Fast GPU-based absolute intensity determination for energy-dispersive X-ray Laue diffraction

Abstract

A: This paper presents a novel method for fast determination of absolute intensities in the sites of Laue spots generated by a tetragonal hen egg-white lysozyme crystal after exposure to white synchrotron radiation during an energy-dispersive X-ray Laue diffraction experiment. The Laue spots are taken by means of an energy-dispersive X-ray 2D pnCCD detector. Current pnCCD detectors have a spatial resolution of 384 × 384 pixels of size 75 × 75 µm 2 each and operate at a maximum of 400 Hz. Future devices are going to have higher spatial resolution and frame rates.The proposed method runs on a computer equipped with multiple Graphics Processing Units (GPUs) which provide fast and parallel processing capabilities. Accordingly, our GPU-based algorithm exploits these capabilities to further analyse the Laue spots of the sample. The main contribution of the paper is therefore an alternative algorithm for determining absolute intensities of Laue spots which are themselves computed from a sequence of pnCCD frames. Moreover, a new method for integrating spectral peak intensities and improved background correction, a different way of calculating mean count rate of the background signal and also a new method for n-dimensional Poisson fitting are presented.We present a comparison of the quality of results from the GPU-based algorithm with the quality of results from a prior (base) algorithm running on CPU. This comparison shows that our algorithm is able to produce results with at least the same quality as the base algorithm. Furthermore, the GPU-based algorithm is able to speed up one of the most time-consuming parts of the base algorithm, which is n-dimensional Poisson fitting, by a factor of more than 3. Also, the entire procedure of extracting Laue spots' positions, energies and absolute intensities from a raw dataset of pnCCD frames is accelerated by a factor of more than 3.

EDLD-Tool: A real-time GPU-based tool to stream and analyze energy-dispersive Laue diffraction of BIG Data sets collected by a pnCCD

“…Valid singlepixel events are those collected only in one pixel, while valid multi-pixel events spread over two, three and four pixels. Pile-up events result from the record of more than one photon in one pixel following Poisson statistics, generating -as approximation -a forbidden amplitude distribution [8]. Owing to the fact that each recorded event is originated by one photon, the valid single-pixel events are considered, while the valid multi-pixel events are then reconstructed to individual photon hits by calculating the center-of-mass coordinates for each event [24].…”

“…Thus, high-performance computing (HPC) is a "must" to realize online data treatment. Parallel processor technology and multi-core Graphic Processing Units (GPUs) have already been used for many applications in the field of detector technology, including real-time processing of pnCCD images [7][8][9]. Examples taken from singlecrystalline materials have demonstrated the reliability of this approach for in-situ visualization and data analysis [10][11][12].…”

Full elastic strain tensor determination at the phase scale in a powder metallurgy nickel-based superalloy using X-ray Laue microdiffraction

“…In the past decade, the versatility of the Laue technique has been greatly improved in synchrotrons by Kirkpatrick-Baez (KB) mirrors (Kirkpatrick & Baez, 1948), which reshape the incident beam to submicrometre sizes, by fast sample positioning and detector acquisitions that enable strain mapping, and by the development of analysis software that can process large volumes of data (Chung & Ice, 1999;Tamura et al, 2002;Micha & Robach, 2010;Alghabi et al, 2014Alghabi et al, , 2016Tamura, 2014). The technique is now commonly used at the Advanced Light Source, the Advanced Photon Source and the European Synchrotron Radiation Facility (ESRF) to probe materials properties and provides useful insights at a scale that can also be investigated by dislocation dynamics and finite element calculations (Korsunsky et al, 2012).…”