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Nuclear Theory·nucl-th

Thursday·April 8, 2021

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    Thermodynamics of pairing transition for Odd-A nuclei

    Tao Yan🇨🇳 · Yanlong Lin🇨🇳 · Lang Liu🇨🇳

    The hot nucleus 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 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 Yb. The pairing transition from the superfluid state to the normal state can result in the S-shaped heat capacity of 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 Yb. For odd-A nuclei, although the one-pair-broken and two-pair-broken 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.

    nucl-thPRC(2021)·8 citations
  2. 02

    Measurement of Neutron Lifetime and Purcell Effect

    Fei He🇨🇳 · Ka-Di Zhu🇨🇳

    Purcell effect predicts that spontaneous radiation is not an intrinsic property of matter, but is affected by the environment in which it is located, and is the result of the interaction of matter and field. Purcell effect can be inferred from Fermi Gold rule through strict quantum electrodynamics (QED), and through it can achieve the enhancement or suppression of radiation. We suggest that, in principle, the Purcell effect can be detected at the percentage level of neutron decay in experiments with trapped ultra-cold neutrons. As a test of our claim, we propose a currently achievable experimental protocol that can detect whether Purcell effect has occurred in an trapped ultra-cold neutron lifetime measurement experiment. Finally, we discuss the discrepancy in current methods of measuring neutron lifetime, which may be caused by different experimental setups.

    nucl-thhep-phquant-ph1 citation
  3. 03

    Role of triaxiality in deformed halo nuclei

    K. Uzawa🇯🇵 · K. Hagino🇯🇵 · K. Yoshida🇯🇵

    It is known that nuclear deformation plays an important role in inducing the halo structure in neutron-rich nuclei by mixing several angular momentum components. While previous theoretical studies on this problem in the literature assume axially symmetric deformation, we here consider non-axially symmetric deformations. With triaxial deformation, the quantum number is admixed in a single-particle wave function, where is the projection of the single-particle angular momentum on the symmetric axis, and the halo structure may arise even when it is absent with the axially symmetric deformation. In this way, the area of halo nuclei may be extended when triaxial deformation is considered. We demonstrate this idea using a deformed Woods-Saxon potential for nuclei with neutron number N=13 and 43.

    nucl-thnucl-exPRC(2021)·9 citations
  4. 04

    Single-nucleon removal cross sections on nucleon and nuclear targets

    J.A. Tostevin🇯🇵

    The eikonal direct-reaction model, as used in spectroscopic studies of intermediate-energy nucleon-removal reactions on light target nuclei, is considered in the case of a proton target and applied to neutron removal from Ne at 240 MeV/nucleon. The computed cross sections and their sensitivities are compared using an earlier detailed analysis of carbon target data. The nuclear structure input, for the Ne ground-state and Ne final states, is that deduced from the carbon target analysis. The comparisons quantify the sensitivity of the two reactions to the angular momenta and binding energies of the active valence orbitals - showing the carbon target to be relatively more efficient for removals from weakly-bound, low-, halo-like orbitals. Probing this sensitivity experimentally would provide useful tests of these predictions and of the model's description of the reaction mechanism.

    nucl-thnucl-ex3 citations
  5. 05

    Fermion Pair Dynamics in Open Quantum Systems

    S. M. Wang🇺🇸 · W. Nazarewicz🇺🇸

    Three-body decay is a rare decay mode observed in a handful of unbound rare isotopes. The angular and energy correlations between emitted nucleons are of particular interest, as they provide invaluable information on the interplay between structure and reaction aspects of the nuclear open quantum system. To study the mechanism of two-nucleon emission, we developed a time-dependent approach that allows us to probe emitted nucleons at long times and large distances. We successfully benchmarked the new method against the Green's function approach and applied it to low-energy two-proton and two-neutron decays. In particular, we studied the interplay between initial-state nucleon-nucleon correlations and final-state interaction. We demonstrated that the time evolution of the two-nucleon wave function is strongly impacted by the diproton/dineutron dynamics and that the correlations between emitted nucleons provide invaluable information on the dinucleon structure in the initial-state.

    nucl-thnucl-exPRL(2021)·52 citations

Affiliations

first authorsco-authorsvia INSPIRE