γ-decay of the deeply-bound hole states in 101Pd, 105Pd, 107Pd, 111Sn, 117Sn observed in the (3He, αγ) reaction at 70 MeV

The γ-decay of deep-hole states in ^{101, 105, 107}Pd was studied via the (³He, αγ) reaction at E_³he = 70 MeV and supplemented by data from ^{112, 118}Sn targets to investigate the deep-hole spreading mechanism. The γ-decay pattern for the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ deep-hole state shows a strong dependence on the spreading width: if the deep-hole state is observed as a sharp peak, it mainly decays to the low-lying $\text{7}\text{2}{}^{\mathrm{+}}$ state by a spin-flip M1 transition with a large M1-E2 mixing ratio; if the deep-hole state is observed as a broad bump, it decays statistically indicating the complete spreading of the hole strength over the underlying states; if the deep-hole state is observed with a structure intermediate between a sharp peak and broad bump, its γ-decay shows both decay patterns.A sharp peak at E_x = 2.396 MeV in ¹⁰¹Pd which carries a large fraction of the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ hole strength (C²S = 2.0) was found to be a single state having a width of less than 2.5 keV.For the spin-flip M1 transition the destructive interference between the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ component and the coupled components of the deep-hole state was found in heavily spread states.A quasiparticle-plus-rotor (QPR) model was applied to calculate the fragmentation in the doorway stage for the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ neutron deep-hole state in the Pd isotopes. A reasonable agreement between the calculation and the experimental results was obtained for the strength fragmentation, for the nucleus ¹⁰¹Pd. However, the large M1-E2 mixing ratio experimentally observed was not reproduced.     

The 116Sn(d,t)115Sn reaction at 23 MeV

The levels of ¹¹⁵Sn up to 4 MeV excitation energy have been studied with 15–18 keV energy resolution, and many previously unreported levels have been observed. Angular momentum transfers and spectroscopic factors have been determined for most of the levels up to 3 MeV. The main features of the observed fragmentation of the strength are rather well reproduced by means of a weak coupling calculation.     

Proton occupancies in the even Se ground states via the (d, 3He) reaction

The spectroscopic factors for the levels of^{73,75,77,79,81}As have been measured in the Se(d, ³He)As reactions at 25.2 MeV. The proton occupation numbers deduced for the even Se isotopes show that the striking change in proton configuration, observed for the Ge isotopes between N ? 40 and N ? 42, does persist for the Se isotopes. This change is not reproduced, either by a model calculation using spectral distribution methods or by proton wave functions recently suggested for the Se isotopes to explain the results of the Se(d, ⁶Li)Ge reactions.     

Cross sections for 197Au(n, γ)198Au and 115In(n, γ)116mIn in the neutron energy region 2.0–7.7 MeV

The cross sections for the reactions ¹⁹⁷Au(n, γ)¹⁹⁸Au and ¹¹⁵In(n, γ)^116mIn have been measured with the activation method in the neutron energy region 2.0–7.7 MeV. The influence of background neutrons on the results was studied in considerable detail. The main problems are caused by low-energy neutrons produced by charged-particle reactions in the target material and secondary neutrons from nonelastic reactions in the sample and surrounding materials.The measured capture cross sections are generally lower than previous results and the deviation tends to increase with increasing neutron energy. The data are also compared with calculations based on the compound-nucleus model and quite good agreement is obtained.     

Multiple scattering effects for quasifree scattering in 3He(d,dd)1H breakup reaction

The differential cross sections for the ³He(d, dd)¹H breakup reaction have been measured in the kinematical region corresponding to quasifree scattering (QFS). The angular dependence of the cross section at the minimum laboratory energy of the unobserved proton has been obtained. The shapes of energy spectra are approximately reproduced by a calculation in the plane-wave impulse approximation (PWIA). As for the angular dependence of the cross section and for the absolute values, the calculation fails to reproduce the experimental results. A calculation with multiple scattering effects reproduces the experimental data well, not only for the shape of the energy spectra but also for the angular dependence. For the absolute cross sections, the ratio of the experimental values to the calculated ones with multiple scattering effects is 0.7 and this value is improved compared with the value of 0.3 obtained by the PWIA calculation.     

Two-step processes in the 40Ca(α, 3He)41Ca reaction

The ⁴⁰Ca(α, ³He) reaction has been studied at 36 MeV incident energy. About fifty levels have been observed up to 7.1 MeV excitation energy and angular distributions were measured from 6–60° using a split-pole spectrometer. A local zero-range DWBA analysis has been carried out, and the deduced l-assignments and spectroscopic factors are compared with those obtained from previous neutron stripping experiments. Core-excited states in ⁴¹Ca with a [3^? ? f_7,2], [2⁺ ? f_7,2] and [5^? ? f_7,2] component previously observed in inelastic scattering experiments, are selectively excited by the (α, ³He) reaction. Their angular distributions are compared with coupled-reaction-channel calculations, assuming a pure two-step reaction mechanism. The agreement between theory and experiment may be considered as rather satisfactory for a number of levels. In particular the $\text{1}\text{2}{}^{\mathrm{+}}\text{and}\text{3}\text{2}{}^{\mathrm{+}}$ levels and the high-spin states with $\text{J}{}^{\mathrm{\pi }}\text{=}\text{9}\text{2}{}^{\mathrm{?}}\text{,}\text{11}\text{2}{}^{\mathrm{+}}\text{,}\text{15}\text{2}{}^{\mathrm{+}}\text{and}\text{17}\text{2}{}^{\mathrm{+}}$ are successfully described within the framework of the weak-coupling model.     

Investigation of states in 30P via the 30Si(3He,t)30P reaction at 30 MeV

The ³⁰Si(³⁰He, t)³⁰P reaction has been measured for about 100 levels in ³⁰P with E_x < 8.8 MeV. Little selectivity in the population of states has been observed. For 75 levels angular distributions have been analysed using a “fingerprint method” by determining the L-value from a comparison in shape with transitions to states with known J^π. For possible mixed L-transitions a dominance of the higher L-value is observed for almost all cases. Coulomb displacement energy calculations utilizing shell-model wave functions have been used to identify T = 1 states.     

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.     

A study of 50V using the direct reactions 49Ti (3He,d) and 51V(d,t)

Energy levels in ⁵⁰V up to 4.3 MeV have been studied using the ⁴⁹Ti(³He, d)⁵⁰V and ⁵¹V(d,t)⁵⁰V reactions with ³He particles of 22 MeV and deuterons of 19.5 MeV incident energy. More than eighty levels are seen, with angular distributions taken for forty-one levels in the (³He, d) reaction and for the ten lowest levels in the (d, t) reaction. The angular distributions are compared with the distorted-wave Born approximation (DWBA) to extract the l-values of the transferred nucleons and obtain the spectroscopic strengths. In the stripping reaction, a small amount of l = 0 and l = 2 strength is seen, indicating the presence of s and d proton holes in the g.s. of ⁴⁹Ti. The results are compared with a recent shell-model calculation based on an $\text{(}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{n}}$ configuration, and show qualitative agreement.     

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.     

The reaction 14C(3He,n)16O and the coexistence model of 16O

The reaction ¹⁴C(³He, n)¹⁶O has been measured at a ³He bombarding energy of 25.4 MeV. The zero-degree differential cross section for the excitation of the three low lying 0⁺T = 0 states, at energies 0.0, 6.05 and 12.05 MeV are, respectively, 1.33 ± 0.10, 0.49 ± 0.10, and 0.50 ± 0.10 mb/sr These measured cross sections are in rough agreement with single-step zero-range DWBA calculations using an empirically determined ¹⁴C ground state wave function and in which the Brown and Green coexistence-model wave functions are used to describe the ¹⁶O 0⁺ states. The angular distribution of the transition to the ground state is measured between 0° and 32°.     

Study of 20Ne(3He,n)22Mg at 3He energies between 2.6 and 4.0 MeV

The ²⁰Ne(³He, n) reaction leading to the ground state of ²²Mg has been investigated in the ³He⁺ energy range of 2.6 to 4.0 MeV. Angular distributions were determined with a neutron time-of-flight spectrometer at average incident energies (lab) of 3.27, 3.69, and 4.01 MeV between 0° and 120° (lab). Excitation functions for the energy region were measured at 0° and 80° (lab). The observed differential cross sections are explained by coherent contributions from direct interaction and compound-nucleus formation. A spectroscopic factor was extracted for the DWBA calculation from the absolute cross-section measurements and found to be $\text{? = 0.43±0.21}$. Resonances in the compound-nucleus formation were found at 3.00 and 3.33 MeV (c.m.) with widths of 0.28 and 0.21 MeV and spins of $\text{5}\text{2}{}^{\mathrm{+}}\text{and}\text{1}\text{2}{}^{\mathrm{?}}$, respectively.     

Level structure of123, 125I from the 122, 124Te(3He,d) reactions

The energy levels of ¹²³I and ¹²⁵I have been studied in the ^{122, 124}Te(³He, d)^{123, 125}I reactions at 24 MeV bombarding energy. The reaction products were analysed with an Enge split-pole magnetic spectrograph. A total of 57 levels below 3.3 MeV in ¹²³I and 79 levels below 4.1 MeV in ¹²⁵I were observed. Angular distributions were measured and compared with DWBA calculations to obtain orbital angular momentum transfers and spectroscopic strengths. The results were compared to previous radioactive decay studies and to theoretical energy level calculations.     

The reaction 3He + p → p + p + d studied with BOL at 69 MeV 3He incoming energy

The proton-induced ³He breakup into p and d has been studied in a kinematically complete way at 69 MeV ³He-incoming (23 MeV p-incoming) lab energy, using the spherical multi-detector array BOL.The four-dimensional cross-section data cover most of the three-body final-state phase space. By slicing and integrating the data, they have been brought into suitable one- and two-dimensional representations to reveal different aspects of the reaction process. Based on these, this paper presents information on the interplay between the different reaction modes occurring in the p³He breakup process. In particular, pp final-state interaction, pp and pd quasi-free scattering and nucléon transfer have been studied here.Anomalous effects, probably due to interference between these processes, show up in the data.     

16O Induced reactions on 116Sn at 64 MeV

Angular distributions have been measured for the elastic and inelastic scattering of 64 MeV ¹⁶O ions on ¹¹⁶Sn targets and analysed through coupled-equation calculations. The one-proton transfer has also been studied and the DWBA analysis gives results consistent with those derived from (³He, d). The two-proton transfer has been analysed in the framework of both DWBA and CCBA; theoretical wave functions for Te isotopes have been tested and the importance of multistep processes is discussed.     

Elastic electron scattering from 3He and 4He

The cross sections for elastic electron scattering from ³He and ⁴He were measured for the momentum transfer range from 0.45–2.0 fm^?1. The cross sections were separated into their longitudinal (charge) and transverse (magnetic) contributions using the Rosenbluth formula. The charge and magnetic form factors were obtained model-independently.The rms charge radii were found to be 1.671 (14) fm for ⁴He and 1.976 (15) fm for ³He, and the magnetic rms radius of ³He is 1.99 (6) fm. The mis charge radius for ⁴He is in excellent agreement with the latest muonic data.Comparison of the form factors was made with Faddeev three-body calculations using realistic two-body NN interactions. At present the theoretical calculation is not able to reproduce the experimental data.     

(γ, γ′) reactions in 89Y, 115In and 197Au at intermediate energies

The yields of isomeric states in ⁸⁹Y, ¹¹⁵In and ¹⁹⁷Au produced by the (γ, γ') reaction have been measured in the energy range 100–800 MeV by the activation method. From the yields the cross sections have been deduced. Large cross sections around the first pion resonance are found. The experimental results are compared to calculations based on the impulse approximation.     

A study of the 14C(6Li, 6He)14N reaction at 93 MeV

The reaction ¹⁴C(⁶Li, ⁶He)¹⁴N was investigated with 93 MeV ⁶Li ions in an angular interval of 7–26°. Angular distributions were analysed for the four most intense groups of ⁶He nuclei, corresponding to transitions to the ground (1₁⁺) and the excited (1₂⁺, 2₁^?, 4₁^?) states of ¹⁴N. In the theoretical analysis a mechanism of the spin-isospin excitation was suggested in the DWBA frame with the finite range of interaction and recoil in the light system (⁶Li⁶He) taken into account. In the calculations both shell-model wave functions and transition densities obtained in the theory of finite Fermi systems (FFS) were used. From the comparison between theory and experiment the Landau-Migdal force constant g′ is estimated in order to obtain some information on the degree of nuclear proximity to the threshold of pion condensation.     

Deuteron d-state effects for the reactions 117Sn(d, p)118Sn and 119Sn(d, p)120Sn

Angular distributions of the differential cross section and the three tensor analyzing powers were measured for the reactions ¹¹⁷Sn($\text{d}$, p)¹¹⁸Sn and ¹¹⁹Sn($\text{d}$, p)¹²⁰Sn at E_d = 12 MeV. In addition, excitation functions of the tensor analyzing power T₂₀ were measured at proton lab angles of 0° and 5° for energies ranging from 10 to 12 MeV. At forward angles, the tensor analyzing powers for the ground state (l_n = 0) transitions are more than an order of magnitude larger than the predictions of distorted-wave calculations which neglect the deuteron D-state. Qualitative agreement with the measurements is obtained when the D-state is included.     

Response functions of 58Ni, 116Sn AND 208Pb to the excitation of intermediate-energy α-particles

Inelastic scattering of 340 MeV and 480 MeV α-particles has been measured on ⁵⁸Ni, ¹¹⁶Sn and ²⁰⁸Pb up to 60 MeV excitation energy. Consistent background subtraction and multipole analysis has provided the repartition of multipole strength for all three nuclei. The so-obtained response functions show the already known low-energy giant resonances in a detailed way, as well as new giant resonances at high energy.