R.A. Emigh

The (3He, n) reaction on tellurium isotopes

Abstract The 122, 124, 125, 126, 128, 130Te(3He, n) reactions have been studied at an incident energy of 25.4 MeV using the University of Colorado 9 m neutron time-of-flight facility. Angular distributions of neutrons have been measured for all targets over the angular range 0°–22°. In addition to the ground state transitions relatively strong L = 0 transitions to excited levels in the region of 2.0 MeV are observed in all residual nuclei. The experimental results are compared to zero-range DWBA predictions. Pairing model calculations are able to account for the strongly excited low-lying Jπ = 0+ states observed.

The (3He, n) reaction on N = 82 targets and even isotopes of neodymium

Abstract Angular distributions of neutrons from the ( 3 He, n) reaction were measured at 25.4 MeV over the angular range 0°–22° for the N = 82 targets 136 Xe, 138 Ba, 139 La, 142 Nd and 144 Sm. In addition, measurements were carried out for the targets 144, 146, 148, 150 Nd spanning the transition from spherical to permanently deformed ground states. For each even A , N = 82 target, transitions to excited states were observed with considerable L = 0 and L = 2 strength. Weak transitions to excited states were observed for the 144 Nd and 139 La targets. Only the ground state transition was observed for the other targets. A careful search was made for the 0 + vibrational states excited in the (t, p) reaction at 0.747 MeV in 150 Sm and 0.686 MeV in 152 Sm, but these were not populated with measurable strength in the ( 3 He, n) reaction. The Q -value for the 144 Sm( 3 He, n) 146 Gd(g.s.) reaction was measured to be 0.977±0.030 MeV, yielding a ground state mass of 145.91832±0.00003 amu for 146 Gd.

A study of the 99Tc(p, d)98Tc reaction

Abstract The energy levels of 98Tc were studied with the 99Tc(p, d)98Tc reaction at a bombarding energy of 22.9 MeV and 15 keV resolution (FWHM). The Q-value for this reaction was found to be −6.755 ± 0.009 MeV and the 98Tc mass excess was calculated to be −86.421 ± 0.011 MeV. This reaction provided the excitation energies for 49 neutron hole states below 1.5 MeV excitation. Comparison of experimental angular distributions with DWBA calculations permitted assignment of lf-values and the extraction of spectroscopic factors for 44 of these levels. Extensive configuration mixing is observed except in the low-lying multiplet. Effective proton-particle, neutron-hole interaction matrix elements were obtained from the low-lying positive-parity multiplet of 98Tc.

Single-nucleon transfer reactions to 100Ru

Abstract Proton stripping and neutron pickup reactions have been studied to the levels of 100Ru, a nucleus with collective properties that have been thoroughly studied. The neutron pickup results are consistent with a calculation for the neutron-hole structure of the Jπ = 2+ phonon state. The proton stripping results show no resemblance to either the phonon structure calculation or to the prediction of a shell model with good seniority. Strong proton excitation of the known 8+ state at 3.06 MeV shows that this is not the four-boson state predicted by the ⊙IBA at that excitation.

Neutron-hole states in 204Tl

Abstract The level scheme of the doubly odd nucleus 204Tl has been studied via the 205Tl(p, d)204Tl reaction at an incident energy of 26.1 MeV and with an energy resolution of better than 10 keV (FWHM). Seventy-seven levels are observed below 3.2 MeV excitation. The extraction of l-transfers and spectroscopic factors for most levels was accomplished by the comparison of experimental angular distributions with DWBA calculations. Extensive configuration mixing is implied from the large number of levels populated. The state at 1.289 MeV, which is populated via l = 6 transfer, is most likely the 6+ level. This knowledge and the known location of the 7+ isomer at 1.103 MeV completes the experimental determination of the doublet involving the π3 s 1 2 and v li 13 2 orbitals.

The 85Rb(p, d)84Rb reaction

Abstract The spectrum seen in single neutron pickup leading to the doubly odd nucleus 84Rb is remarkably clean, with only five levels populated by l = 4 and six by l = 1 transitions. A simple 2J+1 weighting for the l = 4 data, combined with previous information on 84Rb, allowed the Jπ = 2−–7− states of the ( v g 9 2 −3 ⊗ π f 5 2 −3 ) multiplet to be identified. These data are used to determine the two-hole π f 5 2 −1 -v g 9 2 − interaction matrix elements.