Status of silicon edgeless detector developments for close-to-beam experiments

Abstract

The development of silicon edgeless strip detectors was stimulated by the needs of the TOTEM experiment at CERN to detect protons scattered at very small angles (i.e. close-to-beam applications). The setup of the TOTEM Roman Pots demands a dead region at the detector-sensitive diced side (or cut) that should be less than 50 μm. During the design phase, two approaches were proposed: detectors with current terminating structure (the CTS approach) and 3D active edge detectors. The planar detectors with a CTS were developed by a collaboration of TOTEM and Russian institutions. The key idea of the CTS approach is the ability to control the current distribution at the sensitive cut by incorporating special rings along the detector edge. In the study, the approach using edgeless detectors with a CTS is overviewed in its physical background and its potential for future applications in close-to-beam experiments, including the requirements for the radiation hardness of the detector. The current experimental results on edgeless p-on-n detectors obtained in the framework of the TOTEM experiment and the INTAS-CERN project are also presented. This approach, using an edgeless p-on-n detector with a CTS design, was successfully realized in the final size TOTEM detectors and allowed achieving a total non-sensitive width of about 50 μm.