Speaker
Description
High energy physics (HEP) experiments require high-performance detectors to advance the energy, luminosity, and cosmology frontiers. Photomultiplier tubes (PMTs) have been extensively used to detect scintillation light. In recent years, silicon photomultipliers (SiPMs), an array of single photon avalanche diodes (SPADs), have become preferable as a solid-state alternative to PMTs due to their invulnerability to magnetic fields, compactness, low operating voltage, robustness, and lower cost. Furthermore, SiPMs implemented in a standard CMOS process, as opposed to a dedicated optical process, allow the optical sensor to be coupled on the same chip with the readout electronics. This results in a compact, low-cost, and low-bias voltage SiPM detector. However, SiPMs tend to rapidly degrade in high irradiation environments, making them unsuitable for some collider experiments, particularly given the trend towards higher luminosities and therefore higher irradiation levels. One of the major challenges of SiPM in such high-radiation environments is their noise performance. In addition, CMOS detectors have been developed for precision position measurements in HEP due to their compactness and spatial granularity. In recent years, developments have focused on sub-100 ps photon timing and direct particle detection.
To address the demands for timing precision and improved noise performance, the proposed project plans to develop an ultra-fast, low-cost, compact, scalable, and low-noise SiPM detector with integrated readout electronics. This idea involves integrating innovative perimeter field gates into SPADs within commercial CMOS processes to create perimeter-gated SPADs. Preliminary work has shown that the field modulating gate reduces the noise (dark count) of regular SPADs and SPAD-based SiPM detectors. To improve the timing resolution, we will design new front-end readout circuits at the pixel level and high-resolution time-to-digital converters (TDCs) at the system level. Detector performance will be optimized by pursuing a “chiplet” approach in which the SiPM devices and matched readout circuits are fabricated on separate dies using different, carefully selected fabrication processes and then integrated within the same package.
As a result of this research, we expect to create a new class of SiPM detectors that provides an order-of-magnitude improvement in key performance metrics, namely timing resolution and noise. In summary, the proposed novel scalable SiPM detectors will provide noise and timing resolutions far beyond what is currently available, allowing them to be used not only in HEP experiments that will be exposed to high radiation levels, but also in other applications such as long-term space missions.
