Shell structure of the neutron-rich isotopes <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Co</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>69</mml:mn><mml:mo>,</mml:mo><mml:mn>71</mml:mn><mml:mo>,</mml:mo><mml:mn>73</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>
T. Lokotko, Sylvain Leblond, J. Lee, P. Doornenbal, A. Obertelli, A. Poves, F. Nowacki, Kazuyuki Ogata, K. Yoshida, G. Authelet, H. Baba, D. Calvet, F. Château, S. Chen, A. Corsi, A. Delbart, J.-M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Nııkura, H. Otsu, Clara Péron, A. Peyaud, E. C. Pollacco, J.-Y. Roussé, H. Sakuraï, C. Santamaria, Z. Y. Xu, M. Sasano, Yoshinori Shiga, Satoshi Takeuchi, R. Taniuchi, Т. Уесака, H. Wang, V. Werner, F. Browne, L. X. Chung, Zs. Dombrádi, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadyńska-Klęk, Z. Korkulu, S. Koyama, Y. Kubota, M. Lettmann, C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, L. Olivier, S. Ota, Z. Patel, E. Şahin, C. Shand, P.-A. Söderström, I. Stefan, D. Steppenbeck, T. Sumikama, Daisuke Suzuki, Zs. Vajta, J. Wu
Abstract
The structures of the neutron-rich $^{69,71,73}\mathrm{Co}$ isotopes were investigated via $(p,2p)$ knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Isotopes of interest were studied using the DALI2 $\ensuremath{\gamma}$-ray detector array combined with the MINOS target and tracker system. Level schemes were reconstructed using the $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations using the Lenzi-Nowacki-Poves-Sieja LNPS and PFSDG-U interactions suggests coexistence of spherical and deformed shapes at low excitation energies in the $^{69,71,73}\mathrm{Co}$ isotopes. The distorted-wave impulse approximation (DWIA) framework was used to calculate the single-particle cross sections. These values were compared with the experimental findings.