuclides in other mass regions, such as in Mo isotopes [4], in 105,106 Cd [5], and in Sm isotopes [6,7]. The experiments used light-ion induced reactions such as ( 3 He, 3 He'), and the data were analyzed with the so-called Oslo method to extract level densities and γ-SFs.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of low-lying M1 modes in germanium isotopes

Frauendorf,

Schwengner

2021

Preprint

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Magnetic dipole strength functions are determined for the series of germanium isotopes from N = Z = 32 to N = 48 on the basis of a large number of transition strengths calculated within the shell model. The evolution of the strength with increasing neutron number in the 1g 9/2 orbital is analyzed. A bimodal structure comprising an enhancement toward low transition enery and a resonance in the region of the scissors mode is identified. The low-energy enhancement is strongest near closed shells, in particular at the almost completely filled 1g 9/2 orbital, while the scissorslike resonance is most pronounced in the middle of the open shell, which correlates with the magnitude of the also deduced electric quadrupole transition strengths. The results are consistent with previous findings for the shorter series of iron isotopes and proves the occurrence and correlation of the two low-lying magnetic dipole modes as a global structural feature.

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Section: Introductionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Evolution of low-lying M1 modes in germanium isotopes

Frauendorf,

Schwengner

2021

Preprint

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“…[11] concluded that the bimodal structure gradually develops with increasing N by shifting strength from the LEMAR spike to the SR while the sum stays nearly constant. The gradual development of the SR and the shift of the integrated strength when entering a shell has been confirmed experimentally for odd-A Sm isotopes [18]. Systematic calculations using the full pf shell as configuration space for the Ge isotopes [19] and the Ga isotopes [9] show that near the closed shells N = 28 and 50 only the LEMAR spike exists.…”

Section: Deformationmentioning

confidence: 88%

Decoherence of collective motion in warm nuclei

et al. 2019

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Collective states in cold nuclei are represented by a wave function that assigns coherent phases to the participating nucleons. The degree of coherence decreases with excitation energy above the yrast line because of coupling to the increasingly dense background of quasiparticle excitations. The consequences of decoherence are discussed, starting with the well studied case of rotational damping. In addition to superdeformed bands, a highly excited oblate band is presented as a new example of screening from rotational damping. Suppression of pair correlation leads to incoherent thermal M1 radiation, which appears as an exponential spike (LEMAR) at zero energy in the γ strength function of spherical nuclei. In deformed nuclei a Scissors Resonance appears and LEMAR changes to damped magnetic rotation, which is interpreted as partial restoration of coherence.

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“…In the shell-model calculations, such a bump appears in open-shell nuclei and has been related to the scissors resonance, which develops in deformed nuclides [75]. A pronounced bump around 3 MeV in addition to the low-energy upbend was also observed in Sm isotopes [76,77].…”

Section: Discussionmentioning

confidence: 99%

Photoexcitation of $^{76}$Ge

Schwengner,

Massarczyk,

Schmidt

et al. 2021

Preprint

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The dipole strength of the nuclide 76 Ge was studied in photon-scattering experiments using bremsstrahlung produced with electron beams of energies of 7.8 and 12.3 MeV at the γELBE facility. We identified 210 levels up to an excitation energy of 9.4 MeV and assigned spin J = 1 to most of them. The quasicontinuum of unresolved transitions was included in the analysis of the spectra and the intensities of branching transitions were estimated on the basis of simulations of statistical γ-ray cascades. The photoabsorption cross section up to the neutron-separation energy was determined and is compared with predictions of the statistical reaction model. The derived photon strength function is compared with results of experiments using other reactions.

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Nuclear level densities and γ -ray strength functions in samarium isotopes

Cited by 18 publications

References 47 publications

Evolution of low-lying M1 modes in germanium isotopes

Evolution of low-lying M1 modes in germanium isotopes

Decoherence of collective motion in warm nuclei

Photoexcitation of $^{76}$Ge

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