2021/03/12 by Peter Walter, Andrei Kamalov, Walter, Peter +21 · 1 citation
Physics and Astronomy · Engineering · #Advanced X-ray Imaging Techniques #Particle Accelerators and Free-Electron Lasers #Laser-Matter Interactions and Applications
paper · pdf · doi:10.48550/arxiv.2103.07603
We report the design of an angular array of electron Time-of-Flight (eToF)\nspectrometers intended for non-invasive spectral, temporal, and polarization\ncharacterization of single shots of high-repetition rate, quasi-continuous,\nshort-wavelength Free-Electron Lasers (FELs) such as the LCLS-II at SLAC. This\narray also enables angle-resolved, high-resolution eToF spectroscopy to address\na variety of scientific questions of ultrafast and nonlinear light--matter\ninteraction at FELs. The presented device is specifically designed for the\nTime-resolved atomic, Molecular and Optical science end station (TMO) at\nLCLS-II. In its final version, it can comprise of up to 20 eToF spectrometers\naligned to collect electrons from the interaction point defined by the\nintersection of the incoming FEL radiation and a gaseous target. There are 16\nsuch spectrometers forming a circular equiangular array in the plane normal to\nx-ray propagation and 4 spectrometers at 54.7^\∘ angle relative to the\nprinciple linear x-ray polarization axis. The spectrometers are capable of\nindependent and minimally chromatic electrostatic lensing and retardation in\norder to enable simultaneous angle-resolved photo-electron and Auger electron\nspectroscopy with high energy resolution. They are designed to ensure energy\nresolution of 0.25 eV across an energy window of up to 75 eV which can be\nindividually centered via the adjustable retardation to cover ranges of\nelectron kinetic energies relevant to soft x-ray methods, 0--2 keV. The full\nspectrometer array will enable non-invasive and online spectral-polarimetry\nmeasurements, polarization-sensitive attoclock spectroscopy for characterizing\nthe full time--energy structure of even SASE or seeded LCLS-II pulses, and also\nsupports emerging trends in molecular frame spectroscopy measurements.\n