Nuclear Physics and Atomic Energy

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Nuclear Physics and Atomic Energy

  ISSN: 1818-331X (Print), 2074-0565 (Online)
  Publisher: Institute for Nuclear Research of the National Academy of Sciences of Ukraine
  Languages: Ukrainian, English
  Periodicity: 4 times per year

  Open access peer reviewed journal


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Nucl. Phys. At. Energy 2022, volume 23, issue 4, pages 223-229.
Section: Nuclear Physics.
Received: 31.10.2022; Accepted: 30.12.2022; Published online: 6.02.2023.
PDF Full text (ua)
https://doi.org/10.15407/jnpae2022.04.223

Excitation of pairing vibrations in superfluid nuclei

V. I. Abrosimov*

Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine

*Corresponding author. E-mail address: abrosim@kinr.kiev.ua

Abstract: Excitation of monopole pairing vibrations in superfluid nuclei in the two-neutron transfer reaction is studied within a kinetic model based on the semiclassical time-dependent Hartree - Fock - Bogolyubov theory. Using the anomalous (correlated) density response function, the monopole pairing mode and the amplitude of the dynamic variation of the pairing gap associated with this mode are obtained. It is shown that the pairing correlations give a coherent contribution to the spectroscopic factor for the excitation of monopole pairing vibrations in the two-neutron transfer reaction in superfluid nuclei. The contribution is determined by the distribution of neutron levels near the Fermi energy and does not exceed a few percent of the spectroscopic factor for the transfer of two neutrons to the ground state. This estimate is in agreement with experimental data for the ratio of the cross-section for excitation of the 0+-state in the (p, t)-reaction in the energy region of the monopole pairing mode, which is equal to the double pairing gap, to the cross section for excitation of the ground state in superfluid nuclei.

Keywords: pairing vibrations, anomalous density response function, kinetic model, spectroscopic factor.

References:

1. D.M. Brink, R.A. Broglia. Nuclear Superfluidity. Pairing in Finite Systems (UK: Cambridge University Press, 2005) 378 p. https://www.tandfonline.com/doi/full/10.1080/00107510902921097

2. R.A. Broglia, V. Zelevinsky (Eds.). Fifty Years of Nuclear BCS: Pairing in Finite Systems. (Singapore: World Scientific Publishing Co., 2013) 692 p. Book

3. R.A. Broglia, O. Hansen, C. Riedel. Two-nucleon Transfer Reactions and the Pairing Model. Adv. Nucl. Phys. 6 (1973) 287. https://doi.org/10.1007/978-1-4615-9041-5_3

4. W. von Oertzen, A. Vitturi. Pairing correlations of nucleons and multi-nucleon transfer between heavy nuclei. Rep. Prog. Phys. 64(10) (2001) 1247. https://doi.org/10.1088/0034-4885/64/10/202

5. A.I. Levon et al. New data on 0+ states in 158Gd. Phys. Rev. C 100 (2019) 034307. https://doi.org/10.1103/PhysRevC.100.034307

6. A.I. Levon et al. Spectroscopy of 232U in the (p, t) reaction: more information on 0+ excitations. Phys. Rev. C 92 (2015) 064319. https://doi.org/10.1103/PhysRevC.92.064319

7. A.I. Levon et al. 0+ states and collective bands in 228Th by the (p, t) reaction. Phys. Rev. C 88 (2013) 014310. https://doi.org/10.1103/PhysRevC.88.014310

8. V.I. Abrosimov et al. Self-consistency and search for collective effects in semiclassical pairing theory. Nucl. Phys. A 864 (2011) 38. https://doi.org/10.1016/j.nuclphysa.2011.06.020

9. V.I. Abrosimov et al. Kinetic equation for finite systems of fermions with pairing. Nucl. Phys. A 800 (2008) 1. https://doi.org/10.1016/j.nuclphysa.2007.11.009

10. P. Ring, P. Schuck. The Nuclear Many-Body Problem (New York: Springer-Verlag, 1980) 735 p. http://hadron.physics.fsu.edu/~akbar/NuclearTextBook.pdf

11. V.M. Strutinsky, V.I. Abrosimov. Excitation of quadrupole vibrations in two-nucleon transfer reactions. Z. Phys. A 289 (1978) 83. https://doi.org/10.1007/BF01408499

12. D.R. Bes, R. Broglia. Pairing vibrations. Nucl. Phys. 80 (1966) 289. https://doi.org/10.1016/0029-5582(66)90090-3

13. R.Y. Cusson, K. Hara. Coupling of a quasi-particle to the pairing vibrations. Z. Phys. A 209 (1968) 428. https://doi.org/10.1007/BF01380548

14. H. Olofsson, S. Aberg, P. Leboeuf. Semiclassical Theory of Bardeen-Cooper-Schrieffer Pairing-Gap Fluctuations. Phys. Rev. Lett. 100 (2008) 037005. https://doi.org/10.1103/PhysRevLett.100.037005