Eur. Phys. J. A (2015) 51: 117
https://doi.org/10.1140/epja/i2015-15117-9

Regular Article - Experimental Physics

Nuclear structure of ^{37, 38}Si investigated by decay spectroscopy of ^{37, 38}Al

¹ Physik Department E12, Technische Universität München, D-85748, Garching, Germany
² RIKEN Nishina Center, 2-1 Hirosawa, Wako, 351-0198, Saitama, Japan
³ Department of Physics, Peking University, 100871, Beijing, China
⁴ Advanced Science Research Center, Japan Atomic Energy Agency, 319-1195, Tokai, Ibaraki, Japan
⁵ Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan
⁶ TRIUMF, 4004 Wesbrook Mall, V6T 2A3, Vancouver, British Columbia, Canada
⁷ Department of Physics and Astronomy, University of British Columbia, BC V6T 1Z1, Vancouver, BC, Canada
⁸ Department of Physics, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Chiba, Japan
⁹ Department of Physics, Tohoku University, Aoba, Sendai, 980-8578, Miyagi, Japan
¹⁰ International Research Center for Nuclei and Particles in the Cosmos, Beihang University, 100191, Beijing, China
¹¹ School of Physics and Nuclear Energy Engineering, Beihang University, 100191, Beijing, China

^* e-mail: Roman.Gernhaeuser@tum.de

Received: 21 January 2015
Revised: 21 August 2015
Accepted: 26 August 2015
Published online: 23 September 2015

Abstract

We present a study on the β decays of the neutron-rich isotopes ³⁷Al and ³⁸Al, produced by projectile fragmentation of a ⁴⁸Ca beam with an energy E = 345 A MeV at the RIKEN Nishina Center. The half-lives of ³⁷Al and ³⁸Al have been measured to 11.5(4)ms and 9.0(7)ms, respectively, using the CAITEN implantation and decay detector setup. The level schemes for ³⁷Si and ³⁸Si were deduced by employing γ-γ coincidence spectroscopy following the event-by-event identification of the implanted nuclei. Comparison to large scale nuclear shell model calculations allowed for a tentative assignment of spin and parity of the populated states. The data indicate that the classical shell gap at magic neutron number N = 28 between the νf _7/2 and νp _3/2 orbits gets reduced by 0.3 MeV in this region leading to low-energy states with intruder configuration in ³⁷Si.