J.A. Zimmerman

Study of Nuclear Reactions with Intense, High-Purity, Low-Energy Radioactive Ion Beams Using a Versatile Multi-configuration Dual Superconducting-Solenoid System

Abstract A new device (TwinSol) installed at the Nuclear Structure Laboratory at the University of Notre Dame implements a pair of large-bore 6xa0T superconducting solenoids for producing relatively pure, high-intensity beams of exotic light nuclei at low-energies (10–80xa0MeV). Typical beams include 8 Li and 6 He (T 1/2

Nuclear and Coulomb Interaction in 8B Breakup at Sub-Coulomb Energies

The angular distribution for the breakup of 8B-->7Be+p on a 58Ni target has been measured at an incident energy of 25.75 MeV. The data are inconsistent with first-order theories but are remarkably well described by calculations including higher-order effects. The comparison with theory illustrates the importance of the inclusion of the exotic proton halo structure of 8B in accounting for the data.

Nuclear and Coulomb Interaction in the 8B to 7Be + p Breakup Reaction at sub-Coulomb Energies

The angular distribution for the breakup of 8B-->7Be+p on a 58Ni target has been measured at an incident energy of 25.75 MeV. The data are inconsistent with first-order theories but are remarkably well described by calculations including higher-order effects. The comparison with theory illustrates the importance of the inclusion of the exotic proton halo structure of 8B in accounting for the data.

REACTION CROSS SECTIONS IN SI OF LIGHT PROTON-HALO CANDIDATES 12N AND 17NE

Abstract Total reaction cross sections, σ R , on Si were measured near 40 A MeV for the proton-halo candidate 12 N and the two-proton-halo candidate 17 Ne, and were compared with σ R for other light proton-rich nuclei. The A -dependence shows enhanced σ R s for 12 N and 17 Ne, relative to their neighbors, but the effect is smaller than for 8 B which has been argued to have a proton halo. In general, nuclei with loosely bound last protons ( S p ⩽ 1.5 MeV) have significantly larger σ R s than their neighbors. Cross sections for charge-removal from 12 N and 17 Ne also were obtained.

Gamma-ray spectroscopy with a low-energy 6He radioactive ion beam

Abstract A gamma-ray spectroscopy program has been established at the University of Notre Dame using a low-energy radioactive beam of 6 He for fusion–evaporation reactions. There are many experimental difficulties to overcome in the design of any such facility, most notably the large neutron flux associated with producing the secondary beam. Solutions to the problems are discussed and illustrated with the reaction 6 He + 63 Cu .

A dual 6T persistent-mode SC solenoid ion-optical system for radioactive nuclear beam research

A unique ion-optical system for the production of high-intensity, short-lived radioactive nuclear beams has been designed, constructed and put into operation at the Nuclear Structure Laboratory at the University of Notre Dame as a joint project between the University of Michigan and NSL-UND. The system consists of a matched in-line pair of large-bore (30 cm) 6T superconductive solenoid magnets which act as high-acceptance collectors and magnetic filters of secondary radioactive nuclear beam (RNB) products. The latter are brought to a focus on a secondary target and nuclear reactions using the RNB studied. These are primarily reactions of interest in Big-Bang nucleosynthesis and stellar helium burning and involve the production of /sup 6/He, /sup 7/Be, /sup 8/B and similar beams. A number of unique features were incorporated in the magnet design to permit use as a precise ion-optical device in the RNB mode. To the authors knowledge this is the only large-scale in-beam ion-optical system to operate primarily in persistent mode. A similar device will also be built at the University of Sao Paulo for RNB research.

Twinsol: A dual superconducting solenoid system for low-energy radioactive nuclear beam research

A unique type of apparatus is currently under construction as part of an upgrade to the radioactive ion beam facility at the University of Notre Dame Nuclear Structure Laboratory. The device will consist of a pair of large in-line superconducting solenoids (B0=6u2009tesla, bore=30u2009cm) which will be used to produce, collect, transport, focus and analyze both stable and radioactive nuclear beams. This apparatus in conjunction with the recently upgraded accelerators at Notre Dame is especially well suited for the production and utilization of intense (viz. >106/sec), low-energy (1–10 MeV/u), stable and radioactive nuclear beams relevant to the study of reactions involved in astrophysical processes. These improvements will allow for the production of radioactive beams of greater intensity, higher purity and at both higher and lower energies than previously available at this facility. The first phase of construction and results of initial tests will be reported.