Jeff Blackmon

Direct reaction measurements with a 132Sn radioactive ion beam

The (d,p) neutron transfer and (d,d) elastic scattering reactions were measured in inverse kinematics using a radioactive ion beam of {sup 132}Sn at 630 MeV. The elastic scattering data were taken in a region where Rutherford scattering dominated the reaction, and nuclear effects account for less than 8% of the elastic scattering cross section. The magnitude of the nuclear effects, in the angular range studied, was found to be independent of the optical potential used, allowing the transfer data to be normalized in a reliable manner. The neutron-transfer reaction populated a previously unmeasured state at 1363 keV, which is most likely the single-particle 3p{sub 1/2} state expected above the N=82 shell closure. The data were analyzed using finite-range adiabatic-wave calculations and the results compared with the previous analysis using the distorted-wave Born approximation. Angular distributions for the ground and first-excited states are consistent with the previous tentative spin and parity assignments. Spectroscopic factors extracted from the differential cross sections are similar to those found for the one-neutron states beyond the benchmark doubly magic nucleus {sup 208}Pb.

Design of a New Recoil Separator for Measurements of Radiative Capture Reactions in Astrophysics

The rates of proton‐ and alpha‐capture reactions on unstable proton‐rich nuclei are needed to understand the energy generation and element synthesis occurring in novae, X‐ray bursts, and other explosions. Direct measurements of the cross sections of some of these reactions are now possible with radioactive beams and a recoil separator. A new device for such measurements, the Separator for CApture Reactions [SECAR], is being designed for use at the Facility for Rare Isotope Beams (FRIB). The specifications and preliminary conceptual design will be discussed along with plans for the first set of measurements.

Development of a Versatile Array of Neutron Detectors at Low Energy

The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new array of plastic scintillator bars under development for measurements at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The array is highly modular allowing the configuration of the individual elements to be optimized for particular experimental requirements, such as (d,n) and beta‐delayed neutron‐decay measurements with neutron‐rich rare isotope beams.

Recent Nuclear Astrophysics Measurements using the TwinSol Separator

Many astrophysical events, such as novae and X-ray bursts, are powered by reactions with radioactive nuclei. Studying the properties of these nuclei in the laboratory can therefore further our understanding of these astrophysical explosions. The TwinSol separator at the University of Notre Dame has recently been used to produce intense (~106 pps) beams of 17F. In this article, some of the first measurements with these beams are discussed.