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Nucleon knockout experiments using beryllium or carbon targets reveal a strong dependence of the quenching factors, i.e., the ratio ( R s ) of theoretical to the experimental spectroscopic factors ( C 2 S ), on the proton-neutron asymmetry in the nucleus under study. However, this dependence is greatly reduced when a hydrogen target is used. To understand this phenomenon, exclusive 1 H (17 Ne , 2 p 16 F) and inclusive 12 C (17 Ne , 2 p 16 F) X , 12 C (17 Ne , 16 F) X as well as 1 H (17 Ne , 16 F) X (X-denotes undetected reaction products) reactions with 16 F in the ground and excited states were analysed. The longitudinal momentum distribution of 16 F and the correlations between the detached protons were studied. In the case of the carbon target, there is a significant deviation from the predictions of the eikonal model. The eikonal approximation was used to extract spectroscopic factor values C 2 S . The experimental C 2 S value obtained with C target is markedly lower than that for H target. This is interpreted as rescattering due to simultaneous nucleon knockout from both reaction partners, 17 Ne and 12 C . [ABSTRACT FROM AUTHOR]

The matter radius of the doubly magic 56 Ni was extracted from a measurement of the differential cross section by employing, for the first time, elastic proton scattering in inverse kinematics with a radioactive beam at E kin = 390.2 MeV/nucleon circulating in a storage ring and passing an internal hydrogen gas-jet target with a revolution frequency of around 2 MHz. The novel experimental scheme is based on UHV-compatible Si detectors operated as active vacuum windows, which were implemented in the ESR storage ring at GSI. A matter radius < r m 2 > 1 / 2 = 3. 74 - 0.06 + 0.03 fm was extracted for the doubly-magic self-conjugate nucleus 56 Ni. [ABSTRACT FROM AUTHOR]

We present the design, prototype developments and test results of the new time-of-flight detector (ToFD) which is part of the R 3 B experimental setup at GSI and FAIR, Darmstadt, Germany. The ToFD detector is able to detect heavy-ion residues of all charges at relativistic energies with a relative energy precision σ Δ E / Δ E of up to 1% and a time precision of up to 14 ps (sigma). Together with an elaborate particle-tracking system, the full identification of relativistic ions from hydrogen up to uranium in mass and nuclear charge is possible. [ABSTRACT FROM AUTHOR]

We investigate the contributions of various reaction channels to the interaction, reaction, charge-changing and neutron-changing cross sections. The goal is to investigate the relation between microscopic interactions and the symmetry energy component of the equation of state (EoS) of interest for the structure of neutron stars. We compare the neutron skins extracted from diverse experimental techniques with those obtained with Hartree–Fock–Bogoliubov calculations using 23 Skyrme and with eight density-dependent interactions used in the relativistic mean-field method. We show that no particular conclusion can be drawn on the best EoS in view of the wide range of uncertainty in the experimental data. We further investigate the prospects of using neutron-changing reactions to assess the isospin dependence of the neutron skin in neutron-rich nuclei. [ABSTRACT FROM AUTHOR]

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 Sn + 124 Sn and a nearly symmetric system of 108 Sn + 112 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. [ABSTRACT FROM AUTHOR]

PUMA, antiProton Unstable Matter Annihilation, is a nuclear-physics experiment at CERN aiming at probing the surface properties of stable and rare isotopes by use of low-energy antiprotons. Low-energy antiprotons offer a very unique sensitivity to the neutron and proton densities at the annihilation site, i.e. in the tail of the nuclear density. Today, no facility provides a collider of low-energy radioactive ions and low-energy antiprotons: while not being a collider experiment, PUMA aims at transporting one billion antiprotons from ELENA, the Extra-Low-ENergy Antiproton ring, to ISOLDE, the rare-isotope beam facility of CERN. PUMA will enable the capture of low-energy antiprotons by short-lived nuclei and the measurement of the emitted radiations. In this way, PUMA will give access to the so-far largely unexplored isospin composition of the nuclear-radial-density tail of radioactive nuclei. The motivations, concept and current status of the PUMA experiment are presented. [ABSTRACT FROM AUTHOR]

Quasi-free scattering of electrons and protons has been extensively utilized in the past to study the single-particle structure of nuclei, clustering in light nuclei, and short-range correlated nucleon–nucleon pairs in nuclei. Recently, this approach has been applied in inverse kinematics using hydrogen targets. The characteristic features of this reaction and the experimental challenges and advantages of inverse-kinematics experiments are summarized. The applicability to radioactive beams opens a large research potential to study a variety of properties of neutron-to-proton asymmetric nuclei. Applications of quasi-free scattering in inverse kinematics and its potential are reviewed based on recent and ongoing research programs at different accelerator facilities worldwide. [ABSTRACT FROM AUTHOR]

The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N = 8 shell gap for neutron-rich systems like 11Li and 12Be, or the new closed N = 14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei, in particular, show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. [ABSTRACT FROM AUTHOR]

Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope 23O. The 22O fragments produced in one-nucleon removal from 23O at 938 MeV/nucleon in a carbon target were detected in coincidence with de-exciting γ rays, allowing to discern between 22O ground-state and excited-states contributions. From the comparison of exclusive experimental momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated in an Eikonal model for the knockout process, and spin and parity assignment of Iπ = 1/2+ was deduced for the 23O ground state. This result solved the existent experimental discrepancy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 direct-breakup model calculations. The dominant ground-state configurations of 15C, 11Be, 14B, and 23O were found to be 14C gs(0+) ⊗ νs,10Be gs(0+) ⊗ νs, 13B gs(3/2+) ⊗ νs,d, and 22O gs(0+) ⊗ νs, respectively, and 16C(2 +) ⊗ νs,d for 17C. The capture cross-section for 14C(n,γ) 15C relevant in astrophysical scenarios was measured indirectly through Coulomb dissociation. [ABSTRACT FROM AUTHOR]