Development of CMOS sensors for particle physics and applications

This proposal is focused on generic R&D for CMOS sensors and their applications. It is aligned with two recently approved STFC projects: SPIDER (Silicon Pixel Detectors R&D) and PNPAS project 'Fast CMOS sensors for Imaging Mass Spectroscopy (IMS)'. The latest generation of particle physics detectors have made increasing use of silicon sensors for vertexing, tracking, calorimetry and luminosity monitoring. This trend is likely to continue into the future, as can be seen from the current proposals for sLHC upgrades and the recent linear collider detector concept studies. For future vertex detectors, the demand is for a small pixel size with reduced power and material per layer. CMOS sensors are also used in many high end applications. The SPIDER project is focused on developing monolithic silicon pixel sensors which provide the required granularity for future high energy and high luminosity experiments and also addresses the major issues such as power consumption, connectivity and cost reduction for silicon pixel detectors. Because a monolithic silicon device integrates both the sensor and the front end (FE) electronics, it immediately decreases the material per measurement layer and simplifies assembly. The use of CMOS processes available from multiple vendors, compared with silicon detectors requiring high-resistivity wafers, provides a cost benefit and opens up the use of monolithic silicon pixel sensors not only for particle physics but also for multiple other applications. The IMS project will develop fast imaging sensors for use in a next-generation time-of-flight mass spectrometer (TOF-MS) with unique imaging capabilities. This technique provides the structural information about molecules in addition to the mass spectrum and has a promise to become a new standard in mass spectroscopy. The required CMOS sensor has a lot of synergy with the SPIDER sensors and will be designed by the same RAL team. Both SPIDER and IMS sensors will be based on the patented deep submicron CMOS process INMAPS and will have similarities in the underlying technology and functionality. Several CMOS sensors will be designed, manufactured and characterized during the duration of 3 years. One sensor type, Cherwell,will have low power consumption and no inactive area. A column will be divided into short 128 cell strixels shortening the readout time by a factor of 10 with other chip functionality distributed over the whole chip area. This approach could allow to minimize or indeed get rid of the dead area. TPAC, another sensor type in SPIDER, sacrificed about 10% of active area to implement an on-sensor memory. The IMS sensor will have a capability to store several time stamps per pixel similarly to TPAC but will have a rolling shutter architecture for the pixel readout. It is expected that the CASE student will take active part in the preparation of the sensor design, characterization of the new sensors, design of the readout electronics and data acquisition and its testing. Extensive ISE TCAD simulations of sensor performance will be required as well. All work will be done in close coordination between Oxford and RAL sensor design groups. In summary, the proposed research program will provide opportunities for the successful candidate to become a world expert in CMOS sensors and their readout and, in general, to acquire considerable expertise in semiconductors, readout electronics, particle detectors and their application to mass spectroscopy.