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Electron acceleration to very high energies is achieved in a single step by injecting electrons into a ‘wake’ of charge created in a 10-metre-long plasma by speeding long proton bunches.

Plasma wakefield accelerators promise compact, affordable future particle accelerators, but require deposition of enormous energy into a small volume. Here, the authors measure and simulate how this energy transfers from the wake into surrounding plasma, a process that ultimately governs the accelerator’s repetition rate.

The first operation of the European X-ray free-electron laser facility accelerator based on superconducting technology is reported. The maximum electron energy is 17.5 GeV. A laser average power of 6 W is achieved at a photon energy of 9.3 keV.

Extraction of ultra-low emittance bunches is an issue to be addressed for future applications of plasma wakefield accelerators. Here, the authors show that the field structure of the plasma could be suitable for this, by measuring the field's longitudinal variation produced by a relativistic electron bunch.

Laser-plasma accelerators can produce giga electronvolt energy electrons over centimetre scales, but their properties depend on the initial injection into the accelerator. Corde et al.study self-injection of electrons into the plasma wake and identify both transverse and longitudinal injection mechanisms.

A laser-plasma electron beam generated using active energy compression demonstrates reduction in energy spread and jitter by an order of magnitude to below the permille level, comparable with modern radio-frequency accelerators.

Few-femtosecond synchronization at free-electron lasers is key for nearly all experimental applications, stable operation and future light source development. Here, Schulz et al. demonstrate all-optical synchronization of the soft X-ray FEL FLASH to better than 30 fs and illustrate a pathway to sub-10 fs.

A particle accelerator that is two orders of magnitude more efficient than conventional radio-frequency accelerators is described in which positrons (rather than electrons) at the front of a bunch transfer their energy to a substantial number of positrons at the rear of the same bunch by exciting a wakefield in the plasma.

Plasma accelerators driven by particle beams are a promising technology, but the acceleration distance and energy gain are strongly limited by head erosion in a high-ionization-potential gas. Here the authors observe up to 130% energy boost in a self-focused electron beam, with limited head erosion.

Relativistic 35 MeV electron bunches with charges of 60 pC are accelerated in a terahertz-wave-driven dielectric waveguide. When the terahertz pulse energy is 0.8 μJ, an accelerating gradient of 2 MeV m⁻¹ and energy gain of 10 keV are achieved.

To develop plasma wakefield acceleration into a compact and affordable replacement for conventional accelerators, beams of charged particles must be accelerated at high efficiency in a high electric field; here this is demonstrated for a bunch of charged electrons ‘surfing’ on a previously excited plasma wave.

A laser-based scheme for the simultaneous generation of two temporally synchronized electron beams with individually adjustable energies offers new opportunities for ultrafast pump–probe experiments.

Particle accelerators based on laser- or electron-driven plasma waves promise compact sources for relativistic electron bunches. Here, Kurz and Heinemann et al. demonstrate a hybrid two-stage configuration, combining the individual features of both accelerating schemes.

Wakefield accelerators are a cheaper and compact alternative to conventional particle accelerators for high-energy physics and coherent x-ray sources. Here, the authors demonstrate a field gradient in excess of a gigaelectron-volt-per-metre using a terahertz-frequency wakefield supported by a dielectric lined-waveguide.

Higher beam quality and stability are desired in laser-plasma accelerators for their applications in compact light sources. Here the authors demonstrate in laser plasma wakefield electron acceleration that the beam loading effect can be employed to improve beam quality by controlling the beam charge.

The energy loss of ions in plasma is a challenging issue in inertial confinement fusion and many theoretical models exist on ion-stopping power. Here, the authors use laser-generated plasma probed by accelerator-produced ions in experiments to discriminate various ion stopping models near the Bragg peak.

The potential to generate pulsed electron beams with charge distributions tailored in all three dimensions could revolutionize high-speed electron diffraction. A demonstration of a highly coherent pulse electron beam that can be arbitrarily tailored in two dimensions is a step towards this goal.

X-ray free-electron lasers, important light sources for materials research, suffer from shot-to-shot fluctuations that necessitate complex diagnostics. Here, the authors apply machine learning to accurately predict pulse properties, using parameters that can be acquired at high-repetition rates.

Synchrotron radiation sources based on a combination of laser plasma accelerators and magnetic undulator have been limited in terms of brightness. Here, Andriyash et al.propose to use a sub-millimetre nano-wire array as a laser-plasma undulator that could produce bright, collimated and tunable X-ray pulses.

A new conceptual approach to light generation involving an ensemble of light-emitting charges may result in more compact superradiant light sources.

Understanding the ultrafast dynamics of materials under extreme conditions is challenging. Here the authors use a femtosecond betatron X-ray source to investigate the solid to dense plasma phase transition in copper using XAS with unprecedented time resolution.

Electrons moving in strongly curved paths emit radiation that is used in free-electron laser designs. Here, the authors demonstrate the inverse force principle, where a laser light field is used in a compact experimental design to accelerate electrons to produce high-quality electron beams.

Understanding asteroid materials is critical for determining deflection methods for planetary defense. Here the authors show, via experiments performed in High-Radiation to Materials facility at CERN, that iron-rich asteroid materials can absorb more energy without structural failure than standard material parameters would suggest.

Pulsed electron beams with ultrafast duration are desirable to study atomic processes occurring over the natural time scales of electronic motion. Here the authors demonstrate the generation of electron pulses down to attosecond time scales by using optical gating and streaking method.

EDI048 is a gastrointestinal-targeted Cryptosporidium PI(4)K inhibitor that undergoes a predictable metabolism and limits systemic exposure without compromising its anti-parasitic activity.

The one-dimensional laser cooling of positronium enables testing of quantum electrodynamics and could realize Bose–Einstein condensation in positronium.

It is desirable to improve spatiotemporal control of light generated by synchrotron user facilities or table-top X-ray sources. Here the authors demonstrate manipulation of hard X-rays using microelectro mechanical systems (MEMS) oscillators on timescales of 300 ps, approaching the synchrotron pulse width.

Scientists demonstrate a Compton-based electromagnetic source based on a laser-plasma accelerator and a plasma mirror. The source generates a broadband spectrum of X-rays and is 10,000 times brighter than Compton X-ray sources based on conventional accelerators.

The influence of spin–orbit coupling on itinerant electrons underlies the formation of spin–orbit Mott states. Here, the authors demonstrate a temperature-hysteretic cascade between charge-ordered phases stabilized by localized 5dspin–orbit Mott dimer states in metallic iridium ditelluride.

Electron–positron pair plasma—a state of matter with a complete symmetry between negatively and positively charged particles—are found in many astrophysical object. Here, the authors use high-power laser to create an ion-free electron–positron plasma in the laboratory.

Modifiers of diverse materials exhibit structures or compositions that differ from a solute molecule but often contain similar functional motifs that facilitate molecular recognition for modifier binding to crystal surfaces. Here the authors examine the intrinsic capability of tautomers, or structural isomers, to operate as crystal growth inhibitors.’

A silicon-on-insulator device combining two four-wave-mixing photon-pair sources in an interferometer with a reconfigurable phase shifter is used to create and manipulate non-degenerate or degenerate, path-entangled or path-unentangled photon pairs. A quantum interference visibility of nearly 100% is observed on-chip. This device is a first step towards fully integrated quantum technologies.

Researchers use single-cycle THz pulses from an optical laser to extend streaking techniques of attosecond metrology to measure the temporal profile and arrival time of individual FEL pulses with ∼5 fs precision.

Ten years after the discovery of the Higgs boson, the ATLAS  experiment at CERN probes its kinematic properties with a significantly larger dataset from 2015–2018 and provides further insights on its interaction with other known particles.

Attosecond time–energy characterization of pulses generated by the Linac Coherent Light Source (LCLS) X-ray free-electron laser is enabled by angular streaking measurements.

The most up-to-date combination of results on the properties of the Higgs boson is reported, which indicate that its properties are consistent with the standard model predictions, within the precision achieved to date.

Using terahertz spectroscopy and ultrafast electron diffraction, the paper shows how the DC conductivity of warm dense matter depends on material phase. This provides insight to how electron scattering processes impact conductivity in this regime.

The use of light in driving the magnetization of materials has great technological potential, as well as allowing for insights into the fast dynamics of magnetic systems. Here, the authors combine CrI₃, a van der Waals magnet, with WSe₂, and demonstrate all optical switching of the resulting heterostructure.

The CMS Collaboration reports the study of three simultaneous hard interactions between quarks and gluons in proton–proton collisions. This manifests through the concurrent production of three J/ψ mesons, which consist of a charm-quark–antiquark pair.

Laser-plasma particle accelerators offer much higher acceleration than conventional methods, which could enable high-energy applications; here two separate accelerator stages, driven by two independent lasers, are coupled using plasma-based optics.

A method to control the polarization of a Compton gamma-ray beam is developed. By using a free-electron laser oscillator with two helical undulator magnets of opposite helicities, Compton gamma-ray beams with a polarizability of 0.97 are generated.

Free-electron lasers offer exciting new possibilities for X-ray studies on ultrafast timescales, but their shot-to-shot variability requires new diagnostic tools. Using a plasma switch cross-correlator, Riedel et al. present a single-shot online diagnostic to retrieve the duration of extreme ultraviolet pulses.