Time-of-arrival detection for time-resolved scanning transmission X-ray microscopy imaging.

Simone Finizio,Sina Mayr,Jörg Raabe

doi:10.1107/s1600577520007262

Abstract

A setup for time-resolved scanning transmission X-ray microscopy imaging is presented, which allows for an increase in the temporal resolution without the requirement of operating the synchrotron light source with low-α optics through the measurement of the time-of-arrival of the X-ray photons. Measurements of two filling patterns in hybrid mode of the Swiss Light Source are presented as a first proof-of-principle and benchmark for the performances of this new setup. From these measurements, a temporal resolution on the order of 20-30 ps could be determined.

Highlights

A setup for time-resolved scanning transmission X-ray microscopy imaging is presented, which allows for an increase in the temporal resolution without the requirement of operating the synchrotron light source with low- optics through the measurement of the time-of-arrival of the X-ray photons
The use of an avalanche photodiode (APD) as a photon detector is suited for time-resolved imaging, as diodes with bandwidths above the X-ray pulse repetition rate are commercially available
The current setup employed for the acquisition of timeresolved scanning transmission X-ray microscopy (TRSTXM) images at the PolLux beamline of the Swiss Light Source (SLS) (Raabe et al, 2008), schematically shown in Fig. 1 and described in more detail in the work by Puzic et al (2010) and Finizio et al (2018), is based on a field-programmable gate array (FPGA) system, which consists of a 2 GSa sÀ1 ADC combined with a discriminator for determining whether the APD has detected a photon, followed by a demultiplexer (DEMUX) that sorts the detected photons as counts in a given counter channel dependent on the bunch where the X-ray photon was generated