Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Seidlitz, M., Muecher, D., Reiter, P., Bildstein, V., Blazhev, A., Bree, N., ... Wiens, A. (2011). Coulomb excitation of , 181-186. https://doi.org/10.1016/j.physletb.2011.05.009 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 11-04-2019Physics Letters B 700 (2011) © 2011 Elsevier B.V. All rights reserved. MotivationShell structure is one of the most important frameworks for understanding nuclear structure and the properties of atomic nuclei. Recent experimental and theoretical findings indicate that magic numbers are subject to the proton-to-neutron ratio and new magic numbers are revealed when going to more exotic nuclei. Such a new magic number was proposed at N = 16 for some nuclei be- ground state for these nuclei [6]. Later shell model calculations by Warburton et al. [7] showed that the 1 f 7/2 orbital becomes lower in energy, reducing the sd shell gap and an anomalous inverted level structure was proposed, which is based on 2-particle 2-hole (2p2h) neutron cross shell configurations in the ground state. ExperimentThe Coulomb excitation experiment was performed at the REX-ISOLDE facility at CERN [37,38] The scattered beam and recoiling target nuclei were detected by a CD-shaped 500 μm thick double sided silicon strip detector (DSSSD), consisting of four identical quadrants [40]. Each quadrant comprised 16 annular strips at the front side and 24 radial strips at the back side for identification and reconstruction of the trajectories of the scattered nuclei. The detector covered forward angles between 16.4 • and 53.3 • in the laboratory system. De-excitation γ -rays following Coulomb excitation of projectile and target nuclei were detected by the MINIBALL γ -spectrometer, consisting of eight triple cluster detectors in close geometry, each containing three 6-fold segmented HPGe crystals [41]. The photopeak efficiency of the array at 1.3 MeV was 8% after cluster addback. The high segmentation of the setup ensured a proper Doppler correction for in-flight γ -ray emission at v/c ∼ 8% by combining the angular information of the γ -ray with the direction and velocity of the scattered beam particle that was detected in coincidence.Two additional particle detectors were used downstream after the scattering chamber to monitor the position of the beam and M. Seidlitz et al. / Physics Letters B ...