Performance studies on the ohmic side of silicon microstrip sensors

High precision collider experiments at high energy accelerators and B-factories need accurate position resolution while preserving a low material budget for precise particle tracking. Thin double-sided silicon detectors (DSSDs) fulfill both requirements, if a careful sensor design is applied to maintain a high charge collection efficiency. In this continuation of a previous study we investigate the p-stop and the p-spray blocking methods for strip isolation on the n-side (ohmic side) of DSSDs with n-type bulk. We compare three different p-stop patterns: the common p-stop pattern, the atoll p-stop pattern and a combination of these patterns, and for every pattern four different geometric layouts are considered. Moreover we investigate the effect of the strip isolation on sensors with one intermediate strip. Sensors featuring these p-stop patterns and the p-spray blocking method were tested in a 120 GeV/c hadron beam at the SPS at CERN, γ-irradiated to 100 kGy at SCK-CEN (Mol, Belgium), and immediately afterwards tested again at CERN in the same setup as before. The results of these tests are used to optimize the design of DSSDs for the Belle II experiment at KEK (Tsukuba, Japan).