Radiation hardness of low-mass readout cables for the CBM experiment

For the fixed-target heavy-ion experiment CBM at FAIR, a low-mass silicon tracking detector system is being developed that can track at high rates the hundreds of charged particles that will be created when an intense beam of heavy nuclei interacts with the target [1]. The detector is based on silicon microstrip detector technology. Fast self-triggering front-end electronics will be located at the periphery of the tracking system. The distance between the detectors and the electronics will be bridged with thin long aluminium cables structured into microstrip lines and insulated with polyimide. In the CBM environment, the exposure to ionizing radiation is estimated to about 100-200 kGy in several years of operation. For reliable operation, radiation-induced changes of the bulk and/or surface conductivity of the dielectric material have to be excluded.