Radiation Hard Tight Pitch GaInP SPAD Arrays for High Energy Physics

High sensitivity optical photodetectors are critical components of many high energy physics experiments, where scintillators are used to convert particle energy and direction) into optical signals. Photomultiplier tubes PMTs) had previously been the gold standard for detecting these optical signals, but their susceptibility to magnetic fields, large size, low spatial resolution, and high operating voltages often exclude them from consideration. Recently, silicon single photon avalanche diode SPAD) arrays also known as silicon photomultipliers SiPMs) have been developed as a solid-state alternative to the PMT. Unfortunately, SiPMs degrade rapidly in high irradiation environments, making them unsuitable for some collider experiments, particularly given the trend toward higher luminosity and therefore higher irradiation levels. The proposed SBIR project will develop wide band gap compound semiconductor SPAD arrays to overcome the limitations of SiPM devices. Statement of the problem or situation that is being addressed. Currently available photodetectors are inadequate for next generation high energy physics experiments which require a unique combination of ultra-high optical sensitivity, low magnetic field sensitivity and superior radiation hardness. GaInP SPAD arrays have the potential to provide equivalent or better performance than SiPMs, while achieving orders of magnitude better radiation tolerance, providing a superior option for high energy physics experiments at high luminosity. LightSpin will characterize the performance of a new generation of GaInP Photomultiplier Chips, which have been designed to demonstrate their full potential for radiation hard applications. These devices will range in size from single SPAD elements to 4 mm 4 mm arrays, with pixel pitches ranging from 5 m to 50 m. In particular, the degradation of these devices with exposure to 67 MeV protons, 12 MeV electrons, and neutrons ~1 MeV energies), with doses up to 2 1013 cm-2 1 MeV neutron equivalent) will be used, and the resulting degradation in performance primarily dark current, dark count rate, signal-to-noise ratio) will be evaluated. A substantial fraction of $0.5B annual photomultiplier tube market can be directly addressed and emerging markets are anticipated. High sensitivity photodetectors are required for many scientific instruments, biomedical instruments, positron emission tomography PET), and remote sensing applications. Building a radiation hard photodetector not only provides access to a niche market collider experiments and space borne applications), but also provides a firm foundation for later entry into this larger ultrasensitive photodetector market.