A.D. Roberts

Performance of a polarized-hydrogen storage cell target

Abstract A storage cell has been constructed for use as an internal polarized gas target in the storage ring at the Indiana University Cyclotron Facility. The storage cell has thin teflon walls which allow for detection of low energy recoil particles. We report on nuclear polarization measurements of hydrogen atoms, produced by an atomic beam source, in this storage cell. The results indicate that a target polarization in excess of 0.70 is achieved. We discuss the design and construction details of a storage cell target and the polarization results which are based on low-energy pp spin correlation measurements using the University of Wisconsin tandem accelerator.

The Use of a Gas-Filled-Magnet in Experiments with Radioactive Ion Beams

Abstract A detection system has been developed for experiments with radioactive beams which have considerable contamination from a stable isobar. The system uses the gas-filled magnet technique and identifies reaction products according to nuclear charge and mass with good resolution even at energies below 1 MeV/u. In a first experiment the device has been used to measure cross sections for the 18F(p, α)15O reaction in the energy range between 650 and 840 keV/u.

Nuclear Reactions Studies with Radioactive 18F Beams at ATLAS

Abstract The contribution of the 18 F(p,γ) reaction to the production of 19 Ne which is the crucial isotope for the breakout from the hot CNO cycle into the rp process, has been investigated in experiments with 18 F beams. Measurements of the cross sections for the 18 F(p,α) 15 O and the 18 F(p,γ) 19 Ne reactions indicate that the contribution from the (p,γ) route to the formation of 19 Ne is small.

The influence of 18F induced reactions in the hot CNO cycle

Abstract The contribution of the 18 F(p,γ) reaction to the production of 19 Ne, which is an important isotope in connection with the breakout from the hot CNO cycle, has been investigated in experiments with 18 F beams. Measurements of the cross sections for the 18 F(p,α) 15 O and 18 F(p,γ) 19 Ne reactions indicate that the contribution of the 18 F(p,γ) route to the formation of 19 Ne is small.

The astrophysical reaction rate for the {sup 18}F(p,{alpha}){sup 15}O reaction

Proton and alpha widths for a 3/2{sup +} ({ell}{sub p} = 0) state in {sup 19}Ne at E{sub x} = 7.1 MeV have been extracted using the results of recent measurements of the {sup 18}F(p,{alpha}){sup 15}O reaction. This {ell}{sub p} = 0 resonance dominates the astrophysical reaction rates at temperatures T{sub 9} > 0.5.