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Overview of the experiment

The SAXS camera is a general purpose, modular instrument. Different sample environments, for soft or hard condensed matter, including in-situ triggering in time-resolved experiments, are possible. The camera length can be changed between ~270mm and 2200mm covering with photons from 5 to 20keV a q range from ~10-3 to 1 Å-1. It shares with the 7 circle diffractometer the optics (monochromator, mirrors and slits) and is constituted of modular elements set on a marble down stream the diffractometer. The horizontal beam is at 400mm over the marble and at 127.5mm from the guide rail.

Description of the camera and sample environment

  • On the 7 circle diffractometer are located the selection slits s4, the incident beam monitor, the filters and the rapid CCD shutter. Antiscattering independant slits ("s0") are positioned at the front side of the marble support of the camera.
    1. Standardly controlled by SAXSINT : completely under vacuum. An Y-Z positioning of samples is done by stepping motors (sensitivity 0.001mm, horizontal range 100mm; vertical 75mm; centered on the beam). Home made sample holders can be fixed on this translation stage (thickness in downstream direction <5mm, in upstream up to 80mm, for holes in square of 63mm for screws M4).

      One can stick samples on standard plates with 20 holes of diameter 8mm : their spacing is 20mm. The rows are labelled from A to D with Zsample= -30, -10, +10, +30 and the columns labelled from 1 to 5 (Xsample=-40, -20 , 0, +20, +40mm).

    2. Standardly controlled SAXSEXT in air between upstream and downstream vacuum tubes (mica or kapton windows).  An Y-Z positioning of 12 samples is done by stepping motors (sensitivity 0.001mm, two rows of 6 holes with horizontal range 250mm and separated vertically by ** mm).

    3. Particular home-made sample environment (discuss with a local contact); a DC alimentation (MIDEC 80V&9amp;7.5A ou 40V&15A) driven by an Eurotherm PID can be borrowed for furnace heating. For aligning a furnace a rotation rsamp is added to the Y-Z translations ; controlled by SAXSHT
    4. Standardly controlled by GISAXS: completely under vacuum. An Y-Z positioning of samples is done by stepping motors (sensitivity 0.001mm), horizontal range 20mm; vertical 5mm; centered on the beam, followed by a rotation of axis Y (0.001 degree per step) and by a manual Z translation in order that the rotation axis coincides with the sample surface.
  • Rear monitoring, from a retractable Kapton film moved up/down by a VPAP button, in vue of a scintillator (ISOLATED from the ELECTRICAL GROUND of its support); possibility of filter or pin holes frame insertion (attached on sample chamber)
  • Rear monitoring using a rapid retractable kapton fram, driven by air pressure: SPEC command "kapton on/off"
  • Vacuum tubes (250, 500 and 1000mm long) of diameter 100mm centered.
  • Beamstop chamber
    • X-Z translations (path of 0.001mm range +-12.5mm)
    • "O" frames (100 mm) for 2d detectors ( disk beamstops of  0.7 to 3mm diameter, or home made beam stop, as in the photo a beam  stop made of two wires

    • 100mm circular window
  • Detector supports for linear detector or for CCD detector: X translation (50mm); Z translation (100mm).

Vacuum inside the camera

From the optics down to the kapton window in front of the detector , the vacuum path may be shared in three independent parts, the optics one, including selection slits s4, front monitor, filters and rapid CCD shutter, a second one extending  to the sample and a third one from the sample to the detector; these last two sections may be one only in case of an evacuated sample holder.

  • pumping from primary pump

    1. close air leak
    2. close vacuum valve
    3. start pump
    4. open SLOWLY the valve (control by the manometer and reach vacuum in 1 minute at least)
    5. open FULLY the valve and LEAVE IT open
    6. check eventual leaks
  • breaking vacuum
    1. close the valve
    2. stop pump
    3. open SLOWLY the air leak (control by the manometer)

updated by jp simon