Mixing between single-particle and intruder configurations towards the N=20 Island of Inversion: Lifetime measurements in
Le résumé fourni par la source
The disappearance of the N=20 shell closure, the so-called “island of inversion”, around 32Mg is one of the most striking examples of the strength of nucleon-nucleon correlations. In this region, the quadrupole-deformed intruder configuration (based on a multi-particle multi-hole configuration) becomes the ground state, subverting the expected shell ordering predicted by a harmonic oscillator plus spin-orbit term. The full mapping of the structural evolution leading to the emergence of the island represents an important benchmark for nuclear structure models attempting to reproduce the physics of this region. In this context, lifetime measurements of excited states are important observables, since they are related to electromagnetic transition matrix elements and therefore contain information on the microscopic structure of the states involved. The coupling of the state-of-the-art AGATA spectrometer with a light charged-particle detector in an experiment at INFN Legnaro National Laboratories allowed the measurement of nuclear lifetimes in the femtosecond and picosecond range in 37S. In this nucleus, strong branching ratios between single-particle and intruder states suggest that these configurations mix significantly, contrary to the notion that 37S is well out of the island of inversion. The results of this experiment, employing a high-resolution and state-of-the-art setup, will provide a precise quantification of this phenomenon in terms of transition strengths.
Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.