A cryo scanning transmission X-ray microscope, the cryo-STXM, has been designed and commissioned at the Canadian Light Source synchrotron. The instrument is designed to operate from 100 -4000 eV (λ = 12.4 -0.31 nm). Users can insert a previously frozen sample, through a load lock, and rotate it ±70° in the beam to collect tomographic data sets. The sample can be maintained for extended periods at 92 K primarily to suppress radiation damage, and a pressure on the order of 10 -9 Torr to suppress sample contamination. The achieved spatial resolution (30 nm) and spectral resolution (0.1 eV) are similar to other current soft X-ray STXMs, as demonstrated by measurements on known samples and test patterns. The data acquisition efficiency is significantly more favorable for both imaging and tomography. 2D images, 3D tomograms and 4D chemical maps of automotive hydrogen fuel cell thin sections are presented Introduction:Scanning transmission X-ray microscopy (STXM) is an established imaging technique for investigating the structure and composition of matter at the micro-to nanometer length scale.Briefly, in STXM an X-ray beam is focused down to a small spot onto a sample using optics such as a zone plate (ZP) lens or Kirkpatrick-Baez (KB) mirrors [1-3]. Two dimensional images are compiled from a series of line scans, performed by scanning the sample downstream of the optic(s), or by scanning the optic(s) upstream of the sample. Modern soft X-ray STXMs, such as the ambient-STXM at the Canadian Light Source (CLS, Saskatoon, Canada) spectromicroscopy (SM) beamline 10ID-1 [4], acquire images of sub-micrometer thick specimens with a bright field spatial resolution that is close to diffraction limited [5]: 30 nm half pitch is now considered routine at most facilities. When a STXM is combined with a soft X-ray beamline at a synchrotron, spectromicroscopy is enabled [2]. The focused beam can be held at one spatial location while the photon energy is scanned to perform X-ray absorption near edge spectroscopy (XANES) on a small volume [2]. More often, a series of monochromatic images over a photon energy range of interest is collected, and each pixel in the resulting "image stack" contains a XANES spectrum [6]. Image stacks can be converted into quantitative chemical maps using thickness normalized reference spectra [2]. Soft X-ray STXMs have found applications in diverse fields such as human health [7], agriculture [8], environmental studies [9], nanofabrication [10], and advanced materials [11].The overall form and function of current ZP based STXMs can be traced back to instruments built in the 1980s at the National Synchrotron Light Source (NSLS, Brookhaven National Laboratory, USA) [12,13]. A concise timeline of instrumentation developments from around the

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The Canadian Light Source (CLS) is a third-generation synchrotron located in Saskatoon, Canada. A superconducting radio frequency (SRF) cavity contained in a 4.43 K liquid helium I cryostat is used at the CLS to replenish energy loss in the electron beam. A dynamic simulation of this cryostat has been generated to examine pressure and level fluctuations due to variations in heat loading or other system parameters. This simulator has led to some interesting observations in system behavior, which have been shown to occur in the actual system as well. For example, mass rates of vaporization appear to drop as heat loading increases under certain conditions. Also, the relationship between pressure and SRF tuning characteristics is examined, and the abilities and limitations of the simulator are presented.