Development of small pixel CZT detectors for future hard x-ray missions

Abstract

The NuSTAR (Nuclear Spectroscopic Telescope Array) mission launched in 2012, and it has successfully deployed the first orbiting telescopes to focus light in the high-energy X-ray range (3 -79 keV), providing a wealth of new information about the sources of high-energy X-rays. Follow-up missions such as the proposed HEX-P, BEST, and FORCE could perform a deeper black hole census providing a more refined measurement of black hole spins, allowing for greater knowledge about supermassive black holes. These missions are motivated by recent breakthroughs in hard X-ray mirror technologies where mirrors made of monolithic silicon segments and mirrors made directly or through replication of shells demonstrate the feasibility of making hard X-ray mirrors with angular resolutions of 5-10 arc seconds Half Power Diameter (HPD) compared to NuSTAR's 1 arc minute HPD. Such a high angular resolution requires matched detectors (higher pixel density) to fully benefit from the achievable improved spatial resolution. In the above framework, the development of the HEXID ASIC, embedding is a novel pixelated front-end suitable for reading out a finely segmented CZT sensor, is presented. The required large dynamic range (from 2 keV to 180 keV) and low input noise (ENC < 20 e − ) together with a small pixel size (150 µm) pose several design challenges in chip implementation. The chosen architecture of the front-end circuit and in-pixel processing blocks, together with the readout architecture of the registered signals and other adopted design solutions, driven by the quoted requirements, will be reviewed.

Integration of EDWARD readout architecture in full-field fluorescence imaging detector

“…There are 8 bits of data, one SYNC line and one STROBE line that form the internal SPB that reaches each pixel. One of these configuration settings related to the EDWARD readout interface is, for example, that a set pixel may start requesting to be read out regardless of the AFE (Analog Front-End) [6] state. Exemplary waveforms, carrying out commands on the I2C's SCL and SDA lines used to change configuration are shown in figure 2.…”