Open Access

Matthias Holl, Valerii Panin, Héctor Álvarez-Pol, Leyla Atar, Thomas Aumann, Saul Beceiro-Novo, Jose Fernando Benlliure Anaya, Carlos A. Bertulani, Juan Manuel Boillos Betete, Konstanze Boretzky, Manuel Caamaño, Christoph Caesar, Enrique Casarejos Ruiz, Wilton N. Catford, Joakim Cederkäll, Leonid V. Chulkov, Dolores Cortina Gil, Edgar Cravo, Iris Dillmann, Paloma Díaz Fernández, Zoltán Elekes, Joachim Enders, Luis Mario Fraile Prieto, Daniel Galaviz Redondo, Roman Gernhäuser, Pavel Golubev, Tanja Heftrich, Michael Heil, Marcel Heine, Andreas Heinz, Ana Maria Henriques Correia, Håkan T. Johansson, Björn Jonson, Nasser Kalantar-Nayestanaki, Rituparna Kanungo, Aleksandra Kelic-Heil, Thorsten Kröll, Nikolaus Kurz, Christoph Langer, Tudi Le Bleis, Simon Lindberg, Jorge Machado, Enrique Nácher González, Mohammad Ali Najafi, Thomas Nilsson, Chiara Nociforo, Stefanos Paschalis, Marina Petri, René Reifarth, Guillermo Ribeiro Jimenez, Catherine Rigollet, Dominic M. Rossi, Deniz Savran, Heiko Scheit, Haik Simon, Olivier Sorlin, Ina Syndikus, Olof Tengblad, Yasuhiro Togano, Marine Vandebrouck, Paulo Velho, Felix Wamers, Helmut Weick, Carl Wheldon, Gemma Louise Wilson, John S. Winfield, Philip John Woods, Mikhail V. Zhukov, Kai Zuber

• The quasi-free scattering reactions 11C(p, 2p) and 10,11,12C(p, pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and protonneutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C(p, 2p) and 12C(p, pn) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of singleparticle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for (p, 2p) are found to be ’significantly smaller than for (p, pn) reactions for all investigated nuclei.