A. Graue

The 128Te(d, p) 129Te reaction at 7.5 MeV bombarding energy

Abstract The reaction 128 Te(d, p) 129 Te has been studied at 7.5 MeV bombarding energy by using the MIT broad-range, multiple-gap magnetic spectrograph. A total of 87 levels of 129 Te has been identified below an excitation energy of 4.7 MeV. The angular distributions of the protons were analysed in terms of zero-range, distorted-wave Born approximation calculations, and the orbital angular momentum of the transferred neutron was determined for 27 levels. Transition strengths were extracted and compared with pairing theory predictions. The ground-state wave function of 128 Te was found to be more complicated than expected from the simple shell model.

Nuclear reaction studies in the nickel isotopes: The 62Ni(d, p)63Ni and 64Ni(d, p)65Ni reactions

Abstract The reactions 62 Ni(d, p) 63 Ni and 64 Ni(d, p) 65 Ni have been studied at a bombarding energy of 7.5 MeV. With an energy resolution of approximately 13 keV, 78 levels in 63 Ni and 57 levels in 65 Ni were observed below 5.2 MeV and 4.7 MeV respectively. The angular distributions of the proton groups were measured for the majority of the levels and analyzed in terms of zero-range distorted-wave Born approximation calculations. Thus, information about the orbital angular momentum of the transferred neutrons and the spectroscopic strengths of the stripping levels were obtained. A sum-rule analysis was made for the 2 p 3 2 , 1 f 5 2 , 2p 1 2 and 1 g 9 2 single-particle states and the results compared with both shell-model predictions and recent pairing theory calculations. Levels whose angular distributions do not resemble any theoretical stripping curves are also discussed briefly, and some systematic trends in the level scheme of the odd Ni isotopes are mentioned.

A study of the 32S levels and the analogue levels of 32P by the 31P(3He, d)32S reaction

The 31P(3He, d)32S reaction has been studied with high resolution at 12 MeV bombarding energy. A detailed level scheme for 32S has been determined up to an excitation energy of 9.5 MeV revealing several previously unobserved states. The lp values and absolute spectroscopic factors extracted from a DWBA analysis of the experimental deuteron angular distributions have provided information on the wave functions for the T = 0 states as well as for the T = 1 isobaric analogue states of 32P. A comparison between the present data and those of previous experiments is made, and the results are discussed in terms of existing theoretical work in this mass region. Information on Coulomb displacement and symmetry energies is also extracted.

Energy-level structure of 131Te from the 130Te(d, p)131Te reaction

Abstract The 130 Te(d, p) 131 Te reaction induced by 7.5 MeV deuterons has been studied using the MIT broad-range multiple-gap spectrograph. More than 100 levels of 131 Te have been identified up to 5.8 MeV excitation energy. Angular distributions have been analysed using DWBA calculations. The number of holes in the neutron shell observed were 1.0 in 2 d 3 2 , 2.0 in 1 h 11 2 , 0.32 in 3 s 1 2 , and 0.12 in 2 d 5 2 , respectively. These results are in fairly good agreement with pairing theory predictions.

The 90Zr(d, p)91Zr reaction with high resolution

Abstract The 90 Zr(d, p) 91 Zr reaction has been studied at a bombarding energy of E d = 7.5 MeV with high resolution. A total of 89 levels of 91 Zr have been seen below E x = 6.5 MeV compared to the about 36 levels known previously in the same range. Complete angular distributions have been measured in a multiple-gap spectrograph for many of the transitions. A DWBA analysis has been carried out for those distributions showing stripping patterns. Spectroscopic factors, summed strengths, and single-particle energy centroids are deduced. The results are compared to other data on this nucleus.

A study of the 35Cl levels by means of the 34S(3He, d)35Cl reaction

Abstract The 34S(34He, d)35Cl reaction has been studied with high resolution at 11 MeV bombarding energy. A detailed level scheme for 35Cl has been determined up to an excitation energy of 5.8 MeV revealing several previously unobserved states. The lp values and absolute spectroscopic factors extracted from a DWBA analysis of the experimental deuteron angular distributions have provided information on the single proton character of the wave functions for the T = 1 2 states as well as for the lowest T = 3 3 isobaric analogue of the 35S ground state. A comparison between the present data and those of previous experiments is made and the results are discussed in terms of the existing shell-model and unified model calculations of this nucleus. Information on Coulomb displacement and symmetry energies is also extracted.

Nuclear structure studies in the tellurium isotopes: the 126Te(d, p)127Te reaction

Abstract The reaction 124Te(d, p)125Te has been studied at a bombarding energy of 7.5 MeV in order to get information about the 125Te nuclear level scheme. The protons were recorded simultaneously at 23 angles in a multiple-gap magnetic spectrograph. One hundred and fifty two levels were observed below an excitation energy of 6.2 MeV, and the proton angular distribution for 55 of these transitions were compared to DWBA calculations in order to determine the transferred orbital angular momentum, ln, and to measure spectroscopic factors. The lower part of the level scheme was compared to the results from studies of 125Sb decay, and to theoretical pairing-theory calculations. A sum-rule analysis of the holes in the 50–82 neutron shell gave 7.95 vacancies while the expected value is 10. Single-quasiparticle energies for 125Te, 127Te, 129Te and 131Te are listed. A comparison is made with the isobaric analogue states in 125I observed elsewhere in the 124Te(p, p) reaction.

Study of (d, p) reactions on even tellurium nuclei: The 122Te(d, p)123Te reaction

Abstract The energy levels of 123 Te have been studied in the 122 Te(d, p) 123 Te reaction at 7.5 MeV bombarding energy using the MIT multiple-gap magnetic spectrograph. More than one hundred levels were observed up to 5.5 MeV excitation energy. Angular distributions were measured and l -assignments given for 32 of the stronger proton groups. The level scheme was compared to results from IAR and radioactive decay studies. A new 1 2 + level was observed at 600 keV. A DWBA analysis was used to obtain spectroscopic amplitudes for orbits in the 50–82 neutron shell. Following standard prescriptions a comparative analysis of the data from the five reactions A Te(d, p) A + 1 Te, A = 122, 124, 126, 128, 130 was performed and pairing model parameters were extracted. The obtained information indicates that the constant pairing strength approximation is reasonable for the 50–82 neutron orbits in tellurium nuclei.

The 207Pb(d, p)208Pb reaction with high resolution

Abstract The reaction 207Pb(d, p)208Pb has been studied at Ed = 18.0 MeV using the MPI Heidelberg Emperor tandem accelerator and multiple-gap spectrograph. The average resolution of 18 keV was better than previous measurements, and this, combined with the long beam exposure, allowed many finer details of the neutron particle-hole structure of 208Pb to be examined. In all, 45 levels were seen up to Ex = 6.3 MeV, many of which had never been seen before. A DWBA analysis of the stripping transitions angular distributions is made, and values of (2J + 1)Sij, energy centroids, and summed strengths are given. An interesting cluster of 1i 11 2 and 2g 9 2 levels at Ex ≈ 4.2 MeV are resolved and are compared to recent isobaric analog state data. A search for weak stripping strength to known pairing vibrations in 208Pb gave essentially negative results and points to the need for improved ultra-resolution measurements.

The nuclear structure of 178Hf studied by the 181Ta(p, α)178Hf reaction

Abstract The microscopic structures of levels in 178 Hf have been studied by the 181 Ta(p, α) reaction using 17 MeV protons. The reaction products were analyzed with a magnetic spectrograph and detected with photographic emulsions, yielding an overall resolution of ⩽ 20 keV (FWHM). Levels with significant populations must involve a proton in the 7 2 + [404] Nilsson orbital, which forms the ground state of the 181 Ta target nucleus. The admixtures of various two-quasiproton configurations were extracted from the observed cross sections. The ground-state band is populated unusually weakly, while a large 7 2 + [404] − 7 2 + [404] strength is observed for the K π = 0 + band at 1199 keV. This is attributed to the irregular filling of Nilsson proton states in this region, whereby the 7 2 + [404] orbital appears as the ground state for tantalum as well as lutetium nuclei. For the well-known K π = 8 − bands at 1147 and 1479 keV the present results confirm in a direct manner the 9 2 − [514] π + 7 2 + [404] π admixtures proposed earlier on the basis of gamma-ray mixing ratios and log ft values. An upper limit of ∼ 5% for the 9 2 − [514] π − 7 2 + [404] π configuration in the K π = 1 − band at 1310 keV is consistent with earlier proposals that this is predominantly a 9 2 + [624] v − 7 2 − [514] v two-quasineutron band. A new K π = 1 − band has been assigned at 1513 keV, which has the main 9 2 − [514] π − 7 2 + [404] π strength. Levels previously assigned as a K π = 2 − band at 1566 keV are shown to be rotational excitations based on this new K π = 1 − band. The K π = 3 + band at 1758 keV is found to be predominantly the 7 2 + [404] π − 1 2 + [411] π configuration, while the strength for the K π = 4 + parallel coupling of the same two protons is spread over more than one band.