Design and first tests of the Gotthard-II readout ASIC for the European X-ray Free-Electron Laser

TL;DR

The paper presents the design, fabrication, and initial testing of the Gotthard-II ASIC, a high-performance X-ray detector readout chip for free-electron laser applications, demonstrating promising performance in initial experiments.

Contribution

It introduces a novel charge-integrating ASIC with high sensitivity, dynamic range, and speed tailored for X-ray free-electron laser diagnostics and experiments.

Findings

Achieved low noise and high linearity in the ASIC

Demonstrated successful X-ray absorption spectrum measurement

Validated performance in energy dispersive X-ray experiments

Abstract

Gotthard-II is a charge-integrating microstrip detector developed for experiments and diagnostics at free-electron lasers using hard X-rays of 5 keV - 20 keV. Thanks to its excellent single photon sensitivity, large dynamic range as well as high frame rate of 4.5 MHz in burst mode, its potential scientific applications include X-ray absorption/emission spectroscopy, hard X-ray high resolution single-shot spectrometry (HiREX), beam diagnostics, as well as veto signal generation for pixel detectors. The Gotthard-II ASIC has been designed and fabricated using UMC-110 nm technology. The final ASIC design and performance in terms of noise, linearity, dynamic range, coupling between channels and speed will be discussed in the paper. In addition, a first measurement of an X-ray absorption spectrum of a standard copper sample has been done. The performance of the Gotthard-II in an experiment using energy dispersive X-rays has been demonstrated.