Our goniometer used is a classical one with step scanning motors both on θ and 2θ movements. The theoretical radius is 250 mm but it can be changed easily.
Two kinds of PSD have been used, the older one of a resistive type with a carbon coated quartz fiber and, for this year, a capacitive one with a gold-plated molybdenum wire anode, which is more reliable, with a very good pulse height analyser. It is connected to a 48K calculator (IN 90) with a floppy disk unit. A special interface has been made which is able to drive separately the 2θ and θ movements of the goniometer, using the output signals of the calculator. After the different settings of the goniometer and the initialization of the positions in 9 and 26, every movement can be ordered either by a very simple software from the keyboard or inside a more complex program.