Accession Number : AD0669924

Title :   16O(ALPHA, 2 ALPHA)12C G.S. REACTION MECHANISMS NEAR 25 MEV,

Corporate Author : ILLINOIS UNIV URBANA DEPT OF PHYSICS

Personal Author(s) : Parker,A. W. ; Allen,J. A. ; Yerke,R. L. ; Stotland,V. G.

Report Date : MAY 1968

Pagination or Media Count : 58

Abstract : Measurements of the angular correlation between the two alpha particles emitted in the reaction 16O(alpha, 2 alpha)12C g.s. at incident energies near 25 MeV suggest that this reaction can be described in terms of both sequential and one-step knockout processes. The sequential reaction proceeds as inelastic alpha-particle scattering followed by alpha-particle decay of the excited levels of 16O to levels of 12C. Only the transitions to the ground state of 12C were studied. The most strongly excited levels were those at 11.1 MeV and 13.88 MeV. The strong energy dependence of the cross section for the reaction going through the 13.88 MeV level indicates the existence of a broad state in 20Ne with an excitation energy near 24 MeV. Apparently, resonance effects are present in the initial-state interaction at this excitation. Any quasi-elastic scattering appears as a background under the peaks of the sequential reaction. The angular distribution of this background is in limited agreement with the predictions of a modified Born approximation model which takes into account the final state interaction between the two alpha particles. (Author)

Descriptors :   (*OXYGEN, *ALPHA BOMBARDMENT), ALPHA PARTICLE REACTIONS, CARBON, PARTICLE TRAJECTORIES, INELASTIC SCATTERING, ISOMERIC TRANSITIONS, NUCLEAR ENERGY LEVELS, NUCLEAR RADIATION SPECTROSCOPY, ALPHA CROSS SECTIONS, NEON, EXCITATION, BACKGROUND

Subject Categories : Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE