Large-area pixellated photon counting X-ray imaging system

A large-area pixellated photon counting imaging system, primarily for synchrotron radiation research, is under development. An area of 300 mm×300 mm will be covered by tiling many modules. A module will comprise a 64×448 array of 150 μm×150 μm silicon pixels covering an area of 9.6 nm×67.2 mm. This will be flip chip bonded to 7 ALADIN readout chips, that each contain a 64×64 array of 144 mm×150 μm pixels. Each readout pixel comprises a pre-amplifier, shaper, discriminator, 15-bit counter and 5-bit register that enables threshold adjust, pixel masking and calibrate control. Each pixel is designed to operate at ∼1 MHz providing a count rate capability of ∼10 ⁹ cm ^-2 s ^-1. The system will operate in the energy range from 4 to 25 keV and at a frame rate of up to 1 kHz. The current status of the project is reported, along with the detector guard structure chosen to minimise the dead region around the active volume of the silicon detector.