Determination of the k 0-values for 75Se, 110mAg, 115Cd–115mIn, 131Ba, and 153Sm by irradiation in highly thermalized neutron flux

The k ₀-values were determined for five high Q ₀(n,γ) reactions, including ⁷⁴Se(n,γ) ⁷⁵Se, ¹⁰⁹Ag(n,γ) ^110mAg, ¹¹⁴Cd(n,γ) ¹¹⁵Cd–^115mIn, ¹³⁰Ba(n,γ) ¹³¹Ba, and ¹⁵²Sm(n,γ) ¹⁵³Sm. These determinations were carried out under favorable experiment conditions: the irradiations were performed in a highly thermalized neutron flux, the irradiated target samples were counted at a far distance from HPGe detector with an efficiency carefully calibrated, and the k ₀-values were calculated against an internal comparator. When compared to the new values from this work, the 2003 recommended ^110mAg k ₀-values are confirmed. The other confirmed recommended k ₀-value is that of ⁷⁵Se 400.7 keV line. However, for the other ⁷⁵Se γ-lines, the new k ₀-values are 4–10 % higher. It is assumed that an inaccurate efficiency calibration was used when the recommended k ₀-values were measured. For the other three nuclides, the new k ₀-values are higher by 4 % for the ¹¹⁵Cd–^115mIn γ-lines, lower by 6–8 % for the ¹³¹Ba γ-lines, and lower by 8.8 % for the ¹⁵³Sm 103.2 keV γ-line.     

Gamow-Teller strength in the exotic odd-odd nuclei 138La and 180Ta and its relevance for neutrino nucleosynthesis

The Gamow-Teller strength distributions below the particle threshold in 138La and 180Ta, deduced from high-resolution measurements of the (3He,t) reaction at 0 degrees, allow us to evaluate the role of charged-current reactions for the production of these extremely rare nuclides in neutrino-nucleosynthesis models. The analysis suggests that essentially all 138La in the Universe can be made that way. Neutrino nucleosynthesis also contributes significantly to the abundance of 180Ta but the magnitude depends on the unknown branching ratio for population of the long-lived isomer.     

Anionic polymerization of butadiene: A MNDO study of the potential energy surface of the propagation reaction in polar and non-polar media

The anionic polymerization of butadiene, to both the 1,2- and 1,4-addition products, is an important industrial process. It is known that the reaction can be steered to either the 1,2- or 1,4-product by the addition, or absence, of a complexing solvent such as ether. The goals of the current study were to map the MNDO Potential Energy Surfaces (PES) of the propagation reactions both in the presence and absence of dimethyl ether to gain insight into the factors influencing the reaction's selectivity. Single point ab initio calculations at the DZP level were run on all reactants, products and transition states as a cross check on the MNDO results.