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Experimental information on fragment emissions is important in understanding the dynamics of nuclear collisions and in the development of transport model simulating heavy-ion collisions. The composition of complex fragments emitted in the heavy-ion collisions can be explained by statistical models, which assume that thermal equilibrium is achieved at collision energies below 100 MeV/u. Our new experimental data together with theoretical analyses for light particles from Sn+Sn collisions at 270 MeV/u, suggest that the hypothesis of thermal equilibrium breaks down for particles emitted with high transfer momentum. To inspect the system's properties in such limit, the scaling features of the yield ratios of particles from two systems, a neutron-rich system of ${}^{132}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ and a nearly symmetric system of ${}^{108}\mathrm{Sn}+{}^{112}\mathrm{Sn}$, are examined in the framework of the statistical multifragmentation model and the antisymmetrized molecular dynamics model. The isoscaling from low energy particles agree with both models. However the observed breakdown of isoscaling for particles with high transverse momentum cannot be explained by the antisymmetrized molecular dynamics model.

This work demonstrates the feasibility of in-beam γ-spectroscopy employing radioactive ion beam species at relativistic energies of E = 210 ∼ 280 A· MeV. Neutron-rich nuclei below 48Ca with neutron number between the two magic numbers 20 and 28 have been investigated. Using a Pb target, single step inelastic excitation originating mainly from Coulomb interaction takes place populating preferentially low-lying low-spin states and enabling the extraction of B(E2) values. On a C target, nucleon removal reactions are dominating and medium-spin states are populated thus offering spectroscopic information in neighboring nuclei. Cross sections of inelastic excitation are determined and compared to coupled-channels calculations. Two new states of the very neutron-rich nucleus 44Ar at 1.78(8) MeV and 2.61(16) MeV are deduced from γ-transitions.

Coulomb breakup of neutron-rich Be, B, C, and O isotopes at relativistic energies (400–600 A MeV) was studied with kinematically complete measurements. The ground-state properties of these nuclei were deduced by comparing experimental data for Coulomb-dissociation cross-sections with directbreakup model calculations. The dominant ground-state configurations of 15C, 11Be, 14B, and 23O were found to be 14Cgs(0+) ⊗ v s, 10Begs(0+) ⊗ v s, 13Bgs(3/2+) ⊗ v s,d, and 22Ogs(0+) ⊗ v s, respectively, and 16C(2+) ⊗ v s,d, for 17C. The capture cross-section for 14C(n,λ) 15C relevant in astrophysical scenarios was measured indirectly through Coulomb dissociation.

Results are presented from a one-neutron knockout experiment at relativistic energies of $ \approx 420 A$ MeV on 51-55Sc using the GSI Fragment Separator as a two-stage magnetic spectrometer and the MINIBALL array for gamma-ray detection. Inclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the contributions corresponding to knockout from the $ \nu p_{1/2}$ , $ \nu p_{3/2}$ , (L = 1 and $ \nu f_{7/2}$ , $ \nu f_{5/2}$ (L = 3 neutron orbitals. The observed L = 1 and L = 3 contributions are compared with theoretical cross-sections using eikonal knockout theory and spectroscopic factors from shell model calculations using the GXPF1A interaction. The measured inclusive knockout cross-sections generally follow the trends expected theoretically and given by the spectroscopic strength predicted from the shell model calculations. However, the deduced L = 1 cross-sections are generally 30-40% higher while the L = 3 contributions are about a factor of two smaller than predicted. This points to a promotion of neutrons from the $ \nu f_{7/2}$ to the $ \nu p_{3/2}$ orbital indicating a weakening of the N = 28 shell gap in these nuclei. While this is not predicted for the phenomenological GXPF1A interaction such a weakening is predicted by recent calculations using realistic low-momentum interactions $ V_{low k}$ obtained by evolving a chiral N3LO nucleon-nucleon potential.