Categories of exhibits
Variable alpha slit
Exhibit no. 979
The slits are used to impose geometrical constraints on the moving ions, and only those that can go through the opening proceed further into the analyzers, while the rest collide with the walls of the slits.
The exhibit is a variable alpha restrictor assembly from the ZAB-EQ sector mass spectrometer manufactured by VG Analytical LTD. in 1986. It comprises an aperture plate mounted on a UHV bellows linear motion drive. The aperture plate has four slits that can be used to restrict the angular divergence of the ion beam. This was used mainly for high-resolution accurate mass measurements, particularly in the FAB mode of operation. When the micrometer was fully retracted, the slit plate was fully removed from the beam.
