Search

The spectroscopic quadrupole moment of the high-spin, high- K five-quasiparticle isomer (K(pi) = 35/2(-), T(1/2) = 750(80) ns, E(i) = 3349 keV) in (179)W has been determined using the level mixing spectroscopy method. A value Q(s) = 4.00(+0.83-1.06)e b was derived, which corresponds to an intrinsic quadrupole moment Q0 = 4.73(+0.98-1.25)e b and to a quadrupole deformation beta(2) = 0.185(+0.038-0.049). These values differ significantly from the deduced ground-state quadrupole moments and are in disagreement with the current theoretical predictions in this mass region.

The ground state of the proton-rich, unbound nucleus ${}^{11}\mathrm{N}$ was observed, together with six excited states using the multinucleon transfer reaction ${}^{10}\mathrm{B}{(}^{14}\mathrm{N}{,}^{13}\mathrm{B}{)}^{11}\mathrm{N}$ at $30A$ MeV incident energy at Grand Acc\'el\'erateur National d'Ions Lourds. Levels of ${}^{11}\mathrm{N}$ are observed as well defined resonances in the spectrum of the ${}^{13}\mathrm{B}$ ejectiles. They are localized at 1.63(5), 2.16(5), 3.06(8), 3.61(5), 4.33(5), 5.98(10), and 6.54(10) MeV above the ${}^{10}\mathrm{C}+p$ threshold. The ground-state resonance has a mass excess of 24.618(50) MeV; the experimental width is smaller than theoretical predictions.

In a high precision experiment, Mott scattering of the [sup 208]Pb+[sup 108]Pb system was measured at [ital E][sub lab]=873.40 MeV and 1129.74 MeV with kinematic coincidences for angle pairs around [theta][sub lab]=30[degree], 60[degree] and [theta][sub lab]=45[degree], 45[degree]. The observed Mott oscillations exhibit an angular shift with respect to pure Mott scattering. A comparison with the angular shift produced by a color van der Waals force including nuclear polarizability, vacuum polarization, relativistic effects, and electronic screening provides a new upper limit for the strength of this force. Influence of atomic effects other than screening were identified for the first time.

A multistep $\ensuremath{\alpha}$-particle-transfer picture is used to describe anomalous back-angle elastic scattering of $^{16}\mathrm{O}$+$^{28}\mathrm{Si}$. Transfer of two and three $\ensuremath{\alpha}$ particles is described in a semiclassical treatment of the interplay between absorption and transfer processes. The energy dependence of the anomalous contribution to the elastic $S$ matrix due to these processes is estimated and shown to be consistent with the overall trend of the data.