Elastic Scattering ofN14byBe9

Nitrogen-beryllium elastic scattering was measured over an angular range from 32 to 144 deg in the center-of-mass system with an angular resolution of about one degree. The mean energy of the incident nitrogen ions was 27.3 Mev. To distinguish elastic scattering from other events, both the scattered and the recoil particles were detected in coincidence by thin CsI(Tl) scintillation counters. The elastic scattering differential cross section is 550 mb/sterad at 32 deg c.m. It decreases monotonically and more rapidly than ${csc}^4\left(\frac{\theta }{2}\right)$ to a shallow minimum of about 5 mb/sterad at 106 deg c.m., rises slightly, and then falls to about 2.5 mb/sterad at 144 deg c.m., the largest angle measured. The data are compared to the predictions of a sharp-cutoff model for elastic scattering, but no agreement is found between this theory and the experimental results.