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Unstable 10C nuclei are produced as quasi-projectiles in 12C+24Mg collisions at E/A = 53 and 95 MeV. The decay of their short-lived states is studied with the INDRA multidetector array via multi-particle correlation functions. The obtained results show that heavy-ion collisions can be used as a tool to access spectroscopic information of unbound states in exotic nuclei, such as their energies and the relative importance of different sequential decay widths.
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A new procedure to prepare isomerically clean samples of ions with a mass resolving power of more than 100,000 has been developed at the JYFLTRAP tandem Penning trap system. The method utilises a dipolar rf-excitation of the ion motion with separated oscillatory fields in the precision trap. During a subsequent retransfer to the purification trap, the contaminants are rejected and as a consequence, the remaining bunch is isomerically cleaned. This newly-developed method is suitable for very high-resolution cleaning and is at least a factor of five faster than the methods used so far in Penning trap mass spectrometry.
We present the first laser spectroscopic measurement of the neutron-rich nucleus $^{68}$Ni at the mbox{$N=40$} subshell closure and extract its nuclear charge radius. Since this is the only short-lived isotope for which the dipole polarizability $alpha_{rm D}$ has been measured, the combination of these observables provides a benchmark for nuclear structure theory. We compare them to novel coupled-cluster calculations based on different chiral two- and three-nucleon interactions, for which a strong correlation between the charge radius and dipole polarizability is observed, similar to the stable nucleus $^{48}$Ca. Three-particle--three-hole correlations in coupled-cluster theory substantially improve the description of the experimental data, which allows to constrain the neutron radius and neutron skin of $^{68}$Ni.
A beta-ray detecting nuclear quadrupole resonance system has been developed at NSCL/MSU to measure ground-state electric quadrupole moments of short-lived nuclei produced as fast rare isotope beams. This system enables quick and sequential application of multiple transition frequencies over a wide range. Fast switching between variable capacitors in resonance circuits ensures sufficient power delivery to the coil in the beta-ray detecting nuclear magnetic resonance technique. The fast switching technique enhances detection efficiency of resonance signals and is especially useful when the polarization and/or production rate of the nucleus of interest are small and when the nuclear spin is large.
The ratios of inclusive electron scattering cross sections of He4, C12 and Fe56 to He3 have been measured at 1 < x_B < 3. At Q^2 > 1.4 GeV^2, the ratios exhibit two separate plateaus, at 1.5 < x_B < 2 and at x_B > 2.25. This pattern is predicted by models that include 2- and 3-nucleon short-range correlations (SRC). Relative to A=3, the per-nucleon probabilities of 3-nucleon SRC are 2.3, 3.2, and 4.6 times larger for A=4, 12 and 56. This is the first measurement of 3-nucleon SRC probabilities in nuclei.
A theoretical approach was developed to describe secondary particle emission in heavy ion collisions, with special regards to pre-equilibrium {alpha}-particle production. Griffins model of non-equilibrium processes is used to account for the first stage of the compound system formation, while a Monte Carlo statistical approach was used to describe the further decay from a hot source at thermal equilibrium. The probabilities of neutron, proton and {alpha}-particle emission have been evaluated for both the equilibrium and pre-equilibrium stages of the process. Fission and {gamma}-ray emission competition were also considered after equilibration. Effects due the possible cluster structure of the projectile which has been excited during the collisions have been experimentally evidenced studying the double differential cross sections of p and {alpha}-particles emitted in the E=250MeV 16O +116Sn reaction. Calculations within the present model with different clusterization probabilities have been compared to the experimental data.
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