| 1. |
- Abramowicz, H., et al.
(författare)
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Conceptual design report for the LUXE experiment
- 2021
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Ingår i: European Physical Journal-Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 230:11, s. 2445-2560
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Tidskriftsartikel (refereegranskat)abstract
- This Conceptual Design Report describes LUXE (Laser Und XFEL Experiment), an experimental campaign that aims to combine the high-quality and high-energy electron beam of the European XFEL with a powerful laser to explore the uncharted terrain of quantum electrodynamics characterised by both high energy and high intensity. We will reach this hitherto inaccessible regime of quantum physics by analysing high-energy electron-photon and photon-photon interactions in the extreme environment provided by an intense laser focus. The physics background and its relevance are presented in the science case which in turn leads to, and justifies, the ensuing plan for all aspects of the experiment: Our choice of experimental parameters allows (i) field strengths to be probed where the coupling to charges becomes non-perturbative and (ii) a precision to be achieved that permits a detailed comparison of the measured data with calculations. In addition, the high photon flux predicted will enable a sensitive search for new physics beyond the Standard Model. The initial phase of the experiment will employ an existing 40 TW laser, whereas the second phase will utilise an upgraded laser power of 350 TW. All expectations regarding the performance of the experimental set-up as well as the expected physics results are based on detailed numerical simulations throughout.
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| 2. |
- Pirozhkov, A. S., et al.
(författare)
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Diagnostic of laser contrast using target reflectivity
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:24
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Tidskriftsartikel (refereegranskat)abstract
- Using three different laser systems, we demonstrate a convenient and simple plasma based diagnostic of the contrast of high-power short-pulse lasers. The technique is based on measuring the specular reflectivity from a solid target. The reflectivity remains high even at relativistic intensities above 10(19) W/cm(2) in the case of a high-contrast prepulse-free laser. On the contrary, the specular reflectivity drops with increasing intensities in the case of systems with insufficient contrast due to beam breakup and increased absorption caused by preplasma.
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| 3. |
- Turcu, I. C. E., et al.
(författare)
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HIGH FIELD PHYSICS AND QED EXPERIMENTS AT ELI-NP
- 2016
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Ingår i: Romanian Reports on Physics. - 1221-1451 .- 1841-8759. ; 68, s. S145-S231
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Tidskriftsartikel (refereegranskat)abstract
- ELI-NP facility will enable for the first time the use of two 10 PW laser beams for quantum electrodynamics (QED) experiments. The first beam will accelerate electrons to relativistic energies. The second beam will subject relativistic electrons to the strong electromagnetic field generating QED processes: intense gamma ray radiation and electron-positron pair formation. The laser beams will be focused to intensities above 10(21) Wcm(-2) and reaching 10(22)-10(23) Wcm(-2) for the first time. We propose to use this capability to investigate new physical phenomena at the interfaces of plasma, nuclear and particle physics at ELI-NP. This High Power Laser System Technical Design Report (HPLS-TDR2) presents the experimental area E6 at ELI-NP for investigating high field physics and quantum electrodynamics and the production of electron-positron-pairs and of energetic gamma-rays. The scientific community submitted 12 commissioning runs for E6 interaction chamber with two 10 PW laser beams and one proposal for the CETAL interaction chamber with 1 PW laser. The proposals are representative of the international high field physics community being written by 48 authors from 14 European and US organizations. The proposals are classified according to the science area investigated into: Radiation Reaction Physics: Classical and Quantum; Compton and Thomson Scattering Physics: Linear and Non Linear Regimes; QED in Vacuum; Atoms in Extreme Fields. Two pump-probe colliding 10 PW laser beams are proposed for the E6 interaction chamber. The focused pump laser beam accelerates the electrons to relativistic energies. The accelerated electron bunches interact with the very high electro-magnetic field of the focused probe laser beam. We propose two main types of experiments with: (a) gas targets in which the pump laser-beam is focused by a long focal length mirror and drives a wakefield in which the electron bunch is accelerated to multi-GeV energies and then exposed to the EM field of the probe laser which is tightly focused; (b) solid targets in which both the pump and probe laser beams are focused on the solid target, one accelerating the electrons in the solid and the other, delayed, providing the high electric field to which the relativistic electrons are subjected. We propose four main focusing configurations for the pump and probe laser beams, two for each type of target: counter-propagating 10 PW focused laser beams and the two 10 PW laser beams focused in the same direction. For solid targets we propose an additional configuration with plasma-mirror on the pump laser beam: the plasma mirror placed between the focusing mirror and target. It is proposed that the 10 PW laser beams will have polarization control and focus control by means of adaptive optics. Initially only one 10 PW may have polarization control and adaptive optics. In order to accommodate the two laser beams and diagnostics the proposed interaction chamber is quasi-octagonal with a diameter of 4.5 m. A large electron-spectrometer is proposed for multi-GeV electrons. Other diagnostics are requested for: gamma-rays, electrons and positrons, protons and ions, plasma characterization, transmitted and reflected laser beam. Targets will be provided by the ELI-NP Target Laboratory or purchased. The E6 experiments and diagnostics will benefit from the ELI-NP Electronics Laboratory, the Workshop and the Optics Laboratory. In order to ensure radiation-protection, a large beam-dump is planned for both multi-GeV electrons and multi-100 MeV protons.
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| 4. |
- Brenner, C. M., et al.
(författare)
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Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets
- 2011
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Ingår i: Laser and Particle Beams. - 0263-0346. ; 29:3, s. 345-351
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Tidskriftsartikel (refereegranskat)abstract
- The scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15-380 mJ at intensities of 10(16)-10(18) W/cm(2). The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.
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| 5. |
- 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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| 6. |
- 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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| 7. |
- Dromey, B, et al.
(författare)
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Picosecond metrology of laser-driven proton bursts.
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Tracking primary radiation-induced processes in matter requires ultrafast sources and high precision timing. While compact laser-driven ion accelerators are seeding the development of novel high instantaneous flux applications, combining the ultrashort ion and laser pulse durations with their inherent synchronicity to trace the real-time evolution of initial damage events has yet to be realized. Here we report on the absolute measurement of proton bursts as short as 3.5±0.7 ps from laser solid target interactions for this purpose. Our results verify that laser-driven ion acceleration can deliver interaction times over a factor of hundred shorter than those of state-of-the-art accelerators optimized for high instantaneous flux. Furthermore, these observations draw ion interaction physics into the field of ultrafast science, opening the opportunity for quantitative comparison with both numerical modelling and the adjacent fields of ultrafast electron and photon interactions in matter.
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| 8. |
- Green, J. S., et al.
(författare)
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Enhanced proton flux in the MeV range by defocused laser irradiation
- 2010
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Thin Al foils (50 nm and 6 mu m) were irradiated at intensities of up to 2x10(19) W cm(-2) using high contrast (10(8)) laser pulses. Ion emission from the rear of the targets was measured using a scintillator-based Thomson parabola and beam sampling 'footprint' monitor. The variation of the ion spectra and beam profile with focal spot size was systematically studied. The results show that while the maximum proton energy is achieved around tight focus for both target thicknesses, as the spot size increases the ion flux at lower energies is seen to peak at significantly increased spot sizes. Measurements of the proton footprint, however, show that the off-axis proton flux is highest at tight focus, indicating that a previously identified proton deflection mechanism may alter the on-axis spectrum. One-dimensional particle-in-cell modelling of the experiment supports our hypothesis that the observed change in spectra with focal spot size is due to the competition of two effects: decrease in laser intensity and an increase in proton emission area.
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| 9. |
- Schwab, M. B., et al.
(författare)
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Visualization of relativistic laser pulses in underdense plasma
- 2020
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Ingår i: Physical Review Accelerators and Beams. - 2469-9888. ; 23:2
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental evidence of relativistic electron-cyclotron resonances (RECRs) in the vicinity of the relativistically intense pump laser of a laser wakefield accelerator (LWFA). The effects of the RECRs are visualized by imaging the driven plasma wave with a few-cycle, optical probe in transverse geometry. The probe experiences strong, spectrally dependent and relativistically modified birefringence in the vicinity of the pump that arises due to the plasma electrons' relativistic motion in the pump's electromagnetic fields. The spectral birefringence is strongly dependent on the local magnetic field distribution of the pump laser. Analysis and comparison to both 2D and 3D particle-in-cell simulations confirm the origin of the RECR effect and its appearance in experimental and simulated shadowgrams of the laser-plasma interaction. The RECR effect is relevant for any relativistic, magnetized plasma and in the case of LWFA could provide a nondestructive, in situ diagnostic for tracking the evolution of the pump's intensity distribution with propagation through tenuous plasma.
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| 10. |
- Xu, M. H., et al.
(författare)
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Enhancement of ion generation in femtosecond ultraintense laser-foil interactions by defocusing
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:8
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Tidskriftsartikel (refereegranskat)abstract
- A simple method to enhance ion generation with femtosecond ultraintense lasers is demonstrated experimentally by defocusing laser beams on target surface. When the laser is optimally defocused, we find that the population of medium and low energy protons from ultra-thin foils is increased significantly while the proton cutoff energy is almost unchanged. In this way, the total proton yield can be enhanced by more than 1 order, even though the peak laser intensity drops. The depression of the amplified spontaneous emission (ASE) effect and the population increase of moderate-energy electrons are believed to be the main reasons for the effective enhancement. (C) 2012 American Institute of Physics. [doi:10.1063/1.3688027]
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