Measurement of 238Np fission cross-section by neutrons near thermal point (preliminary results)

Isomeric 0− halo-states in 12Be and 11Li

“…For 16 N and 16 F, for which some of the states should correspond to one neutron and one proton in the sp-levels, the spectra also present the same 0 − -, 1 − -states at (0.12 MeV, 0.40 MeV) and (ground state, 0.19 MeV). The 0 − is close but below the 1 − -state, as repeated in 14 N but with larger spacing.…”

“…In particular, when one of the neutrons is in the s 1/2 -shell and the other one in the p 1/2 -shell, this structure can obviously lead to either a 1 − or a 0 − excited state. This doublet can actually be found for instance in 14 C with excitation energies of 6.09 MeV and 6.90 MeV, respectively [17], and in 16 O with excitation energies of 9.59 MeV and 10.97 MeV, respectively [18]. A linear extrapolation in mass from 16 O over 14 C to 12 Be and 11 Li leads to predictions of (2.8 MeV, 2.6 MeV) and (0.80 MeV, 0.84 MeV) for 12 Be and 11 Li, respectively, for 0 − and 1 − .…”

“…For 9 neutrons different ground state spins, 5/2 + and 1/2 + , are also found for 17 O and 15 C. For the particle unstable nucleus 10 Li different theoretical works predicted the existence of a similar low-lying s-wave intruder state [9][10][11], in such a way that the ground state in 10 Li should correspond to a state with negative parity (the ground state of 9 Li has spin and parity 3/2 − ). The available experimental data concerning the ground state properties of 10 Li are however controversial, although most of them point towards the existence of such a low-lying virtual s-state [12][13][14][15]. This result has also been recently supported in [16].…”