The determination of the strength of the electric quadrupole transition between the ground state and first excited state with spin-party 2+ (the B(E2) value) in an even-even nucleus provides a measurement of the low-lying quadrupole collectivity. The B(E2) values for the Z=14 nuclei 34,36,38,40,42Si were measured via intermediate-energy Coulomb excitation at the National Superconducting Cyclotron Laboratory in East Lansing, Michigan. The secondary beams were produced by the fragmentation of a 48Ca primary beam guided onto a high-Z secondary target. De-excitation gamma-rays, indicative of the inelastic process, were detected around the secondary target position with the high-efficiency scintillator array CAESAR in coincidence with scattered particles tracked on an event-by-event basis in the S800 spectrograph. The results comprise the first measurements of the quadrupole collectivity of 40,42Si. The measured B(E2) values are compared to large-scale shell model calculations and provide insight into the evolution of shell structure and deformation in this region.
Read
