Intruder negative-parity states of neutron-richSi33

Abstract

Yrast states in the neutron-rich 33 14 Si 19 nucleus have been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of 36 S ions with a thin 208 Pb target. An experimental setup that combines the large-acceptance magnetic spectrometer PRISMA and the high-efficiency γ -ray detection array CLARA was used in the experiment. Four new γ -ray photopeaks at energies of 971, 1724, 1772, and 2655 keV were observed and assigned to the 33 Si level scheme. The experimental level scheme is compared with the results of 1hω p-sd-pf large-scale shell-model calculations using the recently developed PSDPFB effective interaction; good agreement is obtained. The structure of the populated states of 33 Si is discussed within the context of an odd neutron coupled to states of the 32 Si core.

Structure of Si33 and the magicity of the N=20 gap at Z=14Jongile1, Lemasson2, Sorlin3 et al. 2020Phys. Rev. CSelf Cite10030View full textAdd to dashboardCite

“…As shown in the inset of Fig 2, the 931 keV transition is observed in coincidence with the 1724 keV transition, which establishes that the (11/2 − 1 ) state at 4090 keV decays both to the (9/2 − ) state at 3159 keV and to the previously observed 10.2 ns isomeric (7/2 − ) state with an energy of 2655 keV [20]. This new information on the competing decay branches strengthens the earlier, tentative assignment of (11/2 − 1 ) for the state [20]. A doublet of states is observed at 4268 and 4347 keV, of which the 4268 keV transition is observed for the first time.…”

“…Prior to the present work, the knockout residue 33 Si was studied using a variety of experimental techniques, e.g. multi-nucleon transfer [18], β-decay [19], thick-target deep-inelastic reactions [20], and a one-neutron knockout reaction [21]. The work of Fifield et al [18] led to the identification of excited states at 1.47, 2.0, 3.19, 4.13 and 5.48 MeV with an uncertainty of about 40 keV, but without spin assignments.…”

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“…The neutron-rich S, P and Si nuclei have been populated using the 36 S on 208 Pb reaction. The excited structures of 40 S [9], 33 Si [10] and 38 Cl [11] have been investigated at medium and high spin and compared with the results of large scale 1 ω p-sd-pf shell model calculations. The results have been used in order to validate the predictions of different residual interaction including in particular the recently developed PSDPFB effective interaction.…”

Spectroscopy of neutron-richP34,35,36,37,38populated in binary grazing reactions

“…The present work forms one of several studies of neutronrich nuclei in the sdpf shell, which are based on results from the same experiment. To date, we have reported on the structure of 36 Si [20], 37 P [5], 40 S [22], 38 Cl [23], 33 Si [24], and 41 S [25]. Earlier related studies of neutron-rich nuclei populated in deep-inelastic collisions with thick targets have focused on the structure of 34 P [26], 36 S [27], and 41 Cl [10,28].…”