Proton-hole states in 115In observed in the 116Sn(d, 3He) reaction

The ¹¹⁶Sn(d, ³He)¹¹⁵In reaction has been investigated at E_d = 50 MeV. Thirteen transitions to states up to 3 MeV excitation energy were studied. The measured angular distributions were compared with DWBA calculations and transferred angular momenta and spectroscopic factors were deduced. Levels at 1.04, 2.23 and 2.52 MeV were found to be excited most likely by l = 3 angular momentum transfer in contrast to previous investigations at lower incident energies in which no l = 3 transitions have been observed.     

High-resolution investigation of the 112Sn(p,d)111Sn reaction

The ¹¹²Sn(p, d)¹¹¹Sn reaction was studied at a proton energy of 27.45 MeV. The outgoing deuterons were momentum analyzed with an Enge split-pole spectrograph and recorded with position-sensitive solid-state detectors with a total resolution between 12 and 16 keV. Angular distributions were compared with DWBA calculations in order to extract l-values, spectroscopic factors, single-quasiparticle energies and occupation probabilities. In the gross structure between 3 and 6 MeV, which was interpreted as being due to the pickup of deeply bound neutrons, several discrete peaks were also found with an angular distribution characteristic for l = 1 or 4 transfer. The excitation of core-coupled states was investigated by performing two-step DWBA calculations. The results of the present experiment are compared with previous experimental results and with number-projected BCS calculations.     

The 19F(p,d)18F reaction studied at Ep = 19.3 MeV

The ¹⁹F(p, d)¹⁸F reaction was used at E_p = 19.3 MeV to study the level properties of ¹⁸F up to 6 MeV excitation energy. Angular distributions were measured over the angular range θ_lab = 10°–70° with an overall resolution of 35 keV. The experimental data were analyzed by DWBA theory to obtain l_n and C²S_l values, which were compared with existent theoretical nuclear structure calculations.     

The 93Nb(p,d)92Nb reaction at 26.3 MeV

The ⁹³Nb(p, d)⁹²Nb reaction was studied at a proton energy of 26.3 MeV. Angular distributions were obtained for outgoing deuterons to 37 states in ⁹²Nb up to an excitation energy of 4.2 MeV. The results were compared with DWBA calculations to extract l-values and spectroscopic factors. Fourteen previously unobserved l = 1 transitions were measured.     

A proton stripping study of92Nb

Levels up to energies of 4 MeV have been studied with the⁹¹Zr(³He,d)⁹²Nb reaction with an incident particle energy of 25.5 MeV. The product deuterons were analyzed by a split-pole spectrometer. Angular distributions were obtained for many of the transitions and compared with DWBA calculations. The assigned transferl values and spectroscopic factors were used to assign shell model structures to these levels.     

Proton-hole states in 57Co studied with the 58Ni(d, 3He) 57Co reaction at 78 MeV

The ⁵⁸Ni(d, ³He)⁵⁷Co reaction was measured at a bombarding energy of 78 MeV. Energy levels up to 7.0 MeV excitation energy in ⁵⁷Co were studied. Angular distributions of the ³He particles, corresponding to transitions to the ground state and to 42 excited states in ⁵⁷Co, were analyzed in the range of θ_lab = 2.7° to 25°. Exact finite-range DWBA calculations were employed to extract l-values and spectroscopic factors. Shell-model calculations were carried out in an fp-shell model space. In addition, calculations of the energy levels in ⁵⁷Co were performed in the SU(6) particle-vibration model (PTQM). Satisfactory agreement is observed between the experimental results and both theoretical predictions.     

Study of form factors for single-proton transfer reactions on152Sm,154Gd and156Gd

The (³He,d) and (α,t) single-proton transfer reactions on targets of¹⁵²Sm,¹⁵⁴Gd and¹⁵⁶Gd were studied at 35MeV incident energy. Differential cross sections of rotational states built upon various single-proton configurations are compared with results of DWBA calculations which employed various radial form factors. The agreement between calculated and measured reaction cross sections is found to improve significantly when the commonly used spherical bound-state potentials are replaced by deformed ones, including deformed Coulomb and spin-orbit wells, and projected form factors are used to calculate DWBA cross sections. Discrepancies in the differential cross sections so large that they cannot be attributed to band mixing phenomena are readily explained by form factor effects.     

Investigation of the reaction 35Cl(τ, α)34Cl at Eτ = 15 MeV

The ³⁵Cl(τ, α)³⁴C reaction has been used to study the properties of ³⁴Cl levels up to an excitation energy of 5 MeV. Angular distributions of 37 levels were measured with a split-pole magnetic spectrograph, at a bombarding energy of 15 MeV. New levels have been found at 3847, 3964, 4206, 4321 and 4715 keV, all ± 10 keV. There is a strongly excited multiplet at E_x = 5.0 MeV with components at 4939 ± 11, 4958 ± 11, 4971 ± 11, 4998 ± 12 and 5010 ± 13 keV. A DWBA analysis of the α-particle angular distributions yielded l_n values and spectroscopic factors. New spin and parity assignments were obtained. The T = 1 character of the levels at E_x = 4.21 and 4.72 MeV has been determined. Experimental spectroscopic factors are compared with results from recent many-particle shell-model calculations.     

Single-neutron transfer reactions 76, 78, 80, 82Se(p,d)75, 77, 79, 81Se at EP = 33MeV

Single-neutron transfer reactions on even-even Se nuclei have been studied using 33 MeV incident proton energy from the ANU cyclograaff facility. A total of 120 levels have been seen below 4 MeV excitation energy in ^{75, 77, 79, 81}Se isotopes. Angular distributions for 88 states were extracted and analysed with DWBA theory yielding a number of new l_n assignments. Coriolis coupling calculations have been carried out for low-level spin states in all four isotopes.     

High resolution investigation of 91Mo and 92Mo via (p,d) and (p,t) reactions on 90Mo

The (p, d) and (p, t) reactions on ⁹²Mo have been studied at a proton energy of 28.0 MeV. Using an Enge split-pole spectrograph, resolutions of 11–15 keV for the detected deuterons and tritons were obtained. A total of 87 levels up to 4.9 MeV in ⁹¹Mo and 25 levels up to 4.0 MeV in ⁹⁰Mo were found, several of which were previously unknown. By comparing the measured angular distributions with DWBA calculations l-values and spectroscopic factors were determined. The results are compared with data from previous experiments on ⁹¹Mo and ⁹⁰Mo, with experiments on other N = 49 and 48 nuclei, and with theoretical calculations.     

High-resolution study of 49Cr through the (p,d) reaction

The ⁵⁰Cr(p, d)⁴⁹Cr reaction was studied at a bombarding energy of 55 MeV. Angular distributions were obtained for levels up to E_x = 10.5 MeV. The l-assignment was performed for each level and the spectroscopic factor was deduced by consulting the DWBA calculation. The strength distribution was obtained for l = 0, 1, 2 and 3. Many strongly excited states in the higher excitation region were identified as isobaric analog states (IAS) of ⁴⁹V. Fragmentation of the strength was clearly observed for these states. An accurate Coulomb displacement energy was obtained for each IAS by including the fragmented parts of the strength.     

Location of multiparticle-multihole strength in 16N via the 3-particle transfer reaction 13C(α, p)16N at 118 MeV

Differential cross sections were measured for the ¹³C(α, p)¹⁶N reaction at E_α = 118 MeV for an excitation energy range up to 14.5 MeV. Zero-range distorted wave Born approximation (DWBA) calculations were performed using microscopic form factors. Spin-parity assignments are suggested for states at 11.21 MeV (6⁻) and 11.81 MeV (7⁻) on the basis of Bansal-French-Zamick weak coupling calculations and DWBA calculations. Arguments from ¹⁶O(e, e'), ¹⁶O(p, p') and the present experiment are given relating to the location of J^π = 4⁻, T = 1 strength in ¹⁶N.     

Studies of single-neutron holes in the transitional nuclei N = 83–89: The 142Ce(d,t)141Ce and 142Ce(3He, α)141Ce pick-up reactions

The level structure of ¹⁴¹Ce up to 3.7 MeV excitation energy has been investigated by the (d, t) and (³He, α) reactions using 17 MeV deuteron and 24 MeV ³He beams respectively. The angular distributions have been analyzed with standard DWBA calculations and spectroscopic factors are deduced. The experimental information is compared to unified model calculations involving both one-particle and two-particle one-hole configurations with quadrupole and octupole vibrations of the underlying N = 82 and N = 84 core.     

Étude des niveaux du noyau 27Al par la réaction 26Mg(d,n)27Al

The ²⁶Mg(d, n)²⁷Al reaction has been studied at 6 and 8 MeV deuteron bombarding energies using the time-of-flight technique for neutron detection. The good neutron energy resolution of the present work permitted the determination of the excitation energy of 70 states populated by the reaction. Angular distributions of neutrons leading to 50 levels in ²⁷Al were measured between 0° and 100°. The experimental cross sections were analysed in the framework of the DWBA and Hauser-Feshbach theories to deduce l_p values and transition strengths. New spin and parity assignments were obtained for 11 levels. The agreement between the DWBA predictions and some of the measured angular distributions was improved by modifying the optical-model radii in both incoming and outgoing channels. The experimental results are compared with the corresponding data from previous studies and with Nilsson-model and recent shell-model calculations.     

A study of the121,123Sb(p,d) reactions

Levels of^120,122Sb have been observed using the^121,123Sb(p, d) reactions atE _p = 26.2 MeV. Thirty-two levels of¹²⁰Sb and thirty-four levels of¹²²Sb are observed below 2.0 MeV excitation with an energy resolution better than 25 keV FWHM. Experimental angular distributions were compared to DWBA calculations in order to extractl-transfers and spectroscopic factors. Strong mixing between the 3s _1/2, 2d _3/2, 2d _5/2, and 1g _7/2 neutron orbitals is observed in both nuclei. Nuclear Reactions:^121,123Sb(p, d),E=26.2 MeV; measuredσ(E _d ,θ).^120,122Sb deduced levels,l,J,π, spectroscopic factors. Enriched targets, magnetic spectrometer.     

Prior-form DWBA analysis of (3He,pd) elastic breakup at 90 MeV

Proton-deuteron coincident cross sections in ¹²C,⁵¹V,⁹⁰Zr(³He,pd) elastic breakup at 90 MeV have been calculated within the framework of the prior-form distorted-wave Born approximation (DWBA). Sufficient convergence of the calculations was obtained by including the pd relative angular momenta up to l = 4. The calculations reproduced the general trend of the coincident energy spectra and the angular correlation data, though deficiencies of the calculations were seen at some angles. The peripheral feature of the (³He, pd) elastic breakup is discussed from the angular momentum dependence of the transition amplitude.     

The (α, α), (α, α′) and (α, 3He) reactions on 12C at 139 MeV

The nucleus ¹²C was bombarded with 139 MeV α-particles to study the characteristics of the elastic, inelastic, and (α, ³He) reactions. An optical model analysis of the elastic data yielded a unique family of Woods-Saxon potential parameters with central real well depth V ≈ 108 MeV, and volume integral $\text{J}\text{4A}\text{≈ 353}\text{MeV}\text{·}\text{fm}{}^3$. By comparing the present results with those of other studies above 100 MeV, we find that the real part of the α-nucleus interaction decreases with increasing energy; the fractional decrease with energy is roughly one-half that observed for proton potentials. Using the optical potential parameters derived from the elastic scattering, first-order DWBA calculations with complex first-derivative form factors reproduced the inelastic scattering data to the 4.44 MeV (2⁺) and 9.64 MeV (3^?) states of ¹²C. For the 0⁺ state at 7.65 MeV it was necessary to employ a real, second-derivative form factor to fit the data. The deformation lengths β_lR_m and deformations β_l obtained in this and other experiments are summarized and compared. DWBA calculations using microscopic model form factors were also performed for the 2⁺ and 3^? states using the wave functions of Gillet and Vinh Mau. These reproduced the shapes and relative magnitudes of the differential cross sections. We also fit the shape of the 0⁺ differential cross section using a microscopic form factor which contains a node, which is similar to that occurring in the collective model second-derivative form factor. In the ($\text{α,}{}^3\text{He}$) reaction the differential cross sections to the ground state ($\text{1}\text{2}{}^{\mathrm{?}}$) and the 3.85 MeV ($\text{5}\text{2}{}^{\mathrm{+}}$) state in ¹³C could not be reproduced by zero-range local DWBA stripping calculations; it was necessary to employ finite-range and non-local corrections in the local-energy approximation. This DWBA analysis is notable in that unambiguous optical potentials were available for both entrance and exit channels. The ground state spectroscopic factor is in agreement with the prediction of Cohen and Kurath, while the relative spectroscopic factors agree fairly well with the rather few existing measurements of this kind.     

Structure of 74Ge from the 72Ge(t,p) reaction

The reaction ⁷²Ge(t, p)⁷⁴Ge has been investigated with a 15 MeV triton beam. Fifty energy levels of ⁷⁴Ge were identified up to about 4.9 MeV excitation, eighteen of which were previously unreported. Angular distributions were measured and compared with DWBA calculations. Two low-lying states at 1.913 and 2.164 MeV have been assigned as J^π = 0⁺, corresponding to the 0₃⁺ and 0₄⁺ states in ⁷⁴Ge. The 4₂⁺ state has been located at 2.674 MeV, and the 2₄⁺ at 2.836 MeV. Many additional spin and parity assignments have been made. The ⁷⁴Ge nucleus shows a considerably different structure of 0⁺ states compared with the neighboring ⁷⁶Ge and ⁷⁸Ge nuclei, perhaps further evidence for the shape transition suggested recently for the Ge isotopes.     

The 27Al(t,p)29Al reaction at Et = 15 MeV

The ²⁷Al(t, p)²⁹Al reaction was studied at an incident energy of E_t = 15 MeV. Proton angular distributions were measured for the first 23 low-lying states. Comparisons of the data to DWBA calculations based on cluster-model and pure-configuration form factors were made which provided decompositions of the angular distributions into contributing L-values. Comparisons were also made to DWBA predictions based on microscopic amplitudes from a complete, sd-basis shell-model calculation.     

Observation of deuteron D-state and compound nucleus effects in (d,p) reactions on 46Ti and 52Cr with a polarized deuteron beam

The cross section and the vector and tensor analyzing powers have been measured for ⁴⁶Ti(d, p)⁴⁷Ti at deuteron energies of 6 and 10 MeV and ⁵²Cr(d, p)⁵³Cr at 6 MeV. Transitions were observed to the states at E_x=0.159, 1.549 and 1.793 MeV in ⁴⁷Ti and the states at E_x=0.0, 0.564, 1.006 and 2.321 MeV in ⁵³Cr. In addition, the cross sections and vector analyzing powers for deuteron elastic scattering were measured for the same targets and deuteron energies and compared to optical model calculations. The choice of optical parameters for the DWBA analysis of the (d, p) reactions is discussed. Calculations made with the DWBA method show that the deuteron D-state must be included to reproduce even qualitatively the (d, p) tensor analyzing power measurements. The j-dependence of the tensor analyzing power T₂₂ is discussed. The validity of the local energy approximation (which was used to incorporate the deuteron D-state into the DWBA calculations) is evaluated by comparison to finite range calculations. The contribution of compound nucleus reactions to the measured cross sections and analyzing powers was investigated. In order to determine the compound cross section, the Ericson fluctuations in excitation functions of cross section and vector analyzing power were measured from 5 to 7 MeV on each target. The formulas used to calculate the polarization observables from the Hauser-Feshbach theory are presented.