The slits system on the D2am SAXS camera

Incoming beam slits

After the 3 slits system described in the Overview of the beamline Optic, the slit (s4) system manufactured by Riso has a 40*40mm aperture defined by four independent lips. This slit can be moved lip by lip : slit up (su4), slit down (sd4), slit front (sf4) and slit back (sb4), or with pseudo-motors gap (hg4, vg4) and offset (ho4,vo4). s4 is under secondary vacuum. It is located on the goniometer about 2.50m upstream of the SAXS table. It is used to define the beam size in the horizontal (hg4) and vertical (vg4) directions. It is worth at this stage to check that the beam is not screened by : the CCD beam shutter (diameter 6mm), the windows separating the different evacuated sections, the sample-holder, the beam-stop.

Antiscattering slits.

Just before the sample are the antiscattering slits s0, with independant lips (su0, sd0, sf0, sb0) made of polished Ta rolls as edges; they can overlap without jam by about 5mm: mind after optics alignement and before slits settings that you can screen the beam completely by moving the lips to the positive hard limits.

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