The p((11)Li, (9)Li)t reaction has been studied for the first time at an incident energy of 3A MeV at the new ISAC-2 facility at TRIUMF. An active target detector MAYA, built at GANIL, was used for ...the measurement. The differential cross sections have been determined for transitions to the (9)Li ground and first excited states in a wide range of scattering angles. Multistep transfer calculations using different (11)Li model wave functions show that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.
The low-lying spectroscopy of 6He was investigated via the 2-neutron transfer reaction p (He 8 , t) with the 8He beam delivered by the SPIRAL facility at 15.4 A MeV . The light charged particles ...produced by the direct reactions were measured using the MUST2 Si-strip telescope array. Above the known 2 + state, two new resonances were observed: at E a = 2.6 +/- 0.3 MeV (width Phi = 1.6 +/- 0.4 MeV) and at 5.3 +/- 0.3 MeV with Phi = 2 +/- 1 MeV . Through the analysis of the angular distributions, they correspond to a 2 + state and to an L = 1 state, respectively. These new states, challenging the nuclear theories, could be used as benchmarks for checking the microscopic inputs of the newly improved structure models, and should trigger development of models including the treatments of both core excitation and continuum coupling effects.
The Super-FRS project at GSI Geissel, H.; Weick, H.; Winkler, M. ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms,
05/2003, Letnik:
204
Journal Article, Conference Proceeding
Recenzirano
The GSI projectile fragment separator FRS has demonstrated with many pioneering experiments the research potential of in-flight separators at relativistic energies. Although the present facility has ...contributed much to the progress in the field of nuclear structure physics, major improvements are desirable in the future. The characteristics of the proposed next-generation facility at GSI, the Super-FRS, will be presented and compared to other projects. The Super-FRS is a large-acceptance superconducting fragment separator followed by different experimental branches including a combination with a new storage-cooler ring system. This system consists of a collector ring (CR) and a new experimental storage ring (NESR) which allow precision mass and lifetime measurements as well as in-ring reaction studies. The NESR can be operated in combination with an electron ring to measure electron scattering with exotic nuclei. This electron heavy-ion collider will open up new fields for nuclear structure research.
The N = 28 shell closure has been investigated via the 46Ar(d,p)47Ar transfer reaction in inverse kinematics. Energies and spectroscopic factors of the neutron p(3/2), p(1/2), and f(5/2) states in ...47Ar were determined and compared to those of the 49Ca isotone. We deduced a reduction of the N = 28 gap by 330(90) keV and spin-orbit weakenings of approximately 10(2) and 45(10)% for the f and p states, respectively. Such large variations for the f and p spin-orbit splittings could be accounted for by the proton-neutron tensor force and by the density dependence of the spin-orbit interaction, respectively. This contrasts with the picture of the spin-orbit interaction as a surface term only.
The interaction of exotic nuclei with various targets and implying different types of reactions allows to access a rich variety of information. Some examples of the latest results and recent ...developments related to some of these reactions are reviewed.
In-beam gamma-ray spectroscopy using fragmentation reactions of both stable and radioactive beams has been performed in order to study the structure of excited states in neutron-rich oxygen isotopes ...with masses ranging from A=20 to 24. For the produced fragments, gamma-ray energies, intensities, and gamma-gamma coincidences have been measured. Based on this information new level schemes are proposed for O-21,O-22 up to the neutron separation energy. The nonobservation of any gamma-decay branch from O-23 and O-24 suggests that their excited states lie above the neutron decay thresholds. From this, as well as from the level schemes proposed for O-21 and O-22, the size of the N=14 and 16 shell gaps in oxygen isotopes is discussed in the light of shell-model calculations.
Results from the gamma-ray spectroscopy of {47,48}Ar exemplifying new limits of sensitivity for characterizing neutron-rich nuclei at energies around the Coulomb barrier are presented. The present ...results, along with interacting shell model calculations, highlight the role of cross-shell excitations and indicate the presence of a nonaxial deformation in 48Ar.
By the very nature of secondary beams, their intensity is limited, particularly for beams of the highest interest --farthest away from stability. Active targets, which can be described as time ...projection chamber (TPC)-like detectors in which the detector gas is the target, have been shown to have the highest sensitivity for quantitative high-resolution studies of rare events. The physics cases that can be addressed with these devices are reviewed and some of the first results obtained with first-generation active targets are detailed. Finally some general ideas on the next generation of active targets are presented
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