| 1. |
- 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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| 2. |
- 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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| 3. |
- Baird, C. D., et al.
(författare)
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Realising single-shot measurements of quantum radiation reaction in high-intensity lasers
- 2019
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 21:5
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Tidskriftsartikel (refereegranskat)abstract
- Modern laser technology is now sufficiently advanced that collisions between high-intensity laser pulses and laser-wakefield-accelerated (LWFA) electron beams can reach the strong-field regime, so that it is possible to measure the transition between the classical and quantum regimes of light-matter interactions. However, the energy spectrum of LWFA electron beams can fluctuate significantly from shot to shot, making it difficult to clearly discern quantum effects in radiation reaction (RR), for example. Here we show how this can be accomplished in only a single laser shot. A millimetre-scale pre-collision drift allows the electron beam to expand to a size larger than the laser focal spot and develop a correlation between transverse position and angular divergence. In contrast to previous studies, this means that a measurement of the beam's energy-divergence spectrum automatically distinguishes components of the beam that hit or miss the laser focal spot and therefore do and do not experience RR.
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| 4. |
- Ridgers, C. P., et al.
(författare)
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Signatures of quantum effects on radiation reaction in laser-electron-beam collisions
- 2017
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Ingår i: Journal of Plasma Physics. - : Cambridge University Press (CUP). - 0022-3778 .- 1469-7807. ; 83:5
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Tidskriftsartikel (refereegranskat)abstract
- Two signatures of quantum effects on radiation reaction in the collision of a similar to GeV electron beam with a high intensity (>3 x 10(20) W cm(-2)) laser pulse have been considered. We show that the decrease in the average energy of the electron beam may be used to measure the Gaunt factor g for synchrotron emission. We derive an equation for the evolution of the variance in the energy of the electron beam in the quantum regime, i.e. quantum efficiency parameter eta (sic) 1. We show that the evolution of the variance may be used as a direct measure of the quantum stochasticity of the radiation reaction and determine the parameter regime where this is observable. For example, stochastic emission results in a 25 % increase in the standard deviation of the energy spectrum of a GeV electron beam, 1 fs after it collides with a laser pulse of intensity 10(21) W cm(-2). This effect should therefore be measurable using current high-intensity laser systems.
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