Elastic Scattering of Nitrogen by Nitrogen

The differential cross section for the elastic scattering of nitrogen from nitrogen was measured for incident nitrogen laboratory energies of 15.0, 17.7, 19.2, and 21.7 Mev and laboratory angles from 15° to 55°. The scattering occurred in nitrogen gas and the particles were detected with a nuclear emulsion placed in a one-slit camera. At 15 Mev, the scattering is entirely due to the Coulomb potential. The interference term in the Mott scattering cross section of two identical particles can be seen as a rise in the cross section near 45°, illustrating the fact that nitrogen is a Bose-Einstein particle. The angular resolution is not sufficient to enable the precise measurement of the spin. At the higher energies the cross section drops below the Mott cross section at angles greater than 30°, due to the nuclear absorption of the particles as the apsidal distance approaches the sum of the two nuclear radii. At an energy of 21.7 Mev and an angle of 45°, the cross section is $\frac{1}{5}$ of the Mott cross section. A calculation which uses the strong absorption model of Blair, fits the differential cross section at 21.7 Mev quite well. In order to fit the data, the contributions from values of $l$ up to 6 must be subtracted from the Coulomb cross section; this indicates that the nuclear radius of nitrogen is 4.0×${10}^{-13\mathrm{}}$ ${\mathrm{cm}}^2$. From this calculation the total nuclear absorption cross section for 21.7-Mev nitrogen on nitrogen is inferred to be 3.4×${10}^{-25\mathrm{}}$ ${\mathrm{cm}}^2$.