R P Singhal

A shell-model investigation of the binding energies of some exotic isotopes of sodium and magnesium

Standard shell-model calculations of the binding energies of the neutron-rich isotopes of sodium and magnesium are in strong disagreement with the experimental values near N=20. The authors show that the discrepancy can be explained by allowing neutron excitations from the d3/2 shell into the f7/2 shell.

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.

Electromagnetic properties of the 01+, 21+, 41+ states in 20Ne, 24Mg, 28Si, 32S☆

Abstract The 0 + , 2 + , 4 + sequence in the 4 N nuclei in the 1s-0d shell has been examined by comparing the results of a large-basis shell-model calculation with electron scattering data. While the ground state is well described by the shell-model wave function there is evidence that extra s-d space configurations play an important role in defining the radial shapes of inelastic transition densities. For 0 + → 4 + transitions, mixing of the Og shell is important. The Chung-Wildenthal interaction shows erroneous behaviour in the description of some of the electromagnetic properties of these states.

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.

Elastic scattering of electrons from 20,22Ne

Elastic electron scattering cross sections have been measured for 20,22Ne in the momentum transfer range 0.21-1.30 fm-1. For a two-parameter Fermi distribution the root-mean-square radius of 22Ne is found to be 0.982+or-0.003 times that of 20Ne. The half-density radius is increased by 3.6+or-0.4% in going from 20Ne to 22Ne but the surface thickness is reduced by 7.4+or-1.1%. Comparison is made with large-basis shell-model calculations which describe the relative cross sections quite well.

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.

Inelastic electron scattering from 29Si

The excited states of 29Si up to 8.3 MeV excitation energy have been studied by inelastic electron scattering in the momentum transfer range 0.4 to 1.05 fm-1. Ground-state transition probabilities and transition radii were obtained for the levels excited. At lower excitation energies the transition probabilities agree with previous work. A number of high excitation and high-multipolarity levels are studied for the first time, and several previously tentative spin-parity assignments are confirmed. Transition probabilities for L=2, 3 and 4 are compared with the predictions of the intermediate coupling model and the Nilsson and shell models.

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.