An Investigation of the Compound Nuclei ⁷Li and ⁷Be

Author: Spiger, Robert John

Year: 1967

Degree: Dissertation (Ph.D.)

Advisor: Tombrello, Thomas A.

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/75XC-EF29

Abstract

The differential elastic scattering cross section has been measured for the scattermg of 3He from 4He and the scattering of 4He from tritium. Incident particle energies of 5 to 18 MeV and 4 to 18 MeV, respectively, were used. Gas targets were used and solid state silicon detectors were employed to detect the scattered particles. Data were also obtained for the reactions 4He3He,p)6Li, 4He3He,p1)6Li*, 3H(α,n)6Li and 3H(α,n1)6Li*. Levels are seen at 4.65, 6.64, 7.47 and 9.7 MeV in 7Li and at 4.57, 6.73, 7.21 and 9.3 MeV in 7Be. A phase shift analysis suggests assignments of 7-/2 and 5-/2 for the two lower levels in 7Li, confirms the 5-/2 assignment of the 7.47 level and suggests a 7-/2 assignment for the new level at 9.7 MeV. Similarly in 7Be, the assignment of 7-/2 and 5-/2 for the lower two levels is reconfirmed and an assignment of 7-/2 is suggested for the new level at 9.3 MeV. The reduced widths for α and nucleon emission were determined by fitting the phase shifts near each level with a single and/or double level formula from the R-matrix formalism of Lane and Thomas (1958). The results of the analysis are discussed and compared with predictions of some recent nuclear model calculations.

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