J.L.C. Ford

COULOMB EXCITATION OF VIBRATIONAL TRIPLET STATES AND OCTUPOLE STATES IN THE EVEN CADMIUM NUCLEI

Abstract Oxygen-16 ions with energies of 42 to 49 MeV have been used to Coulomb excite higher states in the even cadmium isotopes. Double E2 excitation of the 0 + state at 1133 keV in 144 Cd has been observed. The E2 transition between the excited 0′ + state and the first 2 + state is strongly enhanced, i.e., B( E 2, 0′ → 2) B( E 2, 2 → 0) = 0.85±0.17 . The second 2 + state and the 4 + state in 116 Cd are degenerate to within 5 keV at 1222 keV excitation. The values obtained for the ratio B( E 2, 4 → 2) B( E 2, 2 → 0) are 1.42±0.19, 1.82±0.23, 1.80±0.23 and 1.63±0.36, respectively for 110 Cd, 112 Cd, 114 Cd and 116 Cd. States at 2051±16, 1968±16, 1945±16 and 1900±16 keV are excited in 110 Cd, 112 Cd, 114 Cd and 116 Cd, respectively. If these states are interpreted to be the result of direct E3 Coulomb excitation, the B (E3, 0 → 3) are 10.3, 10.6, 9.0, and 7.5×10 4 e 2 fm 6 with an accuracy of ±20% provided the branching ratio of cascades to crossover from the 3 − state is large compared to unity. These B (E3) values represent enhancement of 13 to 20. They are 3 to 6 times smaller than the results derived from yield measurements with 14–15 MeV α particles at Copenhagen.

A microscopic description of inelastic 12C scattering from 208Pb

Abstract Heavy-ion inelastic scattering is described microscopically by using an effective nucleon-nucleon interaction and RPA hole-particle wave functions. The relative cross sections for different multipoles can be sensitive to the range of the interaction. The strength is determined by fitting elastic scattering. The model is used to analyze 98 MeV 12C ions exciting 208Pb. The range required is shorter than that for the bare interaction between nucleons. Collective model fits are also presented for comparison.

Population of high spin states in 22Na by means of the 10B(16O, α) reaction☆

Abstract Strong selectivity has been observed in the population of states in 22 Na up to high excitation energies. Angular distributions were measured, and a comparison with Hauser-Feshbach calculations allow us to select strong candidates for the high-spin members of the K π = 3 + , T = 0 and K π = 0 + , T = 0 bands in 22 Na.

The 18O(α, p) reaction and the beta decay of 21F

Abstract The 18O(α, p)21F reaction has been studied in the bombarding energy range 7.78 to 9.95 MeV by observing, with approximately 2π geometry, the beta particles following the 21F decay. Prominent peaks in the yield curve occur at incident particle laboratory energies of about 7.86, 8.36, 8.61, 8.71, 8.83, 8.94, 9.16, 9.28, 9.43 and 9.82 MeV. The observed width of the peaks exceeds the experimental resolution of about 20 KeV. A half-life of 4.35±0.04 sec was determined for the 21F beta decay.

Search for resonances in 12C(9Be, α)17O

Abstract Excitation functions at 7° (lab) have been measured from E c.m. = 5.1 to 11.4 MeV in approximately 114 keV steps for 15 groups of final states in 17 O populated by the 12 C( 9 Be, α) reaction. Statistical tests have been used to locate possible non-statistical structure in the excitation functions. Possible anomalies were found near E c.m. = 6.3, 7.5, 8.9 and 9.7 MeV. Angular distributions were measured at E c.m. = 9.20, 9.71 and 10.23 MeV for the three lowest excited states in 17 O. The data have been compared with Hauser-Feshbach calculations in addition to the following reaction mechanisms: compound plus a single resonance, compound plus interfering resonances and compound plus direct reactions.

A search for interference effects between nuclear resonance and Coulomb excitation in the Na23(p, p′) reaction

Abstract The narrow, isolated resonance in the Na23(p, p′) reaction at 873 keV, situated upon a continuum due to Coulomb excitation, would appear to be a favourable case for observing interference effects between compound nucleus inelastic scattering and Coulomb excitation. The yield of 439 keV gamma radiation emitted from the first-excited state of Na23 was measured from 828 to 1100 keV incident proton bombarding energy. To within the accuracy of the experimental data, about ±8%, the non-interfering compound nucleus and Coulomb excitation contributions adequately account for the resonance shape, although the presence of an interference effect cannot be definitely excluded.