Speaker
Description
Resonant Inelastic X-ray Scattering (RIXS) is a powerful spectroscopic technique that can probe complex electronic-structural information. Due to the wealth of possible science cases (ranging from quantum-correlated materials to photochemistry and catalysis), RIXS spectrometers have become integral parts of the scientific landscape at most synchrotron facilities and X-ray Free Electron Lasers (XFELs). The capabilities of photon detectors employed in these spectrometers strongly influence the efficiency and resolution RIXS experiments can achieve. To enhance spectrometer performance, detector technologies that improve frame rate and active area are highly sought after.
The recent development of inverse Low-Gain Avalanche Diode (iLGAD) sensors optimized for soft X-rays has opened the possibility of employing hybrid pixel detectors for RIXS. These detectors offer substantial advantages in the areas where current systems are limited, i.e., frame rates more than three orders of magnitude higher than commercial CCD cameras and a customizable detector size.
We have developed a prototype detector for soft X-ray RIXS based on the JUNGFRAU readout electronics combined with iLGAD sensor technology. The total size of the device is $4\times4\,\text{cm}^2$, comprising four JUNGFRAU 1.0 readout chips bonded to a single iLGAD sensor. The sensor was fabricated by Fondazione Bruno Kessler (FBK, Trento Italy) and features a rectangular pixel design with $25\times225\,\text{µm}^2$ pixels and staggered bump bonds matching the ASIC array of 75 µm square pixels. This design enables high spatial resolution with interpolation in the energy dispersive direction of the RIXS spectrometer by utilizing the charge sharing between neighbouring pixels. First tests of this new JUNGFRAU system have been carried out at the Heisenberg-RIXS (hRIXS) spectrometer of the Spectroscopy and Coherent Scattering (SCS) instrument at European XFEL, and at SwissFEL Furka with soft X-ray photons from the Cu L-edge (~ 930 eV) and down to the O K-edge (~ 525 eV). These experiments demonstrate the capabilities of the JUNGFRAU-iLGAD system and serve to pinpoint routes for improvement, particularly, increasing the efficiency at grazing incidence angles.
