R.J. Ascuitto

The importance of indirect transitions on (p, t) reactions on deformed nuclei

Abstract The (p, t) reaction on deformed nuclei has been computed with the inclusion of indirect transitions that go through intermediate rotational states. The indirect transitions are almost as large as the direct for the 2 + state and their inclusion is essential to bring about agreement with the shape and magnitude of the differential cross section. For the 4 + state some of the indirect transitions are even stronger than the direct one. The sensitivity of the reaction to β 4 and β 6 terms in the shape has been investigated and found to be weak.

Accessory Mitral Valve Tissue Causing Left Ventricular Outflow Obstruction (Two-Dimensional Echocardiographic Diagnosis and Surgical Approach)

Accessory mitral valve tissue, a rare cause of left ventricular outflow tract obstruction, can be difficult to diagnose preoperatively and confusing even at surgery. The reported case illustrates how preoperative evaluation can be made using two-dimensional echocardiography combined with Doppler flow analysis. The intraoperative technique for removing the accessory tissue without causing damage to the native mitral valve is discussed.

Spectroscopy with two-nucleon transfer reactions in deformed nuclei: (II). Rare-earth K = 0 bands studied with the (p, t) reaction

Abstract The ratio of the (p, t) strength to excited K = 0 bands relative to the ground band varies from a few to about 40 % across the rare-earth region. This behaviour is reproduced by a calculation that uses conventional pairing plus quadrupole interactions for the structure calculation and includes inelastic excitations in the treatment of the reaction.

One-nucleon transfer reactions in deformed nuclei☆

Abstract The one-nucleon transfer reaction on deformed nuclei has been computed with the inclusion of indirect inelastic transitions that go through intermediate rotational states. The specific examples considered are171Yb(d, p), 172Yb(p, d) and 186W(p, d). Anomalies in the shapes of of experimental angular distributions with respect to predictions of the distorted-wave Born approximation are shown to be reproduced when these higher-order inelastic processes are taken into account. Consideration is also given to the deuteron optical potential needed for these studies.

Spectroscopy with two-nucleon transfer reactions in deformed nuclei: (I). Form factors

Abstract A method for the evaluation of two-nucleon transfer form-factors is devised, which is suitable for the treatment of reactions between deformed nuclei. The nuclear-structure-dependent parts are evaluated in a rotating (intrinsic) frame.

Inelastic scattering calculations with projected Hartree-Fock wave functions. II - Coupled-channel treatment.

Abstract A microscopic coupled-channel study of inelastic proton scattering from, 20 Ne and 24 Mg is presented. At least the 0 + , 2 + , and 4 + members of the ground state rotational band of each nucleus are included explicitly in the coupled equations, using nuclear wave functions obtained by projecting states of good angular momentum from deformed Hartree-Fock intrinsic states. The scattering results are compared with the distorted-wave Born approximation (DWBA) and experiment; truncation of the nuclear model space is also investigated. The results obtained with this microscopic model confirm conclusions drawn earlier based on the macroscopic model; in particular, the shapes and deformations predicted by the macroscopic model are well reproduced by the projected Hartree-Fock model, which is based purely on energy considerations. However, it is found that the magnitudes of cross sections to the higher levels are considerably smaller than experiment. A collective-model calculation, using optical potentials inferred from the intrinsic HF distributions, yields much better results. This suggests that microscopic descriptions of inelastic scattering are quite sensitive to details of the nucleon-nucleon interaction, which does not explicitly enter into the macroscopic description.

Quadrupole transfer strength for deformed rare-earth nuclei as studied with heavy-ion induced two-nucleon transfer reactions☆

Abstract The quadrupole transfer strength associated with the deformed pairing field has been studied by measuring ground-state rotational band angular distributions for the ( 12 C, 14 C) reaction on 154 Sm, 182 W and 186 W. It is shown that, through competition between direct and multistep transitions involving intermediate inelastic excitation, reactions of this type may provide a useful means of studying an underlying structure description of deformed nuclei.

Inelastic nuclear-coulomb interference and direct-two-step interference in heavy-ion induced two-nucleon transfer reactions on rare-earth nuclei☆

Abstract The almost pure two-step population of the 2 + ground-state rotational band member of 184 W in the two-neutron transfer reaction 186 W( 12 C, 14 C) 184 W, resulting in an angular distribution characterized by a dramatic nuclear-Coulomb interference minimum in the vicinity of the grazing angle, is compared with the corresponding angular distribution for the two-proton transfer reaction 186 W( 12 C, 10 Be) 188 Os, where the interference minimum is shown to arise primarily from direct-two-step (nuclear-dominated) interference.

APPROXIMATE TREATMENT OF CORRELATIONS IN NUCLEAR SPECTROSCOPY. II. TWO- NUCLEON TRANSFER IN THE LEAD REGION.

Abstract The effect of ground state correlations on calculated two-nucleon transfer cross sections for the reactions (p, t), (t, p), ( 3 He, p) an ( 3 He, n) in the lead region is investigated. The sensitivity to ground state correlations is isolated by comparing calculated DWBA cross sections obtained by using two-nucleon shell-model (2n SM) states with those obtained by using two-nucleon random-phase approximation (2n RPA) state descriptions. The correlations obtained in a 2n RPA calculation produce strong enhancements of the calculated ground state to ground state transitions involving the transfer of two identical particles over the same transitions calculated without correlations. In addition, certain other transitions are substantially affected while others are unaltered. The sensitivity of the calculated cross sections to the model and the choice of effective interaction is investigated and compared with the sensitivity of other calculated quantities.

Persistent Left Superior Vena Cava Causing Subdivided Left Atrium: Diagnosis, Embryological Implications, and Surgical Management

A 3-month-old infant is described in whom a persistent left superior vena cava impinged on the posterior wall of the left atrium, producing a subdivided left atrium with left-to-right shunting and congestive heart failure. To our knowledge, this anomaly has not previously been reported. The preoperative diagnosis, surgical management, and embryological implications are discussed.