Omni-directional, ultra small angle X-ray scattering imaging provides a method to measure the orientation of micro-structures without having to resolve them. In this letter, we use single-photon localization with the Timepix3 chip to demonstrate the first laboratory-based implementation of single-shot, omni-directional X-ray scattering imaging with the beam-tracking technique. The setup allows for a fast and accurate retrieval of the scattering signal using a simple absorption mask. We suggest that our new approach may enable faster laboratory-based tensor tomography and could be used for energy resolved X-ray scattering imaging, useful in mitigate scattering signal artifacts caused by polychromatic illumination. 2020The measurement of ultra small angle X-ray scattering from sub-resolution sample structures is within X-ray imaging commonly referred to as the dark-field contrast [1,2]. The dark-field contrast has potential within both non-destructive testing [3,4] and medical [5] applications as it

 Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Timepix3 (256  256 pixels with a pitch of 55 mm) is a hybrid-pixel-detector readout chip that implements a data-driven architecture and is capable of simultaneous time-of-arrival (ToA) and energy (ToT: time-over-threshold) measurements. The ToA information allows the unambiguous identification of pixel clusters belonging to the same X-ray interaction, which allows for full oneby-one detection of photons. The weighted mean of the pixel clusters can be used to measure the subpixel position of an X-ray interaction. An experiment was performed at the European Synchrotron Radiation Facility in Grenoble, France, using a 5 mm  5 mm pencil beam to scan a CdTe-ADVAPIX-Timepix3 pixel (55 mm  55 mm) at 8  8 matrix positions with a step size of 5 mm. The head-on scan was carried out at four monochromatic energies: 24, 35, 70 and 120 keV. The subpixel position of every single photon in the beam was constructed using the weighted average of the charge spread of single interactions. Then the subpixel position of the total beam was found by calculating the mean position of all photons. This was carried out for all points in the 8  8 matrix of beam positions within a single pixel. The optimum conditions for the subpixel measurements are presented with regards to the cluster sizes and beam subpixel position, and the improvement of this technique is evaluated (using the charge sharing of each individual photon to achieve subpixel resolution) versus alternative techniques which compare the intensity ratio between pixels. The best result is achieved at 120 keV, where a beam step of 4.4 mm AE 0.86 mm was measured.research papers

The simultaneous retrieval of X-ray attenuation, phase, and scattering using multimodal imaging techniques is finding increased use in a range of applications, from medicine to materials science. Most techniques rely on the mechanical movement of an optical element (e.g. a grating or a mask) to obtain the multi-modal images. While single-shot approaches exist, they typically employ detector pixels smaller than the grating period, often with low detection efficiency, and are limited in resolution unless either the sample or the optical element is displaced in various positions and multiple frames are collected. In this paper, we replace mechanical motion with the MÖNCH detector's capability to reach sub-pixel resolutions by interpolating between neighbouring pixels collecting the charge generated by a single X-ray event. This enabled us to obtain the pilot demonstration of a laboratory-based high-resolution, single-shot multimodal imaging technique capable of simultaneously retrieving attenuation and directional differential phase and scatter images, without any mechanical movement. We show that our proof-of-concept setup enables a single-shot resolution of 19.5 μm, and that the resulting images provide sufficient information to produce a reliable sample thickness map. Furthermore, we demonstrate that the setup is capable of producing single-shot directional scattering images, while leaving open the option to further increase the resolution by using sample dithering.

The crystal structure of the mineral boleite contains clusters of 24 S = 1/2 Cu 2+ ions that have the shape of a truncated cube formed of eight trimers connected by edges. Susceptibility measurements and exact diagonalization calculations suggest that there are strong antiferromagnetic intratrimer interactions, such that effective S = 1/2 degrees of freedom emerge on the trimers below T 100 K. Weaker intertrimer interactions lead to the formation of a singlet ground state for these effective spins at T 5 K. The clusters in boleite offer a situation similar to single molecule magnetism, accessible to both experiment and numerics, in which the interplay of quantum spins, geometric frustration, spin entanglement, and mesoscopic system size can be studied.