RESUMO
The vibrational stability of a horizontally deflecting double-crystal monochromator (HDCM) is investigated. Inherently a HDCM will preserve the vertical beam stability better than a `normal' vertical double-crystal monochromator as the vibrations of a HDCM will almost exclusively affect the horizontal stability. Here both the relative pitch vibration between the first and second crystal and the absolute pitch vibration of the second crystal are measured. All reported measurements are obtained under active cooling by means of flowing liquid nitrogen (LN2). It is found that it is favorable to circulate the LN2 at high pressures and low flow rates (up to 5.9â bar and down to 3â lâ min(-1) is tested) to attain low vibrations. An absolute pitch stability of the second crystal of 18â nrad RMS, 2-2500â Hz, and a relative pitch stability between the two crystals of 25â nrad RMS, 1-2500â Hz, is obtained under cryocooling conditions that allow for 1516â W to be adsorbed by the LN2 before it vaporizes.
RESUMO
A high precision five rotation-axes polarimeter using transmission multilayers as polarizers and reflection multilayers as analyzers has been designed and manufactured. To cover the extreme ultraviolet regime, Mo/Si, Cr/C, Sc/Cr, and W/B4C multilayers for transmission and reflection have also been designed and produced. The polarimeter mechanics is supported on a hexapod to simplify the alignment relative to photon beam. The instrument is designed so that it can be easily transferred between different beamlines.