[en] Gamma rays with energies up to 21 MeV were measured with Ge detectors. Such γ rays were produced in the 208Pb(p,γ)209Bi reaction. The position of the 2g9/2 single proton orbit in 209Bi has been determined indicating the size of the Z=126 shell gap

[en] The ⁸⁶Kr+²³⁸U reaction has been studied at krypton beam energies about 30 MeV above the Coulomb barrier. Reaction products were detected by an array of 32 photovoltaic cells coupled to the AFRODITE γ-ray detector array at iThemba LABS. A symmetric fission component has been observed at about 600 MeV total kinetic energy. This could possibly be due to fusion-fission with a cross section of 35±20 mb

No abstract available

[en] An assembly for a commercial Ga"+ liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga"+ ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga"+ and Au"+ ion beams will be reported as well

[en] Excited states in ¹⁶⁷Ta, populated in the ¹⁴¹Pr(³⁰Si,4n)¹⁶⁷Ta reaction, have been studied using the NORDBALL Ge detector array. For the πh_11/2[514]9/2^- decay sequence, strong signature-dependent effects in the transition quadrupole moment ratio, Q₁(I→I-1)/Q₂(I→I-2), have been observed over the spin range 21/2≤I≤39/2 which encompasses a BC neutron alignment. This is interpreted as strong evidence for departure from axial symmetry

[en] In intermediate-mass systems, collective excitations of the target and projectile can greatly enhance the subbarrier capture cross section σ_cap by giving rise to a distribution of Coulomb barriers. For such systems, capture essentially leads directly to fusion [formation of a compound nucleus (CN)], which then decays through the emission of light particles (neutrons, protons, and alpha particles). Thus, the evaporation-residue (ER) cross section is essentially equal to σ_cap. For heavier systems, the experimental situation is significantly more complicated owing to the presence of quasifission (QF) (rapid separation into two fragments before the CN is formed) and by fusion-fission (FF) of the CN itself. Thus, three cross sections need to be measured in order to evaluate σ_cap. Although the ER essentially recoil along the beam direction, QF and FF fragments are scattered to all angles and require the measurement of angular distributions in order to obtain the excitation function and barrier distribution for capture. Two other approaches to this problem exist. If QF is not important, one can still measure just the ER cross section and try to reconstruct the corresponding σ_cap through use of an evaporation-model code that takes account of the FF degree of freedom. Some earlier results on σ_cap obtained in this way will be reanalyzed with detailed coupled-channels calculations, and the 'extra-push' phenomenon discussed. One may also try to obtain σ_cap by exploiting unitarity, that is, by measuring instead the flux of particles corresponding to quasielastic (QE) scattering from the Coulomb barrier. Some new QE results obtained for the ⁸⁶Kr + ²⁰⁸Pb system at iThemba LABS in South Africa will be presented

[en] A summary of recent results of research at iThemba LABS is given. This includes high-resolution measurements of the fine structure of isoscalar giant quadrupole resonances, a new programme to measure fusion barrier distributions for reactions leading to the formation of superheavy elements, measurements of high-energy γ-rays from (p,γ) reactions using the AFRODITE array of HpGe clover detectors, and a comparison of the vibrational band structures of ¹⁶⁰Yb, measured with the AFRODITE array, with the X(5)-β²ⁿ model. A summary of future developments is given

[en] A complete kinematic measurement of the ⁶Li(³He,³H)αpp reaction is performed at E_lab=50 MeV, to investigate the cluster structure of ⁶Be. The energy and angular distributions of the breakup particles, emitted from the ground and first excited states of ⁶Be, are compared to three-body resonance and two-body sequential decay calculations. The results indicate a rather pure three-body configuration of the 2⁺ state of ⁶Be but they are not conclusive regarding the decay mode of the 0⁺ state. No branching ratio between sequential and three-body decay paths could be extracted. Excitations above the 2⁺ state were populated at E_x=1.67-23 MeV. Decay through ⁵Li-p and ²He-⁴He channels is identified in the continuum of ⁶Be, and the reaction mechanism is discussed.

[en] Negative-parity bands in the vicinity of ¹⁵⁶Gd and ¹⁶⁰Yb have been suggested as candidates for the rotation of tetrahedral nuclei. We report the observation of the odd and even-spin members of the lowest energy negative-parity bands in ¹⁶⁰Yb and ¹⁵⁴Gd. The properties of these bands are similar to the proposed tetrahedral band of ¹⁵⁶Gd and its even-spin partner. Band-mixing calculations are performed and absolute and relative quadrupole moments deduced for ¹⁶⁰Yb and ¹⁵⁴Gd. The values are inconsistent with zero, as required for tetrahedral shape, and the bands are interpreted as octupole vibrational bands. The failure to observe the in-band E2 transitions of the bands at low spins can be understood using the measured B(E1) and B(E2) values.

[en] Incomplete-fusion reactions have been used to study high-spin states in ¹⁷¹Tm. Gamma rays and conversion electrons were measured using pulsed-beam conditions for enhanced isomer sensitivity. A K^π=19/2⁺, three-quasiparticle isomer was identified, with a half-life of 1.7(2)μs. The faster than expected transition rates from the isomer can be understood as being due to a chance near-degeneracy, with mixing between the isomeric state and the I^π=19/2⁺ member of the one-quasiparticle rotational band to which it decays. The implied mixing matrix element is 12(2) eV.