PICMIC-0: a 5 μm pitch hexagonal pixel sensor with an original tri-axis readout

We present in this paper a new sensor called PICMIC-0 that is intended to exploit the intrinsic spatial resolution of the MicroChannel Plate (MCP) detectors. Manufactured using 6-metal TowerJazz 180 nm wafer technology, the sensor features hexagonal charge collection pixels on the top metal layer with a pitch of 5 μm and covering an area of 7.4 × 6.4 mm2. The 2 million of the pixels of this sensor are not read out individually. Each pixel is connected to a straight-line in either 0°, 120° or -120° orientation, in which a current is produced in case of a hit. Each of these readout strip-lines is connected to a readout cell which receives this current, amplifies it using a current mirror and converts it into a digital signal by means of a current comparator. The data is collected from the digital outputs of the readout cells using a priority encoder readout scheme and transmitted in frames of 400 ns. This projective readout system reduces the number of channels to be read out from 2 million pixels to 2556 readout cells integrated within the pixel matrix. Using three projections reduces the ambiguity in case of multiple hits.