Angular distributions of 18F from the reaction 16O( 14N, 18F) 12C

Abstract

The reaction 16O( 14N, 18F) 12C was investigated at incident energies of 20. 27 and 33 MeV by bombarding thin nickel oxide targets with 14N ions accelerated in the Oak Ridge Tandem Van de Graaff. Angular distributions were obtained by stopping the radioactive 18F particles in aluminium foil annuli which encompassed known angular increments. After bombardment these annuli were counted under shielded, calibrated Geiger-Mueller counters. The 18F differential cross sections were found to be peaked in the forward direction and to exhibit some structure at larger angles. From the experimental data it was concluded that the production of 18F by the evaporation of three alpha particles from the compound nucleus 30P was negligible. A distorted-wave Born approximation calculation was used in an attempt to fit the data. A good fit to the experimental results at 33 MeV was found when it was assumed that alpha-particle transfer from 16O occurred, with the residual 12C nucleus left in its 4.43 MeV state. Calculations at 20 and 27 MeV, however, did not yield satisfactory fits to the data.