Willem Cornelis Middelkoop

Radioactive decay of 103Ru

Synopsis The decay of 103Ru has been investigated with a scintillation spectrometer, a β-ray lens spectrometer, and by β-γ absorption coincidence measurements. With the scintillation spectrometer the X-ray and two strong γ-rays were found with the following energies and relative intensities: 20 keV (9.1%), 498 keV (100%) and 611 keV (7.8%). In addition three very weak γ-rays were observed at 53 keV (0.4%), 295 keV (0.4%) and 357 keV (0.25%). With the β-ray spectrometer the K conversion coefficient of the 611 keV γ-ray was found as (0.06 ± 0.02)%, which characterizes this transition as E1. Also the intensity of the weak β-component with an endpoint of 702 keV was measured as 2.9%. Absorption measurements of the β−-particles in coincidence with the 611 keV γ-ray show that there exits a third β-ray branch with an endpoint of 145 ± 35 keV, in addition to the known β-ray branches with endpoints of 217 and 702 keV. No coincidences were found between the 702 keV β-ray branch and the 53 keV γ-ray, showing that the half life of the 53 keV level is greater than 10 μsec. The 103Rh level scheme deduced from these measurements is in agreement with that given by Cork et al., except for the spin of the 611 keV level and of 103Ru. There are strong arguments that both are J = ½+. Also the levels found from Coulomb excitation by Heydenburg and Temmer at 295 keV (J = 3/2−) and 357 keV (J = 5/2−) have been confirmed from the 103Ru decay.

Target Stations and Beam Dumps for the CERN SPS

The design of the absorber blocks for internal and external dumping of the SPS proton beam is discussed. In addition, the external target stations for slow and fast extracted proton beams are described.