Experimental setup for high-resolution characterization of crystal optics for coherent X-ray beam applications.

Stanford Synchrotron Radiation Lightsource serves a wide scientific community with its variety of X-ray capabilities. Recently, a wiggler X-ray source located at beamline 10-2 has been employed to perform high-resolution rocking curve imaging (RCI) of diamond and silicon crystals. X-ray RCI is invaluable for the development of upcoming cavity-based X-ray sources at SLAC, including the cavity-based X-ray free-electron laser and X-ray laser oscillator. In this paper, the RCI apparatus is described and experimental results are provided to validate its design. Future improvements of the setup are also discussed.

Laguerre-Gaussian Mode Laser Heater for Microbunching Instability Suppression in Free-Electron Lasers.

Microbunching instability (MBI) driven by beam collective effects is known to be detrimental to high-brightness storage rings, linacs, and free-electron lasers (FELs). One known way to suppress this instability is to induce a small amount of energy spread to an electron beam by a laser heater. The distribution of the induced energy spread greatly affects MBI suppression and can be controlled by shaping the transverse profile of the heater laser. Here, we present the first experimental demonstration of effective MBI suppression using a LG_{01} transverse laser mode and compare the improved results with respect to traditional Gaussian transverse laser mode at the Linac Coherent Light Source. The effects on MBI suppression are characterized by multiple downstream measurements, including longitudinal phase space analysis and coherent radiation spectroscopy. We also discuss the role of LG_{01} shaping in soft x-ray self-seeded FEL emission, one of the most advanced operation modes of a FEL for which controlled suppression of MBI is critical.

X-ray free-electron laser wavefront sensing using the fractional Talbot effect.

Wavefront sensing at X-ray free-electron lasers is important for quantitatively understanding the fundamental properties of the laser, for aligning X-ray instruments and for conducting scientific experimental analysis. A fractional Talbot wavefront sensor has been developed. This wavefront sensor enables measurements over a wide range of energies, as is common on X-ray instruments, with simplified mechanical requirements and is compatible with the high average power pulses expected in upcoming X-ray free-electron laser upgrades. Single-shot measurements were performed at 500 eV, 1000 eV and 1500 eV at the Linac Coherent Light Source. These measurements were applied to study both mirror alignment and the effects of undulator tapering schemes on source properties. The beamline focal plane position was tracked to an uncertainty of 0.12 mm, and the source location for various undulator tapering schemes to an uncertainty of 1 m, demonstrating excellent sensitivity. These findings pave the way to use the fractional Talbot wavefront sensor as a routine, robust and sensitive tool at X-ray free-electron lasers as well as other high-brightness X-ray sources.

Refractive Guide Switching a Regenerative Amplifier Free-Electron Laser for High Peak and Average Power Hard X Rays.

We present an x-ray regenerative amplifier free-electron laser design capable of producing fully coherent hard x-ray pulses across a broad tuning range at a high steady state repetition rate. The scheme leverages a strong undulator taper and an apertured diamond output-coupling cavity crystal to produce both high peak and average spectral brightness radiation that is 2 to 3 orders of magnitude greater than conventional single-pass self-amplified spontaneous emission free-electron laser amplifiers. Refractive guiding in the postsaturation regime is found to play a key role in passively controlling the stored cavity power. The scheme is explored both analytically and numerically in the context of the Linac Coherent Light Source II High Energy upgrade.

Atendimento a saúde por bombeiros: dificuldades encontradas que implicam na assistência a população / Health care from firefighters: the faced difficulties that impact in the population's assistance / Cuidado de la salud para los bomberos: las dificultades que entrañan asistencia en la población

Objetivo: Identificar quais as percepções dos bombeiros quanto ao atendimento pré-hospitalar, suas principais dificuldades e riscos encontrados na prestação do atendimento em saúde. Métodos: Trata-se de uma pesquisa do tipo descritiva com abordagem qualitativa, em que se utilizou de uma entrevista semiestruturada guiada por roteiro. Resultados: Os depoimentos dos bombeiros foram sintetizados em três unidades temáticas, assim denominadas: A percepção de bombeiros sobre o atendimento préhospitalar (APH); A necessidade do enfermeiro no APH realizado pela equipe do corpo de bombeiros e a Insegurança versus riscos inerentes do atendimento pré-hospitalar. Conclusão: Através de todo o exposto espera-se, contribuir para a construção do conhecimento e reflexão quanto a percepção e atuação do corpo de bombeiros no APH e a importância de integrar profissionais de saúde na equipe de resgate, assim como investir na capacitação destes e em materiais de qualidade que possibilitem segurança aos profissionais e pacientes

Objetivo: Identificar las percepciones de fuego como la atención prehospitalaria, sus principales dificultades y riesgos encontrados en la prestación de asistencia sanitaria. Métodos: Este es un estudio de enfoque cualitativo descriptivo, que utilizó una entrevista visita guiada semiestructurada. Resultados: El testimonio de los bomberos fueron sintetizados en tres unidades temáticas, los llamados: La percepción de fuego en la atención pre-hospitalaria; La necesidad de enfermeras en APH realizadas por el equipo del cuerpo de bomberos y la inseguridad frente a los riesgos de la atención pre-hospitalaria. Conclusión: Se espera que a través de todo lo anterior, para contribuir a la construcción del conocimiento y la reflexión como las operaciones de percepción y del cuerpo de bomberos de la APH y la importancia de la integración de los profesionales sanitarios en el equipo de rescate, así como invertir en la formación de estos y materiales de calidad que permiten a los profesionales de seguridad y los pacientes

Objective: The research's purpose has been to identify the firefighters' perceptions with regards to the prehospital care, as well as their own main difficulties and risks when performing health care. Methods: This is a descriptive research with a qualitative approach, which used scripted semi-structured interviews for data collection. Results: The firefighters' statements were synthesized in three thematic units, as follows: "The firefighters' perceptions about prehospital care; "The requirement of nurses in the prehospital care performed by firefighters"; and "Insecurity versus prehospital care inherent risks". Conclusion: It is expected that this study may contribute to further increase the knowledge of this field, and the careful thinking about the firefighters' perception and performance towards prehospital care. Furthermore, this study aims to emphasize the importance of integrating health professionals into the rescue team, as well as investing in their training and in quality materials that provide security to both professionals and patients

Self-Assembled Heterostructures: Selective Growth of Metallic Nanoparticles on V2 -VI3 Nanoplates.

Precise control of the selective growth of heterostructures with specific composition and functionalities is an emerging and extremely challenging topic. Here, the first investigation of the difference in binding energy between a series of metal-semiconductor heterostructures based on layered V2 -VI3 nanostructures is investigated by means of density functional theory. All lateral configurations show lower formation energy compared with that of the vertical ones, implying the selective growth of metal nanoparticles. The simulation results are supported by the successful fabrication of self-assembled Ag/Cu-nanoparticle-decorated p-type Sb2 Te3 and n-type Bi2 Te3 nanoplates at their lateral sites through a solution reaction. The detailed nucleation-growth kinetics are well studied with controllable reaction times and precursor concentrations. Accompanied by the preserved topological structure integrity and electron transfer on the semiconductor host, exceptional properties such as dramatically increased electrical conductivity are observed thanks to the pre-energy-filtering effect before carrier injection. A zigzag thermoelectric generator is built using Cu/Ag-decorated Sb2 Te3 and Bi2 Te3 as p-n legs to utilize the temperature gradient in the vertical direction. Synthetic approaches using similar chalcogenide nanoplates as building blocks, as well as careful control of the dopant metallic nanoparticles or semiconductors, are believed to be broadly applicable to other heterostructures with novel applications.