Abstract
The Short Pulse X-ray facility planned for the Advanced Photon Source (APS) upgrade will provide two sectors with photon beams having picosecond pulse duration. The Short Pulse Soft X-ray Spectroscopy (SPSXS) beamline will cover the 150-2000 eV energy range using an APS bending magnet. SPSXS is designed to take full advantage of this new timing capability in addition to providing circular polarized radiation. Since the correlation between time and electron momentum is in the vertical plane, the monochromator disperses in the horizontal plane. The beamline is designed to maximize flux and preserve the time resolution by minimizing the number of optical components. The optical design allows the pulse duration to be varied from 1.5 to 100 ps full width at half-maximum (FWHM) without affecting the energy resolution, and the resolution to be changed with minimal effect on the pulse duration. More than 10(9) photons s(-1) will reach the sample with a resolving power of 2000 and a pulse duration of ∼2 ps for photon energies between 150 and 1750 eV. The spot size expected at the sample position will vary with pulse duration and exit slit opening. At 900 eV and at a resolving power of 2000 the spot will be ∼10 µm × 10 µm with a pulse duration of 2.3 ps FWHM.
Highlights
The Short Pulse Soft X-ray Spectroscopy (SPSXS) beamline is one of the beamlines planned for the upgrade of the Advanced Photon Source (APS) at Argonne National Laboratory which will occur during 2013–2020
The short-pulse X-ray (SPX) facility will be equipped with high-power and high-repetition-rate femtosecond lasers, similar to those already existing at the Advanced Photon Source (March et al, 2011)
The flux at the sample position as a function of the photon energy was calculated when the time slit was set to a pulse length of 2.3 ps full width at halfmaximum (FWHM), taking into account the flux emitted by the bending magnet (Fig. 1), the reflectivity of the three mirrors assuming they are Au coated, the efficiency of the gratings assuming they are gold coated and that the low-energy grating (LEG), medium-energy grating (MEG) and high-energy grating (HEG) are blazed at 0.51, 0.56 and 0.68, respectively
Summary
The Short Pulse Soft X-ray Spectroscopy (SPSXS) beamline is one of the beamlines planned for the upgrade of the Advanced Photon Source (APS) at Argonne National Laboratory which will occur during 2013–2020. Two soft X-ray beamlines using the slicing technique proposed by Zholents & Zolotorev (1996) for obtaining pulses with sub-100 fs time resolution are operational, one at the BESSY II storage ring (Khan et al, 2006) and the other at the Advanced Light Source (Heimann et al, 2007). Both beamlines use radiation from an undulator. In the sections below we describe the electron and photon source, the optical design and the expected performance of the SPSXS beamline as well as ray tracings verifying the analytical calculations
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