Spectroscopy Near the N=20 Shell Closure: β-n Decay Studies of 33Mg and 35Al

Multiparticle-multihole states in31Mg and33Mg: A critical evaluation

“…The β decay of 33 Mg, produced by projectile fragmentation, has been studied at GANIL [41] and at MSU [33]. The published decay schemes as well as the conclusions are somewhat different.…”

“…In both studies, only levels above 1.6 MeV have been populated in the N = 20 isotope 33 Al. The major difference between both decay schemes is the strong feeding of a level at 1647 keV in [41], while most of this intensity is included in the 37(8)% missing intensity, attributed to the g.s. feeding in [33].…”

Normal and intruder configurations in Si34 populated in the β− decay of Mg34Lică1, Rotaru2, Borge3 et al. 2019Phys. Rev. C13170View full textAdd to dashboardCite

“…high 2 + energy [12], low B(E2; 2 + 1 → 0 + 1 ) value [18], drop in S n value after N = 20), but lies at the verge of the 'Island of Inversion', where nuclei are deformed in their ground state configuration. It follows that deformed configurations, shape coexistence [19] and possibly triaxial shapes are present already among the few first excited states in 34 Si [20]. The abrupt transition from the closedshell ground-state of 34 Si to the intruder-dominated deformed ground state of 32 Mg [21], while removing only two protons in the 1d 5/2 orbit, is a challenge for nuclear models [22,23].…”

“…This is due to the delicate balance between the amplitude of the proton and neutron shell gaps that prevents nuclear excitations, and the large correlation energy that are maximum when many particle-hole excitations across these gaps are present. A central proton density depletion, so-called 'bubble', [24] was recently identified in 34 Si, one of the few nuclei that experience a drastic reduction of its spin-orbit interaction (for L = 1 neutrons), as compared to the neighboring nuclei. 34 Si was recently studied at GANIL [19] through the β-decay of 34 Al produced in the 'one neutron pick-up and three proton removal' reaction channel using a 36 S beam at intermediate energy (77.5 MeV/A).…”

“…A central proton density depletion, so-called 'bubble', [24] was recently identified in 34 Si, one of the few nuclei that experience a drastic reduction of its spin-orbit interaction (for L = 1 neutrons), as compared to the neighboring nuclei. 34 Si was recently studied at GANIL [19] through the β-decay of 34 Al produced in the 'one neutron pick-up and three proton removal' reaction channel using a 36 S beam at intermediate energy (77.5 MeV/A). Through electron-positron pairs energy measurements, the authors identified the 0 + 2 state in 34 Si at 2.7 MeV excitation energy, with a half-life of T 1/2 = 19.3 (7) ns and also determined the reduced monopole transition strength ρ 2 (E0, 0 + 2 → 0 + 1 ) = 13(1) × 10 −3 .…”