Thick targets of ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ were bombarded with bombarded with ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ ions accelerated in the Oak Ridge tandem Van de Graaff, and cross sections were measured for the nucleon-transfer reactions ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$,${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$)${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$,${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$)${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ from 10.5 to 26.5 MeV. The amount of ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ present in each irradiated sample was determined by the detection of the 110- and 20.5-min positron activities, respectively, characteristic of the two nuclides. It was found that the cross section for the neutron-transfer reaction was ∼2.5 times greater than that of the proton-transfer reaction. This is in contrast to results obtained previously for similar transfer reactions induced by ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ ions on ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ targets. Reaction cross sections for the incident ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ to transfer a nucleon to the target nuclei ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ have been measured, and are approximately independent of whether a neutron or a proton is transferred. Previously published data for the reactions ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$,${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$)${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$,${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$)${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$, and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$,${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$)${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, were examined together with the data for the ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$(${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$,${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$)${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ reaction. By applying the tunneling theory of Breit et al. to these results, two values (one for each target nucleus) were extracted for the ratio of the reduced width of the transferred neutron in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ to that in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$. Both ratios were found to be ∼3.7. The internal consistency lends encouragement to this method of reduced-width extraction. Graphite disks were bombarded with ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ ions, and the yield of ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ from ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ on carbon in the energy range investigated was found to be neglegible when compared with that measured for ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ targets. Excitation functions were also measured for the compound-nucleus reactions ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}({}_{}{}^{19}{}_{}{}^{}\mathrm{F}, \alpha p){}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{19}{}_{}{}^{}\mathrm{F}, 2p){}_{}{}^{29}{}_{}{}^{}\mathrm{Al}$, and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}({}_{}{}^{19}{}_{}{}^{}\mathrm{F}, 2\alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$.

• Received 9 November 1967

DOI:https://doi.org/10.1103/PhysRev.167.957