Evaluation of the X-ray SOI pixel detector with the on-chip ADC

TL;DR

This paper evaluates a new XRPIX X-ray detector with an integrated on-chip ADC, demonstrating high energy resolution and linearity suitable for satellite applications.

Contribution

The paper introduces and assesses a novel XRPIX device with an integrated on-chip ADC, enhancing compactness for satellite deployment.

Findings

Integral non-linearity of 6 LSB (36 eV)

Input noise of 5 e^{-} from ADC

Energy resolution of 294 eV at 5.9 keV

Abstract

XRPIX is the monolithic X-ray SOI (silicon-on-insulator) pixel detector, which has a time resolution better than 10 $\rm{\mu}$s as well as a high detection efficiency for X-rays above 10 keV. XRPIX is planned to be installed on future X-ray satellites. To mount on satellites, it is essential that the ADC (analog-to-digital converter) be implemented on the detector because such peripheral circuits must be as compact as possible to achieve a large imaging area in the limited space in satellites. Thus, we developed a new XRPIX device with the on-chip ADC, and evaluated its performances. As the results, the integral non-linearity was evaluated to be 6 LSB (least significant bit), equivalent to 36 eV. The differential non-linearity was less than 0.7 LSB, and input noise from the on-chip ADC was 5~$\rm{e^{-}}$. Also, we evaluated end-to-end performance including the sensor part as well as the on-chip ADC. As the results, energy resolution at 5.9 keV was 294 $\rm{\pm}$ 4 eV in full-width at half maximum for the best pixel.