Pair-Production in the Non-Perturbative Regime

Quantum Vacuum Research Unit FOR/2783 Permalink
The direct electron-positron pair creation via quantum-vacuum fluctuations is one of the most intriguing physics processes that remain untested under laboratory conditions. By applying a strong electric field above the Schwinger critical limit of 1.3$\times$10$^{18}$ V/m, the virtual pairs from the quantum fluctuations can be turned into observables. However, despite the recent advances in the peak power of high-intensity lasers, the critical limit is still far beyond achievable.

Objectives: To develop a functional experiment and a detection system within the ATLAS-3000 laser system at the Centre for Advanced Laser Applications (CALA), capable of both generating and diagnosing electron-positron pairs originating from these quantum-vacuum fluctuations.

More about the topic:

1. F. C. Salgado, K. Grafenstein, A. Golub, A. Doepp, A. Eckey, D. Hollatz, C. Mueller, A. Seidel, D. Seipt, S. Karsch, M. Zepf, “Towards pair production in the non-perturbative regime,” New J. Phys. 23, 2021
   doi:10.1088/1367-2630/ac2921
2. B. Kettle, D. Hollatz, E. Gerstmayr, G. M. Samarin, et al., “A laser-plasma platform for photon-photon physics: the two photon Breit-Wheeler process,” New J. Phys. 23, 2021
   doi:10.1088/1367-2630/ac3048
3. H. Abramowicz, et al., “Conceptual design report for the LUXE experiment,” Eur. Phys. J.: Spec. Top. 230, 2021
   doi:10.10.1109/10.1140/epjs/s11734-021-00249-z

Detector Development

Particle Detectors for SF-QED Experiments
Detecting signatures of strong-field Quantum Electrodynamics (QED) processes represents a significant experimental challenge. This challenge arises from the inherent high background noise levels, primarily generated by x-rays and $\gamma$-photons, prevalent in experiments involving high-energy electron beams. Consequently, detectors used for this type of experiment need to exhibit high sensitivity to single-particle hits while effectively rejecting background noise spanning several orders of magnitude.

Objectives: To design a single-particle detection system for upcoming strong- field QED experiments E-320 at FACET-II at the SLAC National Laboratory and the FOR2783 at the Centre for Advanced Laser Applications (CALA).

More about the topic:

1. F. C. Salgado, N. Cavanagh, M. Tamburini, D. W. Storey, et al., “Single particle detection system for strong-field QED experiments,” New J. Phys. 24, 2022
   doi:10.1088/1367-2630/ac4283
2. F. C. Salgado, “Design of a single–particle detection system for strong–field QED experiments,” Dissertation, Friedrich-Schiller-Universität Jena, 2023
   Link to thesis

Laser-Driven Particle Acceleration

Optimization and characterization of energy, charge, bandwidth of laser-accelerated electron beams (LWFA)
Laser wakefield accelerators (LWFAs) represent an effective alternative to conventional accelerators, primarily to their ability to accelerate electron bunches up to GeV energies within a compact setup spanning just a few centimeters in stark contrast to the several kilometers required for linear accelerators.

Significant progress on LWFA have been made in the recent years. However, achieving beam quality comparable to that of conventional accelerators still necessitates ongoing research into critical parameters, such as beam energy and bandwidth, emittance, and stability.

Objectives: Optimization and characterization of beam parameters, with the goal of achieving a sufficient level of beam quality for the next generation of compact accelerators. These advancements hold significant potential for utilization as drivers in free-electron lasers (FELs), particle colliders, Thomson sources, and numerous other applications.

More about the topic:

1. K. v. Grafenstein, F. M. Foerster, F. Haberstroh, D. Campbell, F. Irshad, F. C. Salgado, G. Schilling, E. Travac, N. Weisse, M. Zepf, A. Doepp, S. Karsch , “Laser-accelerated electron beams at 1 GeV using optically-induced shock injection,” Sci. Rep. 13, 2023
   doi:10.1038/s41598-023-38805-3
2. A. J. Gonsalves, K. Nakamura, J. Daniels, C. Benedetti, C. Pieronek, et al., “Petawatt Laser Guiding and Electron Beam Acceleration to 8 GeV in a Laser-Heated Capillary Discharge Waveguide,” Phys. Rev. Lett. 122, 2019
   doi:10.1103/PhysRevLett.122.084801