| 1. |
- Bakker, B.L.G., et al.
(författare)
-
Light-front quantum chromodynamics. A framework for the analysis of hadron physics
- 2014
-
Ingår i: Nuclear Physics B - Proceedings Supplements. - : Elsevier BV. - 0920-5632. ; 251-252, s. 165-174
-
Tidskriftsartikel (refereegranskat)abstract
- An outstanding goal of physics is to find solutions that describe hadrons in the theory of strong interactions, Quantum Chromodynamics (QCD). For this goal, the light-front Hamiltonian formulation of QCD (LFQCD) is a complementary approach to the well-established lattice gauge method. LFQCD offers access to the hadrons' nonperturbative quark and gluon amplitudes, which are directly testable in experiments at existing and future facilities. We present an overview of the promises and challenges of LFQCD in the context of unsolved issues in QCD that require broadened and accelerated investigation. We identify specific goals of this approach and address its quantifiable uncertainties. © 2014 Elsevier B.V.
|
|
| 2. |
- Behm, K. T., et al.
(författare)
-
A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV
- 2018
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 89:11
-
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.
|
|
| 3. |
- Cole, J. M., et al.
(författare)
-
Experimental Evidence of Radiation Reaction in the Collision of a High-Intensity Laser Pulse with a Laser-Wakefield Accelerated Electron Beam
- 2018
-
Ingår i: Physical Review X. - 2160-3308. ; 8:1
-
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.
|
|
| 4. |
- Dinu, V., et al.
(författare)
-
Photon polarization in light-by-light scattering: Finite size effects
- 2014
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 2470-0010 .- 2470-0029. ; 90:4
-
Tidskriftsartikel (refereegranskat)abstract
- We derive a simple expression for the photon helicity and polarization-flip probabilities in arbitrary background fields, in the low-energy regime. Taking the background to model a focused laser beam, we study the impact of pulse shape and collision geometry on the probabilities and on ellipticity signals of vacuum birefringence. We find that models which do not account for pulse duration can overestimate all signals in near head-on collisions by up to an order of magnitude. Taking pulse duration into account, the flip probability becomes relatively insensitive to both angular incidence and the fine details of the pulse structure.
|
|
| 5. |
- Dinu, Victor, et al.
(författare)
-
Quantum Radiation Reaction: From Interference to Incoherence
- 2016
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 116:4
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate quantum radiation reaction in laser-electron interactions across different energy and intensity regimes. Using a fully quantum approach which also accounts exactly for the effect of the strong laser pulse on the electron motion, we identify in particular a regime in which radiation reaction is dominated by quantum interference. We find signatures of quantum radiation reaction in the electron spectra which have no classical analogue and which cannot be captured by the incoherent approximations typically used in the high-intensity regime. These signatures are measurable with presently available laser and accelerator technology.
|
|
| 6. |
- Dinu, V., et al.
(författare)
-
Vacuum refractive indices and helicity flip in strong-field QED
- 2014
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 2470-0010 .- 2470-0029. ; 89:12
-
Tidskriftsartikel (refereegranskat)abstract
- Vacuum birefringence is governed by the amplitude for a photon to flip helicity or polarization state in an external field. Here, we calculate the flip and nonflip amplitudes in arbitrary plane wave backgrounds, along with the induced spacetime-dependent refractive indices of the vacuum. We compare the behavior of the amplitudes in the low energy and high energy regimes, and analyze the impact of pulse shape and energy. We also provide the first lightfront-QED derivation of the coefficients in the Heisenberg-Euler effective action.
|
|
| 7. |
- Gonoskov, Arkady, et al.
(författare)
-
Anomalous radiative trapping in laser fields of extreme intensity
- 2014
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 113, s. 014801-
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that charged particles in a suciently intense standing wave are compressed toward, and oscillate synchronously at, the antinodes of the electric eld. We call this unusualbehaviour `anomalous radiative trapping' (ART). We show using dipole pulses, which oer a pathto increased laser intensity, that ART opens up new possibilities for the generation of radiationand particle beams, both of which are high-energy, directed and collimated. ART also provides a mechanism for particle control in high-intensity quantum-electrodynamics experiments.
|
|
| 8. |
- Gonoskov, Arkady, 1984, et al.
(författare)
-
Extended particle-in-cell schemes for physics in ultrastrong laser fields : Review and developments
- 2015
-
Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 92:2
-
Tidskriftsartikel (refereegranskat)abstract
- We review common extensions of particle-in-cell (PIC) schemes which account for strong field phenomena in laser-plasma interactions. After describing the physical processes of interest and their numerical implementation, we provide solutions for several associated methodological and algorithmic problems. We propose a modified event generator that precisely models the entire spectrum of incoherent particle emission without any low-energy cutoff, and which imposes close to the weakest possible demands on the numerical time step. Based on this, we also develop an adaptive event generator that subdivides the time step for locally resolving QED events, allowing for efficient simulation of cascades. Further, we present a unified technical interface for including the processes of interest in different PIC implementations. Two PIC codes which support this interface, PICADOR and ELMIS, are also briefly reviewed.
|
|
| 9. |
- Gonoskov, Arkady, et al.
(författare)
-
Probing Nonperturbative QED with Optimally Focused Laser Pulses
- 2013
-
Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 111:6
-
Tidskriftsartikel (refereegranskat)abstract
- We study nonperturbative pair production in intense, focused laser fields called e-dipole pulses. We address the conditions required, such as the quality of the vacuum, for reaching high intensities without initiating beam-depleting cascades, the number of pairs which can be created, and experimental detection of the created pairs. We find that e-dipole pulses offer an optimal method of investigating nonperturbative QED.
|
|
| 10. |
- Gonoskov, Arkady, 1984, et al.
(författare)
-
Ultrabright GeV Photon Source via Controlled Electromagnetic Cascades in Laser-Dipole Waves
- 2017
-
Ingår i: Physical Review X. - 2160-3308. ; 7:4
-
Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic cascades have the potential to act as a high-energy photon source of unprecedented brightness. Such a source would offer new experimental possibilities in fundamental science, but in the cascade process radiation reaction and rapid electron-positron plasma production seemingly restrict the efficient production of photons to sub-GeV energies. Here, we show how to overcome these energetic restrictions and how to create a directed GeV photon source, with unique capabilities as compared to existing sources. Our new source concept is based on a controlled interplay between the cascade and anomalous radiative trapping. Using specially designed advanced numerical models supported with analytical estimates, we demonstrate that the concept becomes feasible at laser powers of around 7 PW, which is accessible at soon-to-be-available facilities. A higher peak power of 40 PW can provide 10(9) photons with GeV energies in a well-collimated 3-fs beam, achieving peak brilliance 9 x 10(24) ph s(-1) mrad(-2) mm(-2)/0.1%BW.
|
|
