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High intensity, high-repetition rate (HRR) lasers, that is lasers that can operate on the order of 1 Hz or faster, are quickly coming on-line around the world. High intensity lasers have long been an impactful tool in high energy density (HED) science since they are capable of creating matter at extreme temperatures and pressures relevant to this field. The advent of HRR technology enhances to this capability since HRR enables these types of these experiments to be performed faster, thus leading to an acceleration in the rate of learning in fundamental HED science. However, in order to use the full potential of HRR systems, high repetition rate diagnostics in addition to real-time analysis tools must be developed to process experimental measurements and outputs at a rate that matches the laser. Towards this goal, we present an automated machine learning based analysis for a synthetic X-ray spectrometer, which is a common diagnostic in HED experiments.

Consumption of L-Theanine (L-THE) has been associated with a sensation of relaxation, as well as a reduction of stress. However, these physiological responses have yet to be elucidated in humans where L-THE is compared alongside food or as a functional ingredient within the food matrix. The aim of this study was to determine the physiological responses of a single intake of a potential functional food product (mango sorbet) containing L-THE (ms-L-THE, 200 mgw/w) in comparison to a flavour and colour-matched placebo (ms). Eighteen healthy male participants were recruited in this randomised, double-blind, placebo-controlled trial. The participants were required to consume ms-L-THE or placebo and their blood pressure (BP) (systolic and diastolic), heart rate (HR), and heart rate variability (HRV) were monitored continuously over 90 minutes. Eleven males (age 27.7 ± 10.8 years) completed the study. Changes in area under the curve for systolic and diastolic blood pressure and HRV over the 90 minute observation period indicated no differences between the three conditions (all p &gt, 0.05) or within individual groups (all p &gt, 0.05). The values for heart rate were also not different in the placebo group (p = 0.996) and treatment group (p = 0.066), while there was a difference seen at the baseline (p = 0.003). Based on the findings of this study, L-THE incorporated in a food matrix (mango sorbet) demonstrated no reduction in BP or HR and showed no significant parasympathetic interaction as determined by HRV high-frequency band and low-frequency/high-frequency ratio. Further studies should be focussed towards the comparison of pure L-THE and incorporation within the food matrix to warrant recommendations of L-THE alongside food consumption.

Picosecond-scale laser–matter interactions using compound parabolic concentrators have demonstrated strongly relativistic ponderomotive effects with ∼ 10 × increase in x-ray source brightness, positron production and multi-MeV proton acceleration versus flat targets, using a marginally relativistic intensity laser.

The dynamics of magnetized flows is of great interest to the astrophysics community as the formation and long collimation distances of jets in accretion systems are still open questions. In many of these systems, the background magnetic field is parallel to the jet propagation direction. Recent experiments [1] performed at the Jupiter Laser Facility investigated the effects of imposing a background magnetic field aligned with a collimated jet. Plastic cone targets were irradiated by a long-pulse laser as shown schematically in Fig. 1a. When the shock emerges from the backside of the cone, accelerated material accumulates on axis producing a collimated flow. Figure 1b demonstrates the collimation of the plasma without the background field and the disruption of the flow when applying a 5 T field. Experimental results will be discussed in detail with supporting numerical work describing the mechanisms causing the jet disruption.

Nonlinear optical phenomena in semiconductors present several fundamental problems in modern optics that are of great importance for the development of optoelectronic devices. In particular, the details of photo-induced lattice dynamics at early time-scales prior to carrier recombination remain poorly understood. We demonstrate the first integrated measurements of both optical and structural, material-dependent quantities while also inferring the bulk impulsive strain profile by using high spatial-resolution time-resolved x-ray scattering (TRXS) on bulk crystalline gallium arsenide. Our findings reveal distinctive laser-fluence dependent crystal lattice responses, which are not described by previous TRXS experiments or models. The initial linear expansion of the crystal upon laser excitation stagnates at a laser fluence corresponding to the saturation of the free carrier density before resuming expansion in a third regime at higher fluences where two-photon absorption becomes dominant. Our interpretations of the lattice dynamics as nonlinear optical effects are confirmed by numerical simulations and by additional measurements in an n-type semiconductor that allows higher-order nonlinear optical processes to be directly observed as modulations of x-ray diffraction lineshapes.

Using a strain-rosette, we demonstrate the existence of transverse strain using time-resolved x-ray diffraction from multiple Bragg reflections in laser-excited bulk gallium arsenide. We find that anisotropic strain is responsible for a considerable fraction of the total lattice motion at early times before thermal equilibrium is achieved. Our measurements are described by a new model where the Poisson ratio drives transverse motion, resulting in the creation of shear waves without the need for an indirect process such as mode conversion at an interface. Using the same excitation geometry with the narrow-gap semiconductor indium antimonide, we detected coherent transverse acoustic oscillations at frequencies of several GHz.

The Sector 7 undulator beamline (7 ID) of the Advanced Photon Source (APS) is dedicated to time-resolved X-ray research [1] . Silicon avalanche photodiodes (APDs) are used as the primary point detector for time-resolved Bragg diffraction experiments for their fast recovery time ( [2] . Common practice has been to attenuate the monochromatic beam entering the experimental hutch to an appropriately low flux [3] . For these high-flux experiments, an APD operated in proportional mode is a better detector choice due to a large dynamic range and linearity. With the ZT4212 ZTEC, EPICS based oscilloscope, the operating procedure to use an APD in proportional mode has been improved. This article shows the setup and operating procedure for this oscilloscope and demonstrates its application to measuring time-resolved rocking curves of laser excited semiconductors.