The Frequency of Occurrence of the Disintegrative-synthesis of Oxygen 17 from Nitrogen 14 and Helium

By the use of a modified Wilson-Shimizu apparatus 39000 photographs were taken of the tracks of $\alpha$-rays in nitrogen. The rays used were those from thorium $C$ and $C^{\prime }$ as in earlier work in this laboratory. Two disintegrative syntheses were obtained of oxygen of mass 17 and isotopic number 1 by the attachment of the $\alpha$-particle in each case to the nucleus of an atom of nitrogen. Evidence is presented which shows that the nitrogen atoms which are acted on in this way are in general those of mass 14 and isotopic number 0. The number of disintegrative syntheses per million $\alpha$-tracks is 8, while the average of this and all other work gives 15. In this work the ratio of the number of inelastic to elastic collisions was smaller than in any earlier work, but this was due largely to the occurrence of an abnormally high number of elastic collisions.