Shape transition with temperature of the pear-shaped nuclei in covariant density functional theory

Zhang, Wei; Niu, Y. F.

doi:10.1103/physrevc.96.054308

Cited by 35 publications

(17 citation statements)

References 53 publications

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“…-(f), the global minimum remains at the spherical state while the soft area shrinks, especially in the β 3 direction. Such shape evolution is similar to the evolution of 224 Ra[39], except that two shape transitions can be found for 224 Ra, namely one from quadrupoleoctupole deformed shape to quadrupole deformed shape at temperature 0.9 MeV, and the other from quadrupole deformed shape to spherical shape at temperature 1.0 MeV. This could be related to the fact that the quadrupole deformation and octupole deformation of the ground state for 292 Cm are very close (β 2 =0.177, β 3 =0.166) while those for 224 Ra…”

supporting

confidence: 64%

“…Traditionally, strong octupole correlations occur at the nucleon numbers being close to 56 (1h 11/2 ↔ 2d 5/2 coupling), 88 (1i 13/2 ↔ 2f 7/2 coupling), and 134 (1j 15/2 ↔ 2g 9/2 coupling) [40]. In previous study [39], the 224 Ra is an isotope with the neutron number 136 and the proton number 88, and the even-even 144−154 Ba isotopes locates at the neutron number 88-98 with the proton number 56. Recently, a new region centering at 292 Cm with the neutron number 196 and the proton number 96 were systematically studied and the ground-state octupole deformation were obtained by the covariant density functional theory [41].…”

Section: Introductionmentioning

confidence: 92%

“…The shape transition temperature was found between 1.7-2.1 MeV. Furthermore, the octupole correlations were taken into account and the shape evolutions of typical octupole deformed nuclei 224 Ra and even-even 144−154 Ba isotopes were studied, and these nuclei first go through an octupole shape transition where the octupole correlations disappear at temperature range 0.5-0.95 MeV, and then another quadrupole shape transition from quadrupole deformed shape to spherical shape at a higher temperature range 1.0-2.2 MeV [39]. Moreover, it was pointed out that the transition temperatures are roughly proportional to the corresponding deformations at the ground states.…”

Section: Introductionmentioning

confidence: 99%

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Critical temperature for shape transition in hot nuclei within covariant density functional theory

Zhang

Niu

2018

Phys. Rev. C

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Prompted by the simple proportional relation between critical temperature for pairing transition and pairing gap at zero temperature, we investigate the relation between critical temperature for shape transition and ground-state deformation by taking even-even 286−304 Cm isotopes as examples. The finite-temperature axially deformed covariant density functional theory with BCS pairing correlation is used. Since the Cm isotopes are the newly proposed nuclei with octupole correlations, we studied in detail the free energy surface, the Nilsson single-particle (s.p.) levels, and the components of s.p. levels near the Fermi level in 292 Cm. Through this study, the formation of octupole equilibrium is understood by the contribution coming from the octupole driving pairs with Ω[N, n z , m l ] and Ω[N + 1, n z ± 3, m l ] for single-particle levels near the Fermi surfaces as it provides a good manifestation of the octupole correlation. Furthermore, the systematics of deformations, pairing gaps and the specific heat as functions of temperature for even-even 286−304 Cm isotopes are discussed. Similar to the relation between the critical pairing transition temperature and the pairing gap at zero temperature T c = 0.6∆(0), a proportional relation between the critical shape transition temperature and the deformation at zero temperature T c = 6.6β(0) is found for both octupole shape transition and quadrupole shape transition for isotopes considered.

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supporting

confidence: 64%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Critical temperature for shape transition in hot nuclei within covariant density functional theory

Zhang

Niu

2018

Phys. Rev. C

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“…Furthermore, in the non relativistic FT-QRPA calculations axial-symmetry is assumed while the FT-PNRQRPA assumes spherical symmetry. Although a shape-phase transition is expected from deformed to a spherical state at high temperatures [90,91], deformation can persist at T = 10 GK, which leads to differences between two sets of EC rates. In Fig.…”

Section: Figmentioning

confidence: 99%

Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations

Giraud,

Ney,

Ravlić

et al. 2021

Preprint

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The temperature dependence of stellar electron-capture (EC) rates is investigated, with a focus on nuclei around N = 50, just above Z = 28, which play an important role during the collapse phase of core-collapse supernovae (CCSN). Two new microscopic calculations of stellar EC rates are obtained from a relativistic and a non-relativistic finite-temperature quasiparticle random-phase approximation approaches, for a conventional grid of temperatures and densities. In both approaches, EC rates due to Gamow-Teller transitions are included. In the relativistic calculation contributions from first-forbidden transitions are also included, and add strongly to the EC rates. The new EC rates are compared with large-scale shell model calculations for the specific case of 86 Kr, providing insight into the finite-temperature effects on the EC rates. At relevant thermodynamic conditions for core-collapse, the discrepancies between the different calculations of this work are within about one order of magnitude. Numerical simulations of CCSN are performed with the spherically-symmetric GR1D simulation code to quantify the impact of such differences on the dynamics of the collapse. These simulations also include EC rates based on two parametrized approximations. A comparison of the neutrino luminosities and enclosed mass at core bounce shows that differences between simulations with different sets of EC rates are relatively small (≈ 5%), suggesting that the EC rates used as inputs for these simulations have become well constrained.

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“…In particular, the study of thermodynamics is essential for compound nuclei, heavy ion collisions and induced fusions [1][2][3][4][5]. Studies have shown that the pairing correlation plays a very important role in these phenomena and other nuclear thermodynamic properties [6], such as the shape transition in hot nuclei [7,8], the phase diagram structure of liquid-gas phase transition [9,10], and the fragments produced in spallation reactions [11].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of pairing transition for Odd-A nuclei

Yan,

Lin,

Liu

2021

Preprint

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The hot nucleus 171 Yb is investigated by the covariant density functional theory with the PC-PK1 effective interaction. The thermodynamic quantities are evaluated with the canonical ensemble theory. The pairing correlations is treated by the shell-model-like approach, in which the particle numbers are conserved strictly and in which the blocking effect is handled exactly. An S-shaped heat capacity versus temperature of 171 Yb appears. It has been studied in terms of the blocking effect, the single-particle levels, the pairing gap, and defined seniority components, and compared to the heat capacity of 172 Yb. The pairing transition from the superfluid state to the normal state can result in the S-shaped heat capacity of 172 Yb where the one-pair-broken and two-pair-broken states dominate, while the single-particle level structure near the Fermi surface is associated with the S-shaped heat capacity of 171 Yb. For odd-A nuclei, although the one-pair-broken and two-pairbroken states still contribute, the pairing gap and the pairing transition is relatively weak. The S-shaped heat capacity could be affected due to the blocking of the single-particle level near the Fermi surface.

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Shape transition with temperature of the pear-shaped nuclei in covariant density functional theory

Cited by 35 publications

References 53 publications

Critical temperature for shape transition in hot nuclei within covariant density functional theory

Critical temperature for shape transition in hot nuclei within covariant density functional theory

Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations

Thermodynamics of pairing transition for Odd-A nuclei

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