The SNO+ experiment

Abstract

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Low-Energy Coulomb Excitation for the Shell Model

“…The obtained B(E2) values hint at the importance of triaxiality also in neutron-rich Zn isotopes, whose ground states were suggested to be rather diffuse in the γ degree of freedom [42]. Furthermore, the energy of the first excited state in 80 Zn confirms the persistence of the N = 50 shell closure two protons away from the doubly-magic 78 Ni. The same conclusion was reached for the neutron-rich Ge isotopes from the B(E2; 2 + 1 → 0 + g.s ) values of the radioactive 78,80 Ge measured using low-energy Coulomb excitation at ORNL [44].…”

“…Effective charges significantly different from the standard e ν = 0.5e, e π = 1.5e values were adopted to compensate for the enhanced 56 Ni core polarization reported in [46,47]. The persistence of the N = 50 shell closure in neutron-rich Zn and Ge isotopes, emerging from the experimental and calculated B(E2) values and excitation energies, anticipated the more recent results for 78 Ni , in which the first excited 2 + 1 state was ultimately identified [48].…”

“…However, only for 68 Zn has the key 2 + 3 E2 0 + 2 matrix element been determined, which, when combined with other matrix elements involving the 0 + 2 state, leads to a Q 2 invariant significantly different from that of the ground state [28]. On the other hand, multiple lowenergy Coulomb-excitation studies of stable Ge and Zn isotopes [14,25,28] demonstrated the importance of the triaxial degree of freedom in their structure, which was also evoked for the neighbouring 76,78 Se nuclei [29,30]. Particularly relevant is the study of 76 Ge [31], which yielded (β 2 , γ) parameters for the 0 + 1 , 2 + 1 and 2 + 2 states and their dispersions, which are consistent with rigid triaxial deformation.…”

“…On the neutron-rich side, low-energy Coulomb excitation has provided valuable structure information in the Ge and Zn isotopes. Experiments at ISOLDE identified the first excited 2 + 1 state in 78,80 Zn and yielded the B(E2; 2 + 1 → 0 + g.s ) values in [74][75][76][77][78][79][80] Zn and the B(E2; 4 + 1 → 2 + 1 ) values in 74,76 Zn [42,43]. The obtained B(E2) values hint at the importance of triaxiality also in neutron-rich Zn isotopes, whose ground states were suggested to be rather diffuse in the γ degree of freedom [42].…”

“…The measured B(E2; 2 + 1 → 0 + 1 ) values in [74][75][76][77][78][79][80] Zn were found in good agreement with those deduced from the experimental 2 + 1 excitation energies via the Grodzins rule [45], provided that a renormalization factor (0.92) was applied to the calculated values [42]. The experimental results for [74][75][76][77][78][79][80] Zn and 78,80 Ge were compared with Shell-Model calculations comprising the 2p 3/2 , 1 f 5/2 , 2p 1/2 , and 1g 9/2 orbitals for both protons and neutrons outside of an inert 56 Ni core. Effective charges significantly different from the standard e ν = 0.5e, e π = 1.5e values were adopted to compensate for the enhanced 56 Ni core polarization reported in [46,47].…”