Charge Collection in Silicon Strip Detectors

1. A collimated MeV proton beam in the laboratory has proved useful and convenient to examine some details of charge collection in segmented silicon function detectors - "strip" detectors. Because fluoresced x-rays are not important to this measurement a further reduction in emergent beam size could be effected by finer, heavy metal collimaters, yielding beams down to ≈ 3-5 μm. Adequate beam then limited by beam line vibration, e.g. is easily attainable suggesting further studies in the range of expected beam diffusion sizes. 2. Simple surface barrier devices with a representative test pattern have been produced by contact lithography. 3. Negative pulses from adjacent electrodes have been observed and are attributed to charge injection. This effect should not be of great concern for minimum ionizing particles. 4. Diffusion of charge is at most ≈ 10 μm for representative device parameters and must be somewhat less for particles which fully traverse the active depth. The difference between linear and constant fields in the structure should be recognized. 5. Operation at full depletion obviates problems of material inhomogeneity. Therefore in large scale experiments it is hard to imagine not operating these detectors fully depleted. 6. The strip pitch for fine resolution of fully depleted detectors (σ<10μm) should be of the order of 2σ. Larger pitch would introduce nonlinearity in the position measurement and smaller pitch would not improve the centroid definition.