Primary slits are made of two blocks of copper and are water-cooled in order to evacuate heating from the high energy white beam. The alignment of the two holes drilled in the middle of the blocks allow to define position and size of the white beam. Both blocks are motorised and could be moved independantly vertically (PSU and PSD) and horizontally (PSB and PSF).



 In the other hand, it is possible to move both blocks at the same time by defining vertical/horizontal gap and offset: