One-neutron knockout from Sc51-55

作者：Schwertel S^*; Maierbeck P; Kruecken R; Gernhaeuser R; Kroell T; Alvarez Pol H; Aksouh F; Aumann T; Behr K; Benjamim E A; Benlliure J; Bildstein V; Boehmer M; Boretzky K; Borge M J G; Bruenle A; Burger A; Caamano M; Casarejos E; Chatillon A; Chulkov L V; Cortina Gil D; Enders J; Eppinger K; Faestermann T; Friese J; Fabbietti L; Gascon M; Geissel H; Gerl J; Gorska M; Hansen P G; Jonson B; Kanungo R; Kiselev O

来源：European Physical Journal A, 2012, 48(12): 191.

DOI：10.1140/epja/i2012-12191-5

Results are presented from a one-neutron knockout experiment at relativistic energies of approximate to 420 A MeV on Sc51-55 using the GSI Fragment Separator as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the contributions corresponding to knockout from the nu p(1/2), nu p(3/2), (L = 1) and nu f(7/2), nu f(5/2) (L = 3) neutron orbitals. The observed L = 1 and L = 3 contributions are compared with theoretical cross-sections using eikonal knockout theory and spectroscopic factors from shell model calculations using the GXPF1A interaction. The measured inclusive knockout cross-sections generally follow the trends expected theoretically and given by the spectroscopic strength predicted from the shell model calculations. However, the deduced L = 1 cross-sections are generally 30-40% higher while the L = 3 contributions are about a factor of two smaller than predicted. This points to a promotion of neutrons from the nu f(7/2) to the nu p(3/2) orbital indicating a weakening of the N = 28 shell gap in these nuclei. While this is not predicted for the phenomenological GXPF1A interaction such a weakening is predicted by recent calculations using realistic low-momentum interactions V-lowk obtained by evolving a chiral N3LO nucleon-nucleon potential.

• 出版日期2012-12
• 单位中国地震局