E W Lees

The ground-state charge distribution of the silicon isotopes and the excited states of 28Si, 30Si

The ground-state charge distributions of 28,29,30Si have been studied by elastic electron scattering and the results compared with those from muonic isotope shift work and other electron-scattering experiments. The 21+ state at 1.78 MeV in 28Si and the 21+ state at 2.24 MeV and 22+ state at 3.50 MeV in 30Si have been investigated by inelastic electron scattering and their form factors extracted.

Elastic scattering of electrons from the N = 50 isotones: 88Sr, 89Y, 90Zr and 92Mo

Abstract Elastic electron scattering from 88 Sr, 89 Y, 90 Zr and 92 Mo has been measured in the momentum transfer range from 0.25 fm −1 to 1.15 fm −1 . The difference charge density distributions are compared with the predictions of the independent particle model. An estimate of the model-dependence of the difference density distribution is made. The data are found to be most sensitive to regions of the charge distribution from 3.5 fm to 4.5 fm.

Elastic electron scattering from the stable isotopes of magnesium

Elastic electron scattering cross sections from the isotopes 24Mg, 25Mg and 26Mg have been measured in the momentum transfer range 0.20-1.15 fm-1. The individual RMS radii and also the differences between the isotopes are investigated. The measured form factors are compared with the predictions of an extended Nilsson model calculation.

Inelastic scattering of electrons from 27Al

Abstract Electron scattering form factors have been measured for the excitation of 2.21 MeV ( 7 2 + ) 2.734 MeV ( 5 2 + ) and 3.00 MeV ( 9 2 + ) states in 27Al using values of momentum transfer between 0.31 and 1.05 fm−1. Reduced ground-state transition probabilities and transition radii are obtained for the 2.21 and 3.00 MeV states. Intermediate-coupling calculations are shown to reproduce the energy spectrum of 27A1 but not the transition matrix elements and the form factors. Much better agreement is obtained using a large basis shell-model calculation.

B(E2 spin up) and Q21+ measurements in the even-mass Cd isotopes

Form factors for the inelastic scattering of electrons from the even-mass isotopes 110-116Cd were measured. The B(E2 spin up) and Q(21+) deduced from these data confirm the results of a recent measurement of these quantities carried out by Coulomb excitation.

Excitation of vibrational states in 114Cd by inelastic electron scattering

Inelastic electron scattering form factors for excitation of states up to 2.4 MeV in 114Cd have been obtained in the momentum-transfer range between 0.37 and 1.09 fm-1. The 21+ quadrupole moment and 22+ radiative transition rates are deduced using a vibrational model in which one- and two-phonon states are mixed. The results obtained are in excellent agreement with recent reorientation effect measurements. Inclusion of higher momentum transfer data favours a 3- assignment for the 1.957 MeV level. The 4+ level at 2.35 MeV is shown to have an enhanced transition rate, making it a candidate for the single-phonon hexadecupole transition.

Vibrational states in 108Pd studied by elastic and inelastic electron scattering

The elastic electron-scattering form factor, and inelastic form factors for the 21+ (0.434 MeV), 22+ (0.931 MeV) and 3- (2.046 MeV) states in 108Pd were measured. The ground-state charge distribution parameters were obtained from a phase-shifted analysis of the elastic form factor. Analysis of the 21+ and 22+ form factors in the anharmonic vibrator model yields the reduced transition probabilities and the 21+ quadrupole moment (Qx, x=21+) which is in excellent agreement with recent Coulomb reorientation measurements. The 3- form factor is well described by the assumption that this state is a pure octupole vibration.

Inelastic electron scattering from 25Mg

The excited states of 25Mg have been studied by inelastic electron scattering in the momentum transfer range 0.3 to 1.15 fm-1. The reduced transition probabilities and transition radii were measured for seven levels below 4.1 MeV excitation energy and the transition probabilities are shown to be more precise than existing measurements. A search for the hexadecupole strength to the 11/2+ levels in the vicinity of 5-6 MeV excitation energy was also carried out. The applicability of an extended Nilsson-model description for the ground-state band of 25Mg was also investigated by comparison with the known electromagnetic strengths, and, more crucially, by comparison with the measured form factors.

Measurements of the nuclear charge distribution in the cadmium isotopes

The RMS radii (r2)1/2 of the charge distributions of the even isotopes 110<or=A<or=116 of cadmium have been measured by electron scattering, and the differences delta (r2) for 106<or=A<or=116 by optical isotope shifts. The methods indicate the same trend in delta Jr2) but there is quantitative disagreement.

An experimental and theoretical study of the low-lying states of 15N

Form factors for the inelastic scattering of electrons from 15N were measured for the excitation of the 6.32 MeV 3/2- state and of the 5.3 MeV 5/2+ 1/2+ doublet. The experimental data obtained resolve apparent discrepancies between the results deduced from the previous studies of 15N by electron scattering, and demonstrate that even large-basis shell-model calculations using the Kuo interaction do not produce realistic wavefunctions for these states.