The Bi(d,γ)Po reaction

The yield of the ²⁰⁹Bi(d, γ)^211g.s.Po and ^211mPo (T_1/2 = 25.2s) reaction was measured for deuteron energies E_d = 8–11.5 MeV. The reaction was identified by the -activities of the Po isotope. At E_d = 10.43 MeV, the (d, γ) cross section for the population of the ground state of ²¹¹Po is σ_g.s. = 16 ± 3 μb, the ratio relative to the cross section for the metastable state is σ_g.s./σ_m = 25.4 ± 0.9. These values and the yield curves were compared with calculations using a simple model for the population of the two states. In the excitation region E* = 15–19 MeV, the branching ratio of γ- to particle emission is nearly constant and has a value of about 0.4 × 10⁻⁴.     

Das Spektrum der energiereichen Protonen aus der Reaktion O16(γ,p)N15

Oxygen gas was irradiated with 34·5 MeV bremsstrahlung. The spectrum of protons between 6 MeV and 22 MeV was measured with a Na I(Tl) scintillation spectrometer. The energy resolution was equivalent to that obtainable with nuclear photoplates, but the number of protons registered was much higher. The differential cross section for (γ, p) reactions that leave the residual nucleus in the ground state was found to be 0·13 mbarn/steradian at 30 MeV gamma ray energy and at 90° with respect to the direction of the incident beam.     

Field and pressure response of Yb compounds close to a quantum critical point

YbCu_5−x Al _x provides the possibility to tune ground state properties by a change of the valence due to the Cu/Al substitution, by pressure as well as by the application of a magnetic field. Near to the critical concentration x _cr≈1.5 non-Fermi-liquid properties (NFL) are obvious, obeying hyperscaling. If magnetic order sets in for x>1.5, the application of moderate magnetic fields quenches order and again NFL features become evident. Hyperscaling in this case indicates strongly interacting spin fluctuations.     

Investigation of two resonances in the18O(p,n)18F reaction

Excitation functions for the¹⁸O(p,n)¹⁸F reaction were measured at bombarding energiesE _p=4.6 to 6.6 MeV. In and near two resonances of the yield curves atE _p=5.622 and 6.061 MeV, angular distributions were measured with neutron time-of-flight techniques. The strong neutron decay to theT=1 state in¹⁸F and the similarity of the¹⁸O(p,n) and¹⁸O(n,n) yield curves give good evidence that the structures in the¹⁸O(p,n) yield curve arise from the formation ofT=3/2 states in¹⁹F. A two-level-analysis does not give satisfactory fits to the strongly asymmetric angular distributions.     

Analyzing power for elasticn-d scattering at 13 MeV

The analyzing power for elasticn-d scattering was measured atE _n=13 MeV. The result is in good agreement with experimental data atE _n =12 MeV andE _n =14.1 MeV. At backward angles the data are well above the predictions of a rigorous Faddeev calculation using the Paris potential.