Measurement and interpretation of electromagnetic transitions in 51V

Abstract

Angular correlation measurements in the 180° geometry for the 48Ti(α, pγ) 51V reaction were used to determine the γ-ray decay properties of states in 51V at 0.32, 0.93, 1.61, 1.81, 2.41, 2.55, 2.68 and 2.70 MeV. Coulomb excitation measurements with 32S ions, using a thick 51V target and a Ge(Li) detector, were used to deduce the B(M1) and B( E2) reduced transition probabilities for the decays of the 0.32, 0.93, 1.61 and 1.81 MeV states. For these states the M1 transitions are found to be retarded by factors ranging from about 400 to over 10000, while the E2 transitions are enhanced by about an order of magnitude relative to the Weisskopf estimate. Shell-model calculations were performed for 51V considering all basic three proton states in the f-p shell and assuming a 48Ca core. Kuo and Brown two-body matrix elements were used. Remarkably good agreement is obtained between the calculated and measured transition rates, supporting the shell-model predictions of a high-configuration purity for the six levels of the basic f 7 2 3 multiplet. By contrast, the B(M1) values predicted by the strong Coriolis coupling model of Scholz and Malik strongly disagree with the measured values, generally being two or three orders of magnitude too large. We conclude that the spherical shell model provides an excellent description of the low-lying states in 51V and, contrary to Scholz and Malik, we find no evidence for deformation in this nucleus.