New mass measurements of neutron-rich nuclei near N = 20

International audienceThe masses of 39 neutron-rich nuclei in the mass range 17–37 have been measured using a direct time-of-flight technique following the fragmentation of a 48Ca beam at 55 MeV/nucleon. The masses of 29,30Ne, 34,35Mg and 36,37Al are reported for the first time. The very neutron-rich nuclei, 31–33Na, are found to be 2–4 MeV less bound than previously believed. A comparison is made with recently available large scale shell model calculations encompassing the deformed A∼32 nuclei. Conclusions are drawn regarding the extent of the region of deformation, which is found to include 30Ne

Mass measurements of neutron-rich nuclei via fragmentation of 48^{48}Ca beam at 55 MeV/A

International audienc

First observation of the neutron-rich nuclei42Si,45, 46P,48S, and51Cl from the interaction of 44 MeV/u48Ca +64Ni

Five new very neutron-rich isotopes, 42Si,45,46p, 48 S and 51CI, are identiled from the interaction of a 44 MeV/b 48Ca beam with a 64Ni target

Mass measurements of neutron-rich nuclei via fragmentation of 48^{48}Ca beam at 55 MeV/A

International audienc

Shape coexistence and the \mth{N=20} shell closure far from stability by inelastic scattering

Following mass measurements in the region $N=20$ and $N=28$, we have studied inelastic nuclear scattering for the nuclei $^{34}$Si, $^{33}$Al and $^{32}$Mg. No evidence for a low-lying shape isomeric 0$^+$ state was found in $^{34}$Si, and an upper limit for the population cross-section could be established, rendering its existence very unlikely. A new transition was found in $^{33}$Al, that is a good candidate for a 2p-2h state and therefore a determination of the 2p-2h gap at $N=20$. Inelastic nuclear scattering strongly excites 3$^-$ states, as seen in $^{34}$Si. A strong transition was found in $^{32}$Mg that should correspond to the first 3$^-$ in this nucleus, lying very low as compared to theory and systematics in this region