A high resolution tracker for (p,2p) reactions

Models of the r-process predict a strong influence of fission barrier heights on the distribution of r-process nuclei, manly through termination of the r-process and simultaneously by a recycling of the fission products, refueling the r-process with neutron rich, medium mass nuclei. The (p,2p)-reaction in inverse kinematics allows for the study of fission barrier heights for even the most exotic, experimentally available nuclei. For this purpose a missing mass spectroscopy of the reaction has to be performed. A silicon tracker system has been developed using highly segmented, thin silicon detectors with an APV25 based low noise readout. Tests of the system have been performed at the HIMAC facility in Japan, using a stable ¹⁶O beam at energies of E=290 MeV/u. Even at a readout speed of up to 100 kiloevents per second the experimental resolution of a vertex reconstruction is in excellent agreement with expectations from Geant4 simulations.