Role of momentum transfer in the quenching of Gamow-Teller strength

Scientific paper - Original scientific paper

• Author: Tomislav Marketin
• Author: Gabriel Martinez-Pinedo
• Author: Nils Paar
• Author: Dario Vretenar
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

Differential cross sections for the (p, n) and (n, p) reactions on 90Zr over the interval of 0–50-MeV excitation energy were used to determine the corresponding Gamow-Teller (GT) strengths, and the resulting quenching factor is ≈0.9 with respect to the Ikeda sum rule. In this procedure the contribution of the isovector spin monopole (IVSM) strength was subtracted from the total strength without taking into account the interference between the GT and the IVSM modes. Purpose was to determine the quantitative effect of the IVSM excitation mode on the L=0 strength in charge-exchange reactions on several closed-shell nuclei and the Sn isotopic chain. The fully consistent relativistic Hartree-Bogoliubov model plus proton-neutron relativistic quasiparticle random-phase approximation (pn-RQRPA) are employed in the calculation of transition strength in the β− and β+ channels. The inclusion of the higher-order terms, that include the effect of finite momentum transfer, in the transition operator shifts a portion of the strength to the high-energy region above the GT resonance. The total strength is slightly enhanced in nuclei with small neutron-to-proton ratios but remains unchanged with increasing neutron excess. Terms that include momentum transfer in the transition operator act mostly to shift the strength to high excitation energies but hardly affect the total strength. Based on the strength obtained using the full L=0 transition operator in the pn-RQRPA calculation, we have estimated the impact of the IVSM on the strength measured in the charge-exchange reactions on 90Zr and found that the data are consistent with the Ikeda sum rule.

• Keywords (english): nuclear energy density functional; Gamow-Teller strength; quasiparticle random phase approximation
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical Review C - Nuclear Physics
• Numbering: vol. 85, no. 5, 054313
• p-ISSN: 0556-2813
• e-ISSN: 1089-490X
• DOI: https://doi.org/10.1103/PhysRevC.85.054313
• URN:NBN: urn:nbn:hr:217:477630
• Publication: 2012
• Project: Number: 119-1191005-1010; Title (croatian): Nuklearna struktura i nuklearna astrofizika; Leader: Dario Vretenar; Jurisdiction: Croatia; Funding stream: ZP
• Document URL: http://link.aps.org/doi/10.1103/PhysRevC.85.054313
• Type of resource: Text
• Access conditions: Open access
• Public note: Copyright (2012) by the American Physical Society. Received 16 March 2012; published 17 May 2012.
• Created on: 2019-11-16 17:51:28