Dr. Tanmoy Chattopadhyay

The next generation of large X-ray astronomical missions are planned to have an order-of-magnitude larger collecting areas combined with exquisite mirror quality, enabling exploration of the faint and high redshift X-ray universe. An essential component of these missions is the development of focal plane instrumentation with fast readout and excellent noise performance, on the order of single electrons, crucial especially for the soft X-ray performance. At Stanford University (SU), in collaboration with MIT Lincoln Laboratory (MIT-LL), MIT Kavli Institute (MKI), we have made substantial improvements in developing next generation X-ray CCDs, and associated readout electronics to support these detectors. For the AXIS probe mission (currently in the phase A study), we recently characterized a prototype CCD at 5 Megapixel/s (50 times faster than Chandra CCDs) with excellent noise performance. While these X-ray CCDs exceed the targeted speed and noise performance of AXIS, to meet the strict requirements of the future great observatory missions (e.g. the Lynx observatory), we are, in parallel, working on a novel Single electron Sensitive readout (SiSeRO) detector which can provide significantly greater responsivity and better noise performance. The first generation SiSeRO devices already achieve a charge to current conversion gain of >800 pA per electron, an equivalent noise charge (ENC) of 3.5 electrons root mean square (RMS), and a full width half maximum (FWHM) of <130 eV at 5.9 keV at a readout speed of 625 Kpixel/s. Importantly, utilizing the benefit that the charge signal remains unaffected by the readout process in these devices, we have also been able to implement Repetitive Non-Destructive Readout (RNDR) on our prototype devices, achieving significantly improved ENC performance. In this talk, I will discuss the working and characterization test results for these new fast, low noise X-ray CCDs and the novel SiSeRO devices.