The Inelastic scattering of electrons from carbon - 12
Beer, George Atherley
In this thesis we present measured values of the nuclear matrix element for the 19.4 MeV level in 12C and describe the experimental equipment which was used for this investigation of nuclear structure by the technique of electron scattering. Previous electron scattering measurements on this level have been made at momentum transfers less than 120 MeV/c and greater than 270 MeV/c. We have measured the matrix element for this level in the previously uninvestigated region of momentum transfers between 120 MeV/c and 220 MeV/c. All present measurements were made at the largest attainable scattering angle to enhance the transverse terms in the cross section. The experimental matrix elements have been compared with theoretical results both fora 1- and for a 2- level predicted to lie in this energy region. These theoretical particle-hole calculations show that in the region of intermediate momentum transfers which we have investigated, the magnitude of the matrix element is most sensative to the spin-parity assignment. The 1- matrix element has a minimum in this region whereas the 2- matrix element has a maximum. The measured matrix elements are in satisfactory agreement with the particle-hole calculations for a 2- level in 12c and the present values favourably compare with other measurements in the region of overlap.