One-neutron knockout from 51–55 Sc

Autor: I. Kojouharov, M. Böhmer, C. Rodriguez-Tajes, T. Le Bleis, Ángel Perea, C. Pascual-Izarra, P. G. Hansen, Th. Kröll, D. Cortina-Gil, M. Caamaño, M. Gascon, E. A. Benjamim, Björn Jonson, Olof Tengblad, Roman Gernhäuser, O. Kiselev, Gunnar Nyman, D. Perez, S. Schwertel, Thomas Nilsson, J. Benlliure, A. Brünle, K. Sümmerer, Enrique Casarejos, R. Krücken, L. V. Chulkov, Kristian Larsson, B. A. Brown, M. Górska, K. Eppinger, L. Maier, Helmut Weick, H. Alvarez-Pol, A. Klimkiewicz, P. Maierbeck, A. Prochazka, A. Chatillon, T. Faestermann, Hans Geissel, S. Winkler, J. Gerl, V. Bildstein, K.-H. Behr, A. Bürger, M. J. G. Borge, Joachim Enders, G. Schrieder, Takaharu Otsuka, D. Rossi, Laura Fabbietti, K. Boretzky, H. Schaffner, M. Stanoiu, T. Kurtukian, Thomas Aumann, Branislav Sitar, N. Kurz, Herbert A. Simon, K. Mahata, Rituparna Kanungo, J. Friese, C. Nociforo, W. D. M. Rae, F. Aksouh, J. A. Tostevin
Rok vydání: 2012
Předmět:
Zdroj: The European Physical Journal A. 48
ISSN: 1434-601X
1434-6001
DOI: 10.1140/epja/i2012-12191-5
Popis: Results are presented from a one-neutron knockout experiment at relativistic energies of $ \approx 420 A$ MeV on 51-55Sc 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_{low k}$ obtained by evolving a chiral N3LO nucleon-nucleon potential.
Databáze: OpenAIRE
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