PSD12: The 12th International Conference on Position Sensitive Detectors

Spectroscopic X-ray Imaging at MHz Frame Rates – The HEXITECMHz ASIC

15 Sept 2021, 17:45

15m

Teaching and Learning Building (University of Birmingham)

talk X-ray and Gamma Ray Detectors X-ray and Gamma Ray Detectors 2

Speaker

Lawrence Jones (UKRI STFC)

Description

The HEXITEC${}_{MHz}$ ASIC has been developed for the HEXITEC${}_{MHz}$ Detector System, to deliver spectroscopic x-ray imaging at frame rates up to 1MHz for future high-flux-rate applications. Optimised for sensing electron signals from detector materials such as CdTe, CZT, GaAs, Ge and p-type silicon detectors, the design has an array of 80x80 pixels on a pitch of 250$\mu$m, with each pixel capable of measuring single x-ray photons up to energies of 200keV, with a resolution of 1keV FWHM.

Further improvements in the spatial and spectroscopic resolution are possible due to the pixel’s ability to simultaneously sense positive signals up to 20keV induced by internal weighting potential effects from electron signals on neighbouring pixels.

A count rate limit of around 10${}^6$ photons s${}^{-1}$ mm${}^{-2}$ is achieved by converting the signals from all pixels every 1$\mu$s using 12-bit time-to-digital converters – an improvement of two orders of magnitude over previous HEXITEC ASICs. To save power, each converter is shared between groups of eight pixels.

Each 76.8kbit data frame is Aurora 64b/66b encoded and serialised over 20 lanes of differential CML, all operating in parallel at 4.1Gbps.

In this paper, we present details of the design, and possibly preliminary test results from the ASIC.

Presentation materials

HEXITEC_MHZ.pdf