The (3He,n) reaction on 16O and 18O

The (³He, n) reaction on ¹⁶O and ¹⁸O has been used to study low-spin states in ¹⁸Ne and ²⁰Ne up to E_x ≈ 8 and 20 MeV, respectively. The measured neutron angular distributions have been analysed using DWBA. By a comparison with shell-model calculations in the (s, d) shell it is found that most of the two-proton transfer strength can be explained within that shell. Important contributions, however, from the (f, p) shell in low-lying negative parity states are also present.     

Evidence for inelastic processes in the 24Mg(13C, 12C)25Mg reaction at elab = 30 MeV

The ²⁴Mg(¹³C, ¹²C)²⁵Mg reaction has been studied at 30 MeV using a magnetic spectrometer. Differential cross sections for transitions to several final states in ²⁵Mg have been measured and analysed using an exact finite range DWBA code. The DWBA predictions have fitted the bell-shaped distributions satisfactorily, yielding spectroscopic factors which are in reasonable agreement with those obtained using (d, p) reactions. The exceptions are the $\text{3}\text{2}$⁺ state at 0.97 MeV which displays a marked departure from the bell-shaped angular distribution obtained for the other $\text{3}\text{2}$⁺ state at 2.80 MeV, and the $\text{7}\text{2}$⁺ state at 1.61 MeV whose angular distribution has an unusual shape, displaying a deep minimum located at the grazing angle. A semiquantitative model has been used to suggest that the angular distribution for the 0.97 MeV state is evidence for the coupling of inelastic processes in this transition. In the case of the 1.61 MeV state it is suggested that the angular distribution shows the influence of indirect Coulomb excitation on the transfer cross sections.     

The (d, 6Li) reaction on 24Mg, 26Mg and 28Si at 35 MeV

Data for the (d, ⁶Li) reaction on targets of ²⁴Mg, ²⁶Mg and ²⁸Si have been obtained at 35 MeV bombarding energy. Angular distributions were measured for low-lying states in the residual nuclei. Zero-range distorted-wave Born approximation (DWBA) calculations have been used to analyze the data. The DWBA calculations account for the shapes of the experimental distributions reasonably well. The observation of significant population of unnatural parity states implies, however, that other transfer mechanisms may be important. The experimental spectroscopic factors are in qualitative agreement with those obtained from SU(3) theory.     

Spectroscopy of A = 16 from 13C(6Li,t)16O

The ¹³C(⁶Li, t)¹⁶O reaction has been studied at 34 MeV. Selective population of narrow states is observed up to 21 MeV excitation in ¹⁶O. This reaction populates strongly both unnatural-and natural-parity states that have little or no ¹²C + α₀ width. The measured angular distributions are compared with Hauser-Feshbach and finite-range DWBA calculations. Reasonable agreement with the DWBA calculations is found for most of the states strongly populated. The widths of the narrow states populated in the 16–20 MeV excitation region are presented. Comparison of the present data with that from medium-energy inelastic scattering and other multiparticle transfer reactions is made.     

Study of 59Cu by means of 58Ni(d,n)

The reaction ⁵⁸Ni(d, n)⁵⁹Cu has been studied at 7.0 MeV bombarding energy. Angular distributions of transitions to 16 states in ⁵⁹Cu have been extracted and analysed with DWBA to yield absolute spectroscopic strengths. The results are compared to those of other measurements.     

Heavy-ion reactions on 26Mg

Reactions induced by 126 MeV ¹⁶O ions on ²⁶Mg have been investigated in the angular range 5° to 12°. Optical model parameters were derived from the elastic scattering data and were used in a DWBA analysis of the inelastic scattering and single-nucleon transfer data. Satisfactory agreement was obtained for the angular distributions and for the spectroscopic factors. The two-nucleon transfer reactions appear to excite vibrational states. A DWBA analysis correctly describes the angular distributions for the two-proton transfer data. Most of the other few-nucleon transfer spectra exhibit little selective excitation but give a maximum at an energy consistent with the optimum Q-value predicte for direct transfer. Both the one- and twonucleon transfer data require that the ²⁶Mg ground state contains considerable (λ, μ) = (4. 8) components and is not pure (10, 2) as predicted by simple SU(3) calculations.     

Energy dependence of multinucleon transfer reactions induced by 20Ne on 12C

The energy dependence of up to five nucleon transfer reactions induced by ²⁰Ne on ¹²C has been measured in the energy range 150 to 294 MeV. Good agreement is found between the experiment and both DWBA and semiclassical calculations.     

Unexpected interference patterns observed in the 12C(14N, 13N)13C reaction at energies close to the Coulomb barrier

The reaction ¹²C(¹⁴N, ¹³N)¹³C has been measured at 28, 32, 34 and 36 MeV beam energies. The energy dependence of the measured interference pattern cannot be reproduced by DWBA calculations which take account of the interference between proton and neutron transfer. A rather strong asymmetry of the angular distributions about θ_c.m. = 90° has been observed.     

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.     

The 4He(p,d)3He reaction at 770 MeV

The differential cross section of the ⁴He(p, d)³He pick-up reaction has been measured at E_p = 770 MeV. The data are analysed in the framework of the DWBA; both one-nucleon and one-N¹ transfers are considered.     

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.     

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.     

The 26Mg(14N, 10B)30Si and 26Mg(14N, 11B)29Si reactions

Reactions induced by ¹⁴N on ²⁶Mg at bombarding energies of 60–95 MeV have been studied. Angular distributions for states populated in ²⁹Si by the (¹⁴N, ¹¹B) reaction and in ³⁰Si by the (¹⁴N, ¹⁰B) reaction have been compared with Hauser-Feshbach and DWBA calculations to determine the reaction mechanism and to deduce spectroscopic information. The cross sections for the states populated in ²⁹Si and ³⁰Si are in poor agreement with statistical model calculations, indicating a non-compound nucleus mechanism.     

Study of (d, α) reactions on 94Zr and 96Zr

The nuclear structure of ⁹²Y and ⁹⁴Y has been investigated by the (d, α) reaction on ⁹⁴Zr and ⁹⁶Zr with 11.5 MeV deuterons. Some new levels have been seen in ⁹²Y and ⁹⁴Y. The angular distributions for these levels have been measured. A zero-range DWBA analysis has been carried out for these distributions and spin-parity assignments have been made for the new levels.     

Transfer reactions induced by 17, 18O on 12, 13C at c.m. energies between 12.6 TO 14.0 MeV

Angular distributions for one-neutron and many-nucleon transfer reactions were measured in the systems ^{17, 18}O and ^{12, 13}C at c.m. energies between 12.6 to 14.0 MeV. All the cross sections were analyzed in terms of the full-recoil finite-range DWBA model. For multi-nucleon transfer processes an inert cluster transfer was assumed. The sensitivity of DWBA calculations to various parameter sets is discussed, and the effect of the no-recoil approximation on the phase and magnitude of the transfer amplitude is studied. For one-neutron transfer reactions the forward part of the angular distributions was reproduced reasonably well by the DWBA model, yielding satisfactory spectroscopic information. The rise of the cross section at the backward angles was not reproduced by the DWBA model. Possible contributions of cluster-exchange and compound-nucleus reactions are discussed. For multi-nucleon transfer reactions poorer fits were obtained, particularly in the ¹⁸O+¹²C system.     

The reaction 16O(6Li,d)20Ne at 75 MeV

The angular distributions of the reaction ¹⁶O(⁶Li, d)²⁰Ne at 75 MeV for transitions to members of the ground state band are well fitted by exact finite-range DWBA calculations assuming a direct α-cluster transfer and yield spectroscopic factors in good agreement with shell-model predictions.     

Three-nucleon transfer on 12C: The 12C(α, p)15N reaction at 96.8 MeV

Angular distributions of protons from the ¹²C(α, p)¹⁵N reaction have been measured over the angular range from 10–70° at an α-particle bombarding energy of 96.8 MeV. Well defined particle groups are observed up to an excitation energy of 18 MeV in ¹⁵N. The relatively small number of states excited implies a selectivity both in the reaction mechanism and in structure effects. DWBA calculations using a semi-microscopic three-nucleon form factor have been performed using several different sets of wave functions. Good agreement in the ratio σ_exp/σ_th is obtained for most states using the ¹⁵N wave functions of de Meijer. The strongest state in the (α, p) spectrum is observed at 15.397 MeV in ¹⁵N and DWBA calculations give good agreement for a $\text{13}\text{2}{}^{\mathrm{+}}$ assignment. This state has been observed only in other three-nucleon transfer reactions involving heavy ions. The recent discovery of a $\text{9}\text{2}{}^{\mathrm{+}}$ state at 10.693 MeV in a p+¹⁴C resonance measurement is supported by our analysis.     

The (t, α) reaction on 121Sb and 123Sb

Angular distributions of α-particles from the (t, α) reaction on ¹²¹Sb and ¹²³Sb have been measured for incident tritons of 12 MeV. Levels up to excitation energies of 5.2 and 4.9 MeV in ¹²⁰Sn and ¹²²Sn, respectively, have been identified and analysed by the DWBA. Values of orbital angular momenta of the transferred protons have been assigned and spectroscopic factors deduced for all strongly excited levels. The extracted ground-state wave functions of the target nuclei have been compared with the calculated ones. A mixture of collective degrees of freedom is present in the low-lying states, weakly excited by the above very selective proton pick-up reaction. These states are populated by the pick-up of external protons (outer shells). At higher excitation energy (between 4 and 5 MeV) there are many strongly excited states populated by the proton pick-up from the Z = 50 proton core (inner shells); a predominantly 1p-1h character has been assigned to these states.     

Study of low-lying levels in 47Ca with the 48Ca(d, t)47Ca reaction

Angular distributions of cross sections [α(θ)] and vector analyzing powers [iT₁₁(γ)] have been measured for seven low-lying states or groups of states excited by the ⁴⁸Ca($\text{d}$, t)⁴⁷Ca reaction with 13.5 MeV deuterons and analyzed by the DWBA. On the basis of comparison of vector analyzing powers with DWBA calculations, spin-parity assignments have been made or confirmed for several states. Spectroscopic factors have been extracted. Angular distributions for weak states at 3.30 and 3.57 MeV excitation in ⁴⁷Ca could not be reproduced by DWBA calculations. Investigations of compound nucleus and multi-step contributions to the cross sections and analyzing powers for these states have been made by means of Hauser-Feshbach and CCBA calculations. Optical model parameters were obtained from analysis of 13.5 MeV deuteron elastic scattering cross sections and analyzing powers.