Simultaneous laser-driven x-ray and two-photon fluorescence imaging of atomizing sprays

In this Letter, we report for the first time, to the best of our knowledge, the possibility of visualizing an atomizing spray by simultaneously recording x-ray absorption and two-photon laser-induced fluorescence imaging. This unique illumination/detection scheme is made possible due to the use of soft x rays emitted from a laser-driven x-ray source. An 800 mJ laser pulse of 38 fs duration is used to generate an x-ray beam with up to 4 × 108 photons ranging from 1 to 10 keV, allowing projection radiography of water jets generated by an automotive port fuel injector. In addition, a fraction of the laser pulse (∼10mJ) is employed to form a light sheet and to induce two-photon fluorescence in a dye added to the water. The resulting high-contrast fluorescence images provide fine details of the spray structure, with reduced blur from multiple light scattering, while the integrated liquid mass is extracted from the x-ray radiography. In this proof of principle, we show that the combination of these two highly complementary techniques, in both the visible and soft x-ray regimes, is very promising for future characterization of challenging spray, as well as for further understanding of the physics of liquid atomization

Start-to-end simulations of plasma-wakefield acceleration using the MAX IV Linear Accelerator

Plasma-wakefield acceleration (PWFA) relies on the interaction between intense particle bunches and plasma for reaching higher accelerating gradients than what is possible with conventional radio-frequency technology. Using ultra-relativistic beam drivers allows for long acceleration lengths and have potential applications such as energy booster stages for synchrotron light sources or linear colliders and generating ultra-high-brightness beams from the background plasma. In this article, we present start-to-end simulations of the MAX IV Linear Accelerator as part of our investigations into the feasibility of using the linac for a PWFA experiment. We find that PWFA appears to be a viable application for the linac. A part of this conclusion is based on our finding that the general properties of the bunch compressor type employed in the MAX IV linac are well-suited for efficient generation of PWFA-optimized bunch current profiles, both for single- and double-bunch beams

Emittance preservation in a plasma-wakefield accelerator

Radio-frequency particle accelerators are engines of discovery, powering high-energy physics and photon science, but are also large and expensive due to their limited accelerating fields. Plasma-wakefield accelerators (PWFAs) provide orders-of-magnitude stronger fields in the charge-density wave behind a particle bunch travelling in a plasma, promising particle accelerators of greatly reduced size and cost. However, PWFAs can easily degrade the beam quality of the bunches they accelerate. Emittance, which determines how tightly beams can be focused, is a critical beam quality in for instance colliders and free-electron lasers, but is particularly prone to degradation. We demonstrate, for the first time, emittance preservation in a high-gradient and high-efficiency PWFA while simultaneously preserving charge and energy spread. This establishes that PWFAs can accelerate without degradation—an essential step toward energy boosters in photon science and multistage facilities for compact high-energy particle colliders

Evolution of sex-specific pace-of-life syndromes: genetic architecture and physiological mechanisms

Sex differences in life history, physiology, and behavior are nearly ubiquitous across taxa, owing to sex-specific selection that arises from different reproductive strategies of the sexes. The pace-of-life syndrome (POLS) hypothesis predicts that most variation in such traits among individuals, populations, and species falls along a slow-fast pace-of-life continuum. As a result of their different reproductive roles and environment, the sexes also commonly differ in pace-of-life, with important consequences for the evolution of POLS. Here, we outline mechanisms for how males and females can evolve differences in POLS traits and in how such traits can covary differently despite constraints resulting from a shared genome. We review the current knowledge of the genetic basis of POLS traits and suggest candidate genes and pathways for future studies. Pleiotropic effects may govern many of the genetic correlations, but little is still known about the mechanisms involved in trade-offs between current and future reproduction and their integration with behavioral variation. We highlight the importance of metabolic and hormonal pathways in mediating sex differences in POLS traits; however, there is still a shortage of studies that test for sex specificity in molecular effects and their evolutionary causes. Considering whether and how sexual dimorphism evolves in POLS traits provides a more holistic framework to understand how behavioral variation is integrated with life histories and physiology, and we call for studies that focus on examining the sex-specific genetic architecture of this integration

Relative alignment within the MAX IV 3 GeV storage ring magnet blocks

Unlike the discrete magnet scheme of previous 3rd generation light sources, the magnet elements of the MAX IV storage rings are integrated in precision-machined magnet blocks. By analyzing the rotating coil measurements made by the magnet suppliers, we determined the relative alignment between consecutive magnet elements, which was foundto be <10 μm RMS for all magnet block typesin both horizontal and vertical direction. This article presents our analysis and results for the full magnet production series

Forests on drained agricultural peatland are potentially large sources of greenhouse gases – insights from a full rotation period simulation

The CoupModel was used to simulate a Norway spruce forest on fertile drained peat over 60 years, from planting in 1951 until 2011, describing abiotic, biotic and greenhouse gas (GHG) emissions (CO₂ and N₂O). By calibrating the model against tree ring data a “vegetation fitted” model was obtained by which we were able to describe the fluxes and controlling factors over the 60 years. We discuss some conceptual issues relevant to improving the model in order to better understand peat soil simulations. However, the present model was able to describe the most important ecosystem dynamics such as the plant biomass development and GHG emissions. The GHG fluxes are composed of two important quantities, the spruce forest carbon (C) uptake, 413 g C m⁻² yr⁻¹ and the decomposition of peat soil, 399 g C m⁻² yr⁻¹. N₂O emissions contribute to the GHG emissions by up to 0.7 g N m⁻² yr⁻¹, corresponding to 76 g C m⁻² yr⁻¹. The 60-year old spruce forest has an accumulated biomass of 16.0 kg C m⁻² (corresponding to 60 kg CO₂ m⁻²). However, over this period, 26.4 kg C m⁻² (97 kg CO₂eq m⁻²) has been added to the atmosphere, as both CO₂ and N₂O originating from the peat soil and, indirectly, from forest thinning products, which we assume have a short lifetime. We conclude that after harvest at an age of 80 years, most of the stored biomass carbon is liable to be released, the system having captured C only temporarily and with a cost of disappeared peat, adding CO₂ to the atmosphere

MAX IV Photocathode Gun Laser System Specification and Diagnostics

The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG