Coulomb excitation of 31Mg

Abstract

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 ...

Exploringsd-shell nuclei from two- and three-nucleon interactions with realistic saturation properties

“…This is probably related to the underbinding of the sd-shell calculations when valence neutron-neutron interactions are dominant. We also note that around N = 20, the ground states of 29,30 Ne [44,45], 30,31 Na [46,47], and 31,32 Mg [48,49] are dominated by deformed configurations not captured in our sd-shell calculations (this is the so-called island of inversion). Consequently, our bands do not reproduce the change in slope of S 2n around N = 20 for Ne, Na, or Mg.…”

Nuclear-structure studies of exotic nuclei with MINIBALL

“…This value corroborates the findings from the ground-state configuration with its intruder configuration. The given values comprise results from experiments performed at RIKEN [58,62], MSU [59,60], GANIL [59,60] and at ISOLDE employing safe CE [11,13,63] and the fast-timing technique after β decay [64]. While for  N 18 the experimental values are well reproduced by USD shell-model calculations [65], large deviations are found for  N 20.…”

“…The initial physics program suggested by the proposal for the MINIBALL at REX-ISOLDE started with a thorough investigation of neutron-rich Na and Mg nuclei in the vicinity of the N=20 shell by means of Coulomb excitation (CE) and neutron-transfer reactions [10][11][12][13][14][15]. Simultaneously experiments along the chains of neutron-rich Ni, Cu and Zn isotopes were pursued in order to study collective and single particle properties in the vicinity of N=40 and the doubly-magic configuration at 78 Ni [16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Coulomb excitation of29,30Na: Mapping the borders of the island of inversion

“…For Doppler correction, all angles of the cluster detectors had to be known exactly. Therefore an angle-calibration measurement was performed, using Dopplershifted γ rays after the neutron pick-up reaction d( 22 Ne, 23 Ne)p. 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. Data of the Coulomb-excitation measurements were recorded using prompt particle-γ coincidences, i.e., events with a maximum time difference of typically 800 ns between particle and γ ray were registered.…”

“…More recently it could be confirmed that already at N = 19 the wave functions of the ground and low-lying states contain a dominant admixture of intruder configurations [21][22][23]. For the neighboring N = 18,19 Na isotopes, 29,30 Na, measurements of the magnetic dipole moments and electric quadrupole moments revealed significant deviations from the universal sd-shell (USD) model [24,25], indicating a dramatic change in the underlying shell structure also for these nuclei.…”