Collisions induced by ${}^{9,10,11}\mathrm{Be}$ on a ${}^{64}\mathrm{Zn}$ target at the same c.m. energy were studied. For the first time, strong effects of the ${}^{11}\mathrm{Be}$ halo structure on elastic-scattering and reaction mechanisms at energies near the Coulomb barrier are evidenced experimentally. The elastic-scattering cross section of the ${}^{11}\mathrm{Be}$ halo nucleus shows unusual behavior in the Coulomb-nuclear interference peak angular region. The extracted total-reaction cross section for the ${}^{11}\mathrm{Be}$ collision is more than double the ones measured in the collisions induced by ${}^{9,10}\mathrm{Be}$. It is shown that such a strong enhancement of the total-reaction cross section with ${}^{11}\mathrm{Be}$ is due to transfer and breakup processes.

We have observed the two-proton radioactivity of the previously unknown ${}^{19}\mathrm{Mg}$ ground state by tracking the decay products in-flight. For the first time, the trajectories of the $2p$-decay products, ${}^{17}\mathrm{Ne}+p+p$, have been measured by using tracking microstrip detectors which allowed us to reconstruct the $2p$-decay vertices and fragment correlations. The half-life of ${}^{19}\mathrm{Mg}$ deduced from the measured vertex distribution is 4.0(15) ps in the system of ${}^{19}\mathrm{Mg}$. The $Q$ value of the $2p$ decay of the ${}^{19}\mathrm{Mg}$ ground state inferred from the measured $p-p-{}^{17}\mathrm{Ne}$ correlations is 0.75(5) MeV.

The elastic scattering of 6He on 208Pb has been measured at laboratory energies of 14, 16, 18 and 22 MeV. These data were analyzed using phenomenological Woods–Saxon form factors and optical model calculations. A semiclassical polarization potential was used to study the effect of the Coulomb dipole polarizability. Evidence for long range absorption, partially arising from Coulomb dipole polarizability, is reported. The energy variation of the optical potential was found to be consistent with the dispersion relations which connect the real and imaginary parts of the potential.status: publishe

The first measurement of the elastic scattering of the halo nucleus ${}^{11}\mathrm{Li}$ and its core ${}^9\mathrm{Li}$ on ${}^{208}\mathrm{Pb}$ at energies near the Coulomb barrier is presented. The ${}^{11}\mathrm{Li}+{}^{208}\mathrm{Pb}$ elastic scattering shows a strong reduction with respect to the Rutherford cross section, even at energies well below the barrier and down to very small scattering angles. This drastic change of the elastic differential cross section observed in ${}^{11}\mathrm{Li}+{}^{208}\mathrm{Pb}$ is the consequence of the halo structure of ${}^{11}\mathrm{Li}$, as it is not observed in the elastic scattering of its core ${}^9\mathrm{Li}$ at the same energies. Four-body continuum-discretized coupled-channels calculations, based on a three-body model of the ${}^{11}\mathrm{Li}$ projectile, are found to explain the measured angular distributions and confirm that the observed reduction is mainly due to the strong Coulomb coupling to the dipole states in the low-lying continuum of ${}^{11}\mathrm{Li}$. These calculations suggest the presence of a low-lying dipole resonance in ${}^{11}\mathrm{Li}$ close to the breakup threshold.

The positron-neutrino correlation in the $0^{+}\to 0^{+}$ $\beta$ decay of ${}^{32}\mathrm{Ar}$ was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the superallowed decay. Our result is consistent with the standard model prediction. For vanishing Fierz interference we find $a=0.9989\mathrm{}\pm 0.0052\pm 0.0039$, which yields improved constraints on scalar weak interactions.