| 1. |
- Walker, Anthony P, et al.
(författare)
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Horizon 2020 EuPRAXIA design study
- 2017
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 874:1
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Tidskriftsartikel (refereegranskat)abstract
- The Horizon 2020 Project EuPRAXIA ("European Plasma Research Accelerator with eXcellence In Applications") is preparing a conceptual design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics (HEP) detector tests, and other applications such as compact X-ray sources for medical imaging or material processing. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. EuPRAXIA aims to be included on the ESFRI roadmap in 2020.
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| 2. |
- Behm, K. T., et al.
(författare)
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A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV
- 2018
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 89:11
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 Author(s). We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.
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| 3. |
- Cole, J. M., et al.
(författare)
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Experimental Evidence of Radiation Reaction in the Collision of a High-Intensity Laser Pulse with a Laser-Wakefield Accelerated Electron Beam
- 2018
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Ingår i: Physical Review X. - 2160-3308. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of energetic particles in strong electromagnetic fields can be heavily influenced by the energy loss arising from the emission of radiation during acceleration, known as radiation reaction. When interacting with a high-energy electron beam, today's lasers are sufficiently intense to explore the transition between the classical and quantum radiation reaction regimes. We present evidence of radiation reaction in the collision of an ultrarelativistic electron beam generated by laser-wakefield acceleration (μ 500 MeV) with an intense laser pulse (a0 > 10). We measure an energy loss in the postcollision electron spectrum that is correlated with the detected signal of hard photons (γ rays), consistent with a quantum description of radiation reaction. The generated γ rays have the highest energies yet reported from an all-optical inverse Compton scattering scheme, with critical energy > 30 MeV.
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| 4. |
- Warwick, J., et al.
(författare)
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Experimental Observation of a Current-Driven Instability in a Neutral Electron-Positron Beam
- 2017
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 119:18
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (amp;gt;= 1 T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of epsilon(B) approximate to 10(-3) is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.
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| 5. |
- Attieh, Randa, et al.
(författare)
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Validation of the Canadian French version of the fear of COVID-19 scale in the general population of Quebec
- 2022
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Ingår i: Brain and Behavior. - : John Wiley & Sons. - 2162-3279 .- 2162-3279. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe purpose of this study was to develop a Canadian French translation of the fear of COVID-19 scale (FCV-19S) and assess its psychometric characteristics.MethodsA forward and backtranslation process was conducted for the Canadian French version of the FCV-19S. The guidance of the ISPOR task force for translation and cultural adaptation was followed and cognitive debriefing interviews were conducted with six citizens. The final proofread Canadian French FCV-19S was then administered to a large sample of citizens from the province of Quebec in Canada through an online survey. A quota sampling was conducted in 2020. Respondents from the survey also completed the Clinical Outcomes in Routine Evaluation (CORE)-6D and the Sense of Coherence (SOC-3) questionnaires. Several psychometric tests were performed to investigate the reliability (internal consistency) and validity of the Canadian French FCV-19S, including construct validity, concurrent validity, and Rasch analysis.ResultsThe translation process was conducted without any major difficulties. The cognitive debriefing interviews led to no change in the reconciled translation. The survey collected answers from 3428 citizens. Results indicated that the factor structure of the Canadian French FCV-19S is a unidimensional factor fitting well with the data. The scale showed adequate reliability (Cronbach's alpha of .903) and concurrent validity, as indicated by significantly negative correlation with CORE-6D (r = -.410) and SOC-3 (r = -.233). The Canadian French FCV-19S properties tested using Rasch analysis was also very satisfactory.ConclusionsThe results of the present study indicated that the Canadian French version of FCV-19S is a unidimensional tool with robust psychometric properties in the adult's population of all ages residing in the province of Quebec, Canada.
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| 6. |
- Sarri, Gianluca, et al.
(författare)
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Laser-driven generation of collimated ultra-relativistic positron beams
- 2013
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Ingår i: Plasma Physics and Controlled Fusion. - London : Institute of Physics (IOP). - 0741-3335 .- 1361-6587. ; 55:12
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Tidskriftsartikel (refereegranskat)abstract
- We report on recent experimental results concerning the generation of collimated (divergence of the order of a few mrad) ultra-relativistic positron beams using a fully optical system. The positron beams are generated exploiting a quantum-electrodynamic cascade initiated by the propagation of a laser-accelerated, ultra-relativistic electron beam through high-Z solid targets. As long as the target thickness is comparable to or smaller than the radiation length of the material, the divergence of the escaping positron beam is of the order of the inverse of its Lorentz factor. For thicker solid targets the divergence is seen to gradually increase, due to the increased number of fundamental steps in the cascade, but it is still kept of the order of few tens of mrad, depending on the spectral components in the beam. This high degree of collimation will be fundamental for further injection into plasma-wakefield afterburners.
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