| 1. |
- Desjardins, Kewin, et al.
(author)
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Characterization of a back-illuminated CMOS camera for soft x-ray coherent scattering
- 2019
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In: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
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Conference paper (peer-reviewed)abstract
- A commercial scientific camera has been adapted and characterized at the SOLEIL Synchrotron with the aim to improve the acquisition capabilities on the soft X-ray coherent scattering experimental station at SEXTANTS beamline. This device is equipped by the last generation of back side illuminated scientific CMOS (BSI-sCMOS) of 2048 by 2048 pixels of 11 μm2 able to acquire low noise images with a frame rate up to 48 Hz. The camera's performance measurements have been done and shows a good level of readout noise, a large full-well capacity, a medium dark current and a good homogeneity, respectively, 1.6 e- rms (in High Gain mode), 80 000 e- (in Low Gain mode),<5 e-/pixel/s and ∼ 1%. The quantum efficiency (QE) measurement has been performed at the soft x-ray branch of the METROLOGIE beamline and gives a relatively good agreement with the expected theoretical values. Finally, the demonstration of the camera's efficiency and of the gain in useful time measurement related to the high frame rate have been performed with a series of Airy patterns images compared with an image recorded using the standard BSI-CDD already in operation at the SEXTANTS beamline.
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| 2. |
- Griesmayer, E., et al.
(author)
-
Applications of single-crystal CVD diamond XBPM detectors with nanometre x-ray beams
- 2019
-
In: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
-
Conference paper (peer-reviewed)abstract
- Measurements with a Diamond XBPM were carried out at the MAX IV Laboratory, Lund, Sweden, at the NanoMAX beam line. This was the first investigation of a Diamond XBPM detector with nanometre beams. The effect of diffusion, as well as the position resolution at the smallest available beam sizes were studied.
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| 3. |
- Marcouille, O., et al.
(author)
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Production of high energy photons with in vacuum wigglers : From SOLEIL wiggler to MAXIV wiggler
- 2019
-
In: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
-
Conference paper (peer-reviewed)abstract
- Small gap wigglers become more and more attractive to produce high photon fluxes in the hard X-ray photon range. They use magnet blocks of high magnetization which resists much better to heating (baking, synchrotron radiation) than in the past, produce high magnetic field with numerous periods and are very compact. They also are a very good alternative to superconducting technology which requires special infrastructure, heavy maintenance and is not running cost free. SOLEIL, operating presently at 2.75 GeV has designed and built an in-vacuum wiggler of 38 periods of 50 mm producing 2.1 T at a minimum gap of 5.5 mm to delivered photon beam between 20 keV and 50 keV. Already in operation, further improvements are presently in progress to push photons towards higher energy, in particular thanks to the operation at lower gap (4.5 mm). MAX IV and SOLEIL, in the frame of collaboration, ave built an upgraded version of the existing SOLEIL wiggler with the target to extend the spectral range at high energy (above 50 keV) but also at low energy (4 keV) with the same insertion device. The design of the existing magnetic system has been modified to reach 2.4 T at a minimum gap of 4.2 mm and includes taper operation to avoid undulator structure in the radiated spectrum at low energy.
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| 4. |
- Nemsak, Slavomir, et al.
(author)
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Element- and momentum-resolved electronic structure of the dilute magnetic semiconductor manganese doped gallium arsenide
- 2018
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- The dilute magnetic semiconductors have promise in spin-based electronics applications due to their potential for ferromagnetic order at room temperature, and various unique switching and spin-dependent conductivity properties. However, the precise mechanism by which the transition-metal doping produces ferromagnetism has been controversial. Here we have studied a dilute magnetic semiconductor (5% manganese-doped gallium arsenide) with Bragg-reflection standing-wave hard X-ray angle-resolved photoemission spectroscopy, and resolved its electronic structure into element-and momentum-resolved components. The measured valence band intensities have been projected into element-resolved components using analogous energy scans of Ga 3d, Mn 2p, and As 3d core levels, with results in excellent agreement with element-projected Bloch spectral functions and clarification of the electronic structure of this prototypical material. This technique should be broadly applicable to other multi-element materials.
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| 5. |
- Plivelic, Tomás S., et al.
(author)
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X-ray tracing, design and construction of an optimized optics scheme for CoSAXS, the small angle x-ray scattering beamline at MAX IV laboratory
- 2019
-
In: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
-
Conference paper (peer-reviewed)abstract
- A novel optical design for a flexible SAXS beamline at a modern synchrotron has been implemented for the CoSAXS beamline at the 3GeV ring at the MAX TV Laboratory. The performance of the beamline has been simulated through combined ray tracing and wave propagation with the code xrt taking into account the low emittance and highly coherent beam of MAX TV and the short inter-optics distances of the beamline. The total photon flux is estimated to be 1012-1013 ph/s with the coherent flux portion up to 10 % at 7.1 keV. The inhomogeneities in the X-ray beam arising from use of real (non-idealised) mirror surfaces are also modelled using the measured slope profiles of the mirrors. Strategies to mitigate these inhomogeneities are discussed. The optical components for CoSAXS have been constructed and beamline commissioning will start in 2019.
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| 6. |
- Abercrombie, Daniel, et al.
(author)
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Dark Matter benchmark models for early LHC Run-2 Searches : Report of the ATLAS/CMS Dark Matter Forum
- 2020
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In: Physics of the Dark Universe. - : Elsevier BV. - 2212-6864. ; 27
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Journal article (peer-reviewed)abstract
- This document is the final report of the ATLAS-CMS Dark Matter Forum, a forum organized by the ATLAS and CMS collaborations with the participation of experts on theories of Dark Matter, to select a minimal basis set of dark matter simplified models that should support the design of the early LHC Run-2 searches. A prioritized, compact set of benchmark models is proposed, accompanied by studies of the parameter space of these models and a repository of generator implementations. This report also addresses how to apply the Effective Field Theory formalism for collider searches and present the results of such interpretations.
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| 7. |
- Jain, Animesh, et al.
(author)
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Concise Loads and Stores : The Case for an Asymmetric Compute-Memory Architecture for Approximation
- 2016
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In: 2016 49Th Annual IEEE/ACM International Symposium On Microarchitecture (MICRO). - 9781509035083
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Conference paper (peer-reviewed)abstract
- Cache capacity and memory bandwidth play critical roles in application performance, particularly for data-intensive applications from domains that include machine learning, numerical analysis, and data mining. Many of these applications are also tolerant to imprecise inputs and have loose constraints on the quality of output, making them ideal candidates for approximate computing. This paper introduces a novel approximate computing technique that decouples the format of data in the memory hierarchy from the format of data in the compute subsystem to significantly reduce the cost of storing and moving bits throughout the memory hierarchy and improve application performance. This asymmetric compute-memory extension to conventional architectures, ACME, adds two new instruction classes to the ISA - load-concise and store-concise - along with three small functional units to the micro-architecture to support these instructions. ACME does not affect exact execution of applications and comes into play only when concise memory operations are used. Through detailed experimentation we find that ACME is very effective at trading result accuracy for improved application performance. Our results show that ACME achieves a 1.3x speedup ( up to 1.8x) while maintaining 99% accuracy, or a 1.1x speedup while maintaining 99.999% accuracy. Moreover, our approach incurs negligible area and power overheads, adding just 0.005% area and 0.1% power to a conventional modern architecture.
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