Nick Jelley

Abstract:

Angular distributions have been measured for the (9Be, 10B[3+, 0.0]) and (9Be, 10B[1+, 0.72]) reactions on 63Cu, 54Fe, 26, 24Mg and 16O at 43 MeV and on 40Ca at 45 and 30 MeV. EFR-DWBA calculations which used optical potentials obtained from the measured elastic scattering of 9Be from 26Mg, 16O and 40Ca and 10B from 25Mg and 39K have generally reproduced well the shape of the cross sections. Initially, a standard prescription was used in the form-factor calculation and Cohen and Kurath spectroscopic factors were assumed for 9Be-10B. Inconsistencies, concerning whether 10B was left in its ground or first excited state, of up to 60% were found between the extracted target spectroscopic factors. This anomaly was insensitive to changes in either optical-potential or bound-state parameters. A simple calculation of a two-step process could not account for the anomaly. Use of modified spectroscopic factors for the 9Be-10B system essentially removed the discrepancies except for the magnesium targets, and an improved form-factor description further alleviated the anomaly. This form-factor method uses a shell-model potential in conjunction with a surface-peaked potential, the depth of which is adjusted to give the correct asymptotic form to the wave function. © 1985.

Abstract:

The g-factor of the 3- (298 keV) state in 16N has been measured by observing the hyperfine modulation of the γ-ray anisotropy in one-electron ions recoiling in vacuum following the 2H(15N, p)16N reaction. From the observed spatial frequency the g-factor was deduced to be |g| = 0.532±0.020. Simultaneous lifetime determinations for this state and the 1- (397 keV) state in 16N gave values of τm = 131.7±1.9 ps and τm = 5.63±0.05 ps, respectively. These and other electromagnetic observables associated with the lowest four levels in 16N are compared to shell-model calculations. © 1984.

Abstract:

Elastic scattering data are presented for 6Li at 36 MeV from 12O and 26Mg and for 7Li at 28.8 MeV from 15N and at 27 MeV from 25Mg over the range 15-95 degrees in the centre-of-mass frame. Microscopic optical potentials are generated for these scattering systems using the double-folding model. The sensitivity of the potentials to the prescriptions used for the nuclear density calculations is studied. The elastic scattering data are analysed within the framework of the optical model using both Woods-Saxon potentials and double-folding model real potentials with Woods-Saxon imaginary wells. Equally good fits to the data are obtained with the phenomenological and microscopic potentials. The double-folding potentials must be normalised by factors of 0.5 or 0.6 to fit the data in all cases except for 6Li scattering from 16O, for which a normalisation of 0.8 is favoured. These results are supplemented by those from an inelastic scattering analysis using DWBA and the collective rotational model for the first 2+ states in 12C and 26Mg. The shapes of the phenomenological and microscopic potentials around the strong absorption radius are compared and the gradients are found to differ significantly for 7Li+15N and 6Li+ 12C systems.

Abstract:

We report the first observation of a laser-induced M1 transition in a fast beam. This new method has been applied to a measurement of the F=12-32 and F=32-52 hyperfine components of the 1s2p P13-P23 fine-structure interval in heliumlike fluorine. The results are 953.60(3) and 961.77(3) cm -1, respectively. From these we extract the fine-structure splitting Δ12=957.88(3) cm-1. © 1981 The American Physical Society.