Role of direct mechanism in two-nucleon T = 0 transfer reactions in light nuclei using the ( 6 Li , α ) probe

J. C. ZAMORA, ; J. L. FERREIRA, ; A. BARIONI, ; E. N. CARDOZO, ; D. ABRIOLA,; A. ARAZI,; M. ASSUNÇÃO, ; E. DE BARBARÁ, ; M. A. CARDONA, ; V. GUIMARÃES, ; D. HOJMAN; , G. V. MARTÍ, ; D. R. MENDES, JR.,; A. J. PACHECO, ; K. C. C. PIRES,; D. RAMOS,; O. C. B. SANTOS, ; J. LUBIAN

PHYS. REV. - C

AMER PHYSICAL SOC

Lugar: New York; Año: 2022 vol. 106 p. 1460301 - 1460315

0556-2813

Background: Two-nucleon transfer reactions provide a unique tool to understand the correlation between nucleonpairs. Two-nucleon (pp, nn and np) transfer reactions can occur via isoscalar (T = 0, S = 1) or isovector(T = 1, S = 0) processes. In particular, the isoscalar pair transfer can be induced by the (a; t) or (6Li; a) probes.In the past, most of the isoscalar np-transfer studies were performed with the (a; t) reaction, but this probe isstrongly momentum mismatched with respect other two-nucleon transfer reactions.Purpose: To investigate the interplay between direct and sequential reaction mechanisms from the analysis ofexperimental (6Li; a) angular distributions in light targets.Method: Dierential cross sections of (6Li; a) reactions at the beam energy of 20 MeV were measured with 12Cand 19F targets. The interplay between direct and sequential transfer mechanisms in the experimental angulardistributions was investigated with coupled-reaction channel calculations.Results: The experimental angular distributions of isoscalar np transfer were compared with theoretical calculationsassuming a direct or a sequential reaction mechanism. Direct np-transfer calculations describe successfullymost of the angular distributions. The sequential transfer mechanism is about two orders of magnitude smallerthan the direct process.Conclusions: The present results suggest a signicant np correlation in the 12C(6Li; )14N and 19F(6Li; )21Nereactions. Despite the relatively low cross section for the reactions with the asymmetric 19F target, the directtransfer mechanism remains dominant over the sequential process. Further studies including measurements withother asymmetric sd-shell nuclei will be required to fully understand the isoscalar and isovector np-transfermechanism in this nuclear region.