Characterization of 128x128 MM-PAD-2.1 ASIC: A Fast Framing Hard X-Ray Detector with High Dynamic Range

TL;DR

This paper presents a detailed characterization of the MM-PAD-2.1 ASIC, a high-speed, high-dynamic-range x-ray detector capable of continuous imaging at up to 10 kHz, suitable for various x-ray energies.

Contribution

The paper introduces the MM-PAD-2.1 ASIC with dynamic charge removal, enabling deadtime-less, high-rate x-ray detection across a wide energy range.

Findings

Achieves >10^7 x-rays/pixel/frame dynamic range

Maintains low read noise at high flux levels

Operates continuously at up to 10 kHz frame rate

Abstract

We characterize a new x-ray Mixed-Mode Pixel Array Detector (MM-PAD-2.1) Application Specific Integrated Circuit (ASIC). Using an integrating pixel front-end with dynamic charge removal architecture, the MM-PAD-2.1 ASIC extends the maximum measurable x-ray signal (in 20 keV photon units) to > 10$^{7}$ x-rays/pixel/frame while maintaining a low read noise across the full dynamic range, all while imaging continuously at a frame rate of up to 10 kHz. The in-pixel dynamic charge removal mechanism prevents saturation of the input amplifier and proceeds in parallel with signal integration to achieve deadtime-less measurements with incident x-ray rates of > 10$^{10}$ x-rays/pixel/s. The ASIC format consists of 128$\times$128 square pixels each 150 $\mu$m on a side and is designed to be 3-side buttable so large arrays can be effectively tiled. Here we use both laboratory x-ray sources and the Cornell High Energy Synchrotron Source (CHESS) to characterize two single ASIC prototype detectors for both low (single x-ray) and high incident flux detection. In the first detector the ASIC was solder bump-bonded to a 500 $\mu$m thick Si sensor for efficient detection of x-rays below ~20 keV, whereas the second detector used a 750 $\mu$m thick CdTe sensor for x-rays above $\sim$ 20 keV.