Search

The investigation of the limits of nuclear existence is fundamental to the understanding of nuclear forces and structure. The limits of binding for very neutron-rich nuclei and the location of the neutron dripline are established experimentally only for the lightest elements. We report on the discovery of the new neutron-rich isotopes 40Mg, 42,43Al, and 44Si. These rare isotopes were produced at the National Superconducting Cyclotron Laboratory by fragmentation of a 141 MeV/u 48Ca beam on a tungsten target. The combination of the A1900 fragment separator together with the analysis beam line of the S800 spectrograph provided a two-stage fragment separation with exceptional selectivity. The observation of the odd-odd nucleus 42Al, which was predicted to be unbound by FRDM [1] and HFB-8 [2] models, is the first indication that the neutron drip line may be located significantly further towards heavier isotopes in this mass region than it is currently believed. [ABSTRACT FROM AUTHOR]

The Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory at Michigan State University provides a large variety of new isotopes previously inaccessible and others at rates sufficienct for in-beam spectroscopy. This talk presents some of our recent results elucidating the structure of exotic nuclei. After a general overview of scientific highlights from the first two years of operation particular results from several in-beam gamma-ray spectroscopy experiments in the vicinities of neutron numbers N=16, N=20, N=28 in the π(sd) shell around 56Ni will be discussed. Inelastic scattering experiments with gamma-ray detection on light and heavy targets have determined specific transition matrix elements and excited state energies. One- and two-particle nucleon knockout reactions were used to investigate the wave functions of specific states and to deduce corresponding spectroscopic factors. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The width of the Giant Dipole Resonance in Sn was studied by means of inelastic scattering. This study allowed for the first measurement of the GDR width at a temperature of 1 MeV. The width was found to be 4±1 MeV, and is consistent with the ground state measurement. This result is in disagreement with adiabatic thermal shape fluctuation calculations, indicating an overestimation of the influence of thermal shape fluctuations at low temperature. [ABSTRACT FROM AUTHOR]

The masses of very neutron-deficient [sup 66]As, [sup 68,70,71]Se and [sup 71]Br were measured for the first time and those of [sup 64,65]Ge and [sup 67]As remeasured, with total uncertainties ranging from 200 to 1000 keV, including systematic, extrapolation and statistical errors, using the SPEG direct time-of-flight method at GANIL. These new results are discussed and compared to other recent experimental data and mass predictions. [ABSTRACT FROM AUTHOR]

This paper outlines the role of the Isospin Laboratory Steering Committee in the process that has lead to our current understand of the possibilities and challenges related to an advance rare isotope research facility. One of the challenges is to extract information using only weak rare isotope beams. Knock-out reactions are used as an example to illustrate that access to even weak beams can provide a large amount of nuclear structure information. [ABSTRACT FROM AUTHOR]

The momentum distributions of the residual nuclei after one-neutron removal, measured in coincidence with gamma rays, identify the excited levels of these residues. The resulting differential partial cross sections map the momentum content and structure of the removed-nucleon wave function and provide an exacting test of theory. Data for population of the [sup 14]C and [sup 10]Be ground states show an asymmetry that is incompatible with the currently used eikonal descriptions. A fully dynamical description of the elastic breakup mechanism provides an understanding of the new observation, which will be most pronounced for nuclear halo states. This interpretation is clarified by an analysis of the angular distribution of the heavy residues. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The NSCL has recently completed the Coupled Cyclotron Facility, which provides higher energy and higher intensity beams for studies of nuclear reactions and nuclear structure. Central to this project was the replacement of the A1200 fragment separator with a new high acceptance device called the A1900. The new fragment separator connects the upgraded cyclotrons with the existing beam lines and provides and order of magnitude higher collection efficiency compared to the ols A1200. Parameters of the A1900 are described and results from the commissioning experiments are reported. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]