The proton capture cross sections of the stable ruthenium isotopes 96, 98, 99, and 104 have been measured by means of the activation method in the proton energy range between 1.5 and 3 MeV. Thin layers of natural ruthenium were irradiated at the Karlsruhe 3.75 MV Van de Graaff accelerator with proton beams of 20–50 μA. The activity induced by $(p,\gamma )$ reactions was measured with a calibrated HPGe detector. In this way, six $(p,\gamma )$ cross sections for populating ground states and isomers in four different Rh isotopes could be determined simultaneously with systematic uncertainties of typically 4–5 %. The fact that experimental data are almost completely missing in the $A>\mathrm{}70\mathrm{}$ region illustrates the need of checking and complementing the statistical model calculations which are so far the only data used in $p$ process studies.

• Received 12 March 1998

DOI:https://doi.org/10.1103/PhysRevC.58.524