Development Of High Resolution Imaging Detectors For X Ray Astronomy PDF Download

The next generation of soft X-ray telescopes plan to push the boundaries of X-ray astronomy by featuring large increases in effective area. The most difficult observations, such as will be required to fully explore the low-luminosity and high-redshift X-ray Universe, will need to couple this high throughput with very fine angular resolution -- as is currently being studied for the Lynx mission concept. At the focal planes of instruments equipped to carry out this work will be arrays of small pixels (to oversample the telescope point spread function) that are capable of low-noise, rapid readout (to avoid pile-up of X-ray photons). While traditional X-ray charge-coupled devices (CCDs) have now been the workhorse imaging sensors in X-ray astronomy for ~ 25 years, these requirements -- specifically low-noise, rapid readout -- are outside their capabilities. Active pixel sensors (APSs) are a natural alternative due to their highly parallel readout. They also offer several other advantages, including less susceptibility to radiation damage, low power consumption, and nondestructive and windowed readout. Several APS technologies are currently under development; this work focuses on hybrid complementary metal-oxide-semiconductor (CMOS) detectors, with additional smaller-scale discussion of depleted p-channel field-effect transistors (DePFETs). Through detailed characterization of these technologies, this dissertation aims to demonstrate the advancement of hybrid CMOS detectors (HCDs) and DePFETs towards future flagship X-ray space telescopes like Lynx. After briefly reviewing the history and current state of X-ray astronomy, the dissertation continues with a discussion of the physics of soft X-ray detection, along with details on the operation of CCDs, HCDs, and DePFETs. Following this is a description of the design, testing, and full characterization results of prototype small-pixel HCDs -- which have been specifically developed to meet the needs of a Lynx-class observatory. Results include measurements of the read noise, dark current, pixel well capacity, pixel crosstalk, charge diffusion, pixel-to-pixel gain variation, and spectral resolution. The subsequent section features initial testing results from prototype DePFETs sensors, along with a discussion of their possible development path. Finally, the dissertation closes with an exploration of the exciting novel X-ray astronomy that will be possible with future instruments that may utilize these technologies.