Percival: An International Collaboration to Develop a MAPS-based Soft X-ray Imager

Abstract

Over the last decade, synchrotron radiation sources have seen a significant increase in brilliance, and the advent of free electron lasers has made entire new research fields accessible to investigations with X-rays. These advances in light source capabilities have resulted not only in a host of scientific advances and discoveries, but also in a need for a new generation of X-ray imaging detectors that can match the sources' capabilities in terms of frame rate and image dynamic range while recording image information with fine granularity over a large - preferably uninterrupted - (multi)megapixel area with single-photon sensitivity. Developing such next-generation imagers is both costly and time-consuming, and the requirements at many photon science facilities are similar enough to invite a collaborative effort. The Percival ("Pixellated Energy Resolving CMOS Imager, Versatile And Large") imager is being developed by a collaboration of DESY, Rutherford Appleton Laboratory (RAL), Elettra, and Diamond Light Source (DLS) to answer this need for the soft X-ray regim

Characterisation of a PERCIVAL monolithic active pixel prototype using synchrotron radiation

“…Images of these Airy patterns were measured with the old chip in the TwinMic beamline at Elettra Light source, as explained in [2] and [8]. A clear difference between the response from the different pixel types was visible.…”

Technology Needs for Modular Pixel Detectors

“…PERCIVAL [60][61][62][63][64], a large-area CMOS sensor for low-energy x-rays, has a seven-row readout architecture. PERCIVAL [60][61][62][63][64], a large-area CMOS sensor for low-energy x-rays, has a seven-row readout architecture.…”

Accurate determination of segmented X-ray detector geometry

“…Indexed after geometry refinement Gd:Lysozyme [22] (4N5R) 391,000 42% (164,000) 56% (218,000) Cathepsin B [24] (4HWY) 358,000 56% (201,000) 59% (210,000) DgkA [25] 180,000 60% (109,000) 78% (140,500) Rhodopsin-Arrestin [26] (4ZWJ) 11,000 20% (2,200) 80% (8,800) For data from two published data sets, Gd:Lysozyme [22] (Dataset 1, Ref. [27]) and Cathepsin B [24], the indexing rate improved noticeably after geometry refinement.…”

“…The first step in geometry calibration is to verify the starting detector geometry by forming a "virtual" powder diffraction pattern by summing all measured diffraction patterns 8 and, if necessary, altering the panel positions such that concentric powder diffraction rings line up with one other. This check enables coarse errors in detector geometry to be corrected.…”

“…Each pulse can measure a different crystal, and diffraction patterns can be measured at the pulse repetition rate, which so far has been up to 120 Hz. Detectors developed for such applications typically consist of several small detector modules tiled together to cover a larger area, for example the CSPAD detector [3,4], pnCCD [5], MPCCD [6], AGIPD [7] and Percival [8] detectors. Other segmented X-ray detector systems are either planned or under development, including detectors for synchrotron applications.…”