The Active Diamond Target
Layout of the active target: front-side a) and back-side b). Real picture of graphite electrodes c).
The target used by the PADME experiment is an active device able to provide beam intensity and impinging position with a sub-millimetric precision. It consist of a 100 μm thick (20×20 mm2) polycrystalline CVD diamond with orthogonal strip electrodes on the two sides. The strips, 1 mm wide, have been created with a graphitization technique by means of an excimer ArF laser at the L3 Laser Laboratory in Lecce. In this way no extra material has been added to the target itself. The target readout is performed by means of AMADEUS chips form IDEA that hold charge sensitive pre-amplifiers providing analog outputs.
The target, together with the front-end electronics, is mounted on a vacuum flange and its placement in front of the positron beam is controlled by a linear positioning system which employs a bellow.
The diamond target with its electronics during the mounting phase.