The ePix10k 2-megapixel hard X-ray detector at LCLS.

Tim Brandt Van Driel,Maciej Kwaitowski,Kaz Nakahara,Philip Hart,Christopher Kenney,Mark Mckelvey,Rebecca Armenta,Stephen Boo,Angelo Dragone,Marco Oriunno,Takahiro Sato,Silke Nelson,Dionisio Doering,Gunther Haller,Leo Manger,Gabriel Blaj,Matt Weaver,Sébastien Boutet

doi:10.1107/s1600577520004257

Tim Brandt Van Driel, Maciej Kwaitowski + Show 16 more

Open Access

https://doi.org/10.1107/s1600577520004257

Copy DOI

Abstract

The ePix10ka2M (ePix10k) is a new large area detector specifically developed for X-ray free-electron laser (XFEL) applications. The hybrid pixel detector was developed at SLAC to provide a hard X-ray area detector with a high dynamic range, running at the 120 Hz repetition rate of the Linac Coherent Light Source (LCLS). The ePix10k consists of 16 modules, each with 352 × 384 pixels of 100 µm × 100 µm distributed on four ASICs, resulting in a 2.16 megapixel detector, with a 16.5 cm × 16.5 cm active area and ∼80% coverage. The high dynamic range is achieved with three distinct gain settings (low, medium, high) as well as two auto-ranging modes (high-to-low and medium-to-low). Here the three fixed gain modes are evaluated. The resulting dynamic range (from single photon counting to 10000 photons pixel-1 pulse-1 at 8 keV) makes it suitable for a large number of different XFEL experiments. The ePix10k replaces the large CSPAD in operation since 2011. The dimensions of the two detectors are similar, making the upgrade from CSPAD to ePix10k straightforward for most setups, with the ePix10k improving on experimental performance. The SLAC-developed ePix cameras all utilize a similar platform, are tailored to target different experimental conditions and are designed to provide an upgrade path for future high-repetition-rate XFELs. Here the first measurements on this new ePix10k detector are presented and the performance under typical XFEL conditions evaluated during an LCLS X-ray diffuse scattering experiment measuring the 9.5 keV X-ray photons scattered from a thin liquid jet.

Highlights

X-ray free-electron lasers (XFELs) have opened the possibility to investigate ultrafast processes using extremely bright femtosecond X-ray pulses
Most XFEL experiments require detectors that measure the X-ray intensities on a shot-to-shot basis. This defines the target requirements for a detector running at the repetition rate of the XFEL (120 Hz for Linac Coherent Light Source (LCLS)) and the dynamic range to contain the maximum number of photons pixelÀ1 pulseÀ1 in a given experiment as well as allowing detection of experiment specific weak features
An example of such an experiment is the study of chemical dynamics through X-ray diffuse scattering (XDS) of molecules in solution, where a liquid jet is excited with an optical laser pulse and probed at different

Summary

Introduction

X-ray free-electron lasers (XFELs) have opened the possibility to investigate ultrafast processes using extremely bright femtosecond X-ray pulses. Most XFEL experiments require detectors that measure the X-ray intensities on a shot-to-shot basis This defines the target requirements for a detector running at the repetition rate of the XFEL (120 Hz for LCLS) and the dynamic range to contain the maximum number of photons pixelÀ1 pulseÀ1 in a given experiment as well as allowing detection of experiment specific weak features. An example of such an experiment is the study of chemical dynamics through X-ray diffuse scattering (XDS) of molecules in solution, where a liquid jet is excited with an optical laser pulse and probed at different. This makes this type of experiment an excellent test of new detector performance

Camera design

Ghost images

Linearity

Findings

Conclusion