W.J. Vermeer

A measurement of B(E3;0+ → 31−) and some E2 transition probabilities in 132, 134, 136, 138Ba using Coulomb excitation

Abstract Reduced transition probabilities, B (E2) and B (E3), have been measured for low-lying 2 + and 3 − states in 132, 134, 136, 138 Ba using Coulomb excitation by 40 MeV 12 C ions. The B (E2) values are in general consistent with previous measurements and the B (E3;0 + → 3 1 − ) values are 0.176 ± 0.022, 0.148 ± 0.018, 0.155 ± 0.018 and 0.133 ± 0.013 e 2 · b 3 for 132, 134, 136, 138 Ba respectively. These B (E3) values correspond to about 24 to 17 W.u. and such enhancements suggest that these 3 − states have an essentially collective character which may be attributed to octupole vibrations.

An improved determination of the quadrupole moment of the first excited state of 208Pb

Abstract Coulomb-excitation studies of the 3 − first excited state of 208 Pb using 12 C and 16 O projectiles for a range of angles give −0.34 ± 0.15 e b for the static quadrupole moment ( Q 3 − ) and 0.611 ± 0.012 e 2 b 3 for B (E3; 0 + → 3 − ) . The value obtained for Q 3 − is substantially more precise and reliable than previous determinations, and is larger in magnitude than theoretical predictions.

An experimental verification of the validity of the reorientation-effect technique for the determination of nuclear quadrupole moments

Abstract The static electric quadrupole moment of the ground state of 7 Li has been determined using the reorientation effect in Coulomb excitation. The result obtained (−4.0 ± 1.1 e fm 2 ) is in excellent agreement with values reported from standard techniques and thus provides a strong verification of the validity of the reorientation-effect technique for the determination of nuclear quadrupole moments.

Electric quadrupole moment of the first excited state of 12C

Abstract The static electric quadrupole moment Q 2+ of the first excited state of 12 C has been measured using Coulomb excitation of 12 C projectiles by a 208 Pb target. The result is Q 2+ =+6 ±3 e fm 2 , which indicates a substantial oblate deformation, consistent with most theoretical expectations.

A measurement of the giant-dipole-resonance contribution to the Coulomb excitation of 17O

Abstract The contribution of the giant dipole resonance to the Coulomb excitation of 17 O by 208 Pb has been measured to be 5.7 ± 0.4 times the value given by the hydrodynamic model. This result has significant implications for the determination of B (E2) values and quadrupole moments from Coulomb excitation measurements.

The value of B(E2; 32− → 12−) FOR 7Li

Abstract Previous experimental information from the Coulomb excitation of the 1 2 − first excited state of 7Li is discussed and reanalysed, giving B(E2; 3 2 − → 1 2 − ) = 7.59 ± 0.10 e 2 · fm 4 .

Energy dependence of the 16O208Pb effective interaction

Abstract The Coulomb-nuclear interference in the excitation probability of the 2.615 MeV (3−) state of 208Pb by 16O at θCM=172° for bombarding energies 57 MeV ⩽Elab⩽79 MeV has been studied. The data are described by an effective interaction which has a behaviour similar to that expected from the dispersion relation connecting the real and imaginary parts of the generalized optical potential.

Electric quadrupole moments of the first excited state of 192Os

Abstract Coulomb excitation by 4 He and 12 C projectiles has been used to determine electric quadrupole moments of the first excited state of 192 Os. It is found that B (E2; 0 + 1 → 2 + 1 ) = 2.030 (13) e 2 b 2 , in excellent agreement with previous work. The static moment Q (2 + 1 ) is found to have the value −0.86 (20) e · b , in good agreement with the result of a muonic X-ray experiment.

A simple method of accurate reaction angle determination using a magnetic spectrograph

Abstract A simple and accurate method of reaction angle determination in experiments using a magnetic spectrograph is described. The method is based on elastic scattering kinematics and uses the same beam and target conditions as those for which the angle determination is required. A precision of ±0.05° is attainable.

Low-energy behaviour of the heavy-ion optical model potentials for 12C and 16O scattering from 208Pb

Abstract The probability of exciting the first 3 − state of 208 Pb has been studied using the optical-model potential. In the neighbourhood of the Coulomb barrier the strength of the imaginary part of the potential has been assumed to vary linearly with bombarding energy. The strength of the real part of the potential has been calculated using the dispersion relation. An excellent fit to experimental excitation functions has been obtained for both 12 C + 208 Pb and 16 O + 208 Pb reactions. The calculated angular-momentum distributions for various bombarding energies also agree very well with the experimental data.