First Direct Measurement of the 17F(p,gamma)18Ne Cross Section.

The rate of the {sup 17}F(p,{gamma}){sup 18}Ne reaction is of significant importance in astrophysical events like novae and x-ray bursts. The decay of {sup 17}F is thought to help drive the expansion of the nova envelope, and the {sup 17}F(p,{gamma}){sup 18}Ne reaction affects the production of {sup 18}F, a target of gamma-ray astronomy, as well as being an important link in the ({alpha},p) reaction chain during the ignition phase of x-ray bursts. A 3{sup +} state in {sup 18}Ne predicted to dominate the rate was found at 599.8 keV using the {sup 17}F(p,p){sup 17}F reaction [1], but the resonance strength was unknown. For the first time, the {sup 17}F(p,{gamma}){sup 18}Ne reaction has been measured directly with the Daresbury Recoil Separator, using a mixed beam of radioactive {sup 17}F and stable {sup 17}O from the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. A {gamma} width was found for the 599.8 keV resonance in {sup 18}Ne, and an upper limit on the direct capture S factor was determined at an intermediate energy of 800 keV.