The particle tracking silicon microscope PTSM

A novel position- and energy-sensitive particle detector for radiobiological application is described. The aim is to support research in radiation response of biological systems, for example in the induction of mutations in C elegans, where precise knowledge of location and intensity of the radiation is crucial to understand radiation sensitivity of individual cells. The "Particle Silicon Tracking Microscope" (PTSM) consists of a silicon strip detector in direct contact with radiobiological samples (e.g., C elegans), such that the location and intensity of particle radiation can be controlled at the 10 μm scale. The readout is performed with low-noise readout electronics, which allows the determination of the particle\´s position from the hit strip address and its energy from the specific energy loss. In our implementation, the energy loss is measured through the time-over-threshold (TOT). The noise rate at acceptable thresholds is so low that the single particles can be detected with 100% efficiency. The performance of the front-end ASIC is described, and the results of initial environmental tests are reported. These include placing biological samples and saline solutions in direct contact with the silicon detectors.