Software for the data analysis of the arrival-timing monitor at SACLA

Abstract

X-ray free-electron laser (XFEL) pulses from SPring-8 Ångstrom Compact free-electron LAser (SACLA) with a temporal duration of <10 fs have provided a variety of benefits in scientific research. In a previous study, an arrival-timing monitor was developed to improve the temporal resolution in pump-probe experiments at beamline 3 by rearranging data in the order of the arrival-timing jitter between the XFEL and the synchronized optical laser pulses. This paper presents Timing Monitor Analyzer (TMA), a software package by which users can conveniently obtain arrival-timing data in the analysis environment at SACLA. The package is composed of offline tools that pull stored data from cache storage, and online tools that pull data from a data-handling server in semi-real time during beam time. Users can select the most suitable tool for their purpose, and share the results through a network connection between the offline and online analysis environments.

Melting of magnetic order in NaOsO3 by femtosecond laser pulses

“…The temporal jitter between x-ray and optical laser pulses was measured shot-by-shot using a transmission grating based timing tool, which has an accuracy t T T = 10 fs (FWHM) [51]. The temporal fingerprint of each shot was then used to rebin all data into t bin = 50 fs time segments [52]. The effective time resolution of the experiment was estimated to be 5) fs (FWHM).…”

Characterization of soft X-ray FEL pulse duration with two-color photoelectron spectroscopy

“…The branched beam was focused onto a GaAs wafer to induce a transient change of the optical reflectivity, which was probed using synchronized nearinfrared (NIR) pulses and detected with a visible-light CCD camera (Owada et al, 2019). The arrival time differences were determined with a resolution of 15 AE 5 fs, which corresponds to a few pixels on the CCD image (Nakajima et al, 2018). The remaining FEL beam and the NIR laser beam (h = 1.57 eV) were introduced to a vacuum chamber in an almost collinear geometry and focused onto a gaseous He target.…”

Femtosecond Optical Laser System with Spatiotemporal Stabilization for Pump-Probe Experiments at SACLA

“…We have developed a relative arrival timing monitor between the XFEL and the optical laser pulses. The timing monitor, which is based on a spatial decoding method using a transient optical transmittance change of gallium arsenide (GaAs) irradiated by intense X-ray pulses, can sort data sets of pump-probe measurements in the order of the arrival time to correct the error due to the jitter in post-processing [23][24][25]35,36]. Figure 14 shows the optical setup of the timing monitor at EH1.…”

“…The operation of this laser system has been stabilized in terms of power and pointing by controlling conditions of temperature and air-flow in the optical path. Regarding the timing of the laser system, we had employed a synchronization system with direct detection of an optical pulse train, which has a jitter of ~0.3 ps [23][24][25]. Recently, a feedback system using a "balanced optical-microwave phase detector (BOMPD)" working at a C-band frequency was developed and enabled reduction of the jitter down to ~50 fs.…”