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The Kamioka Gravitational wave detector (KAGRA) cryogenic gravitational-wave observatory has commenced joint observations with the worldwide gravitational wave detector network. Precise calibration of the detector response is essential for accurately estimating parameters of gravitational wave sources. A photon calibrator is a crucial calibration tool used in laser interferometer gravitational-wave observatory, Virgo, and KAGRA, and it was utilized in joint observation 3 with GEO600 in Germany in April 2020. In this paper, KAGRA implemented three key enhancements: a high-power laser, a power stabilization system, and remote beam position control. KAGRA employs a 20 W laser divided into two beams that are injected onto the mirror surface. By utilizing a high-power laser, the response of the detector at kHz frequencies can be calibrated. To independently control the power of each laser beam, an optical follower servo was installed for power stabilization. The optical path of the photon calibrator's beam positions was controlled using pico-motors, allowing for the characterization of the detector's rotation response. Additionally, a telephoto camera and quadrant photodetectors were installed to monitor beam positions, and beam position control was implemented to optimize the mirror response. In this paper, we discuss the statistical errors associated with the measurement of relative power noise. We also address systematic errors related to the power calibration model of the photon calibrator and the simulation of elastic deformation effects using finite element analysis. Ultimately, we have successfully reduced the total systematic error from the photon calibrator to 2.0%. [ABSTRACT FROM AUTHOR]

We performed a scientometric analysis of Chaos papers from 1991 to 2019, applying a careful disambiguation process for identifying the authors correctly. First, we used standard scientometric tools based on descriptive statistics. This analysis enabled us to compute productivity and the degree of collaboration. The evolution in the number of authors, countries, and topics per article has an increasing trend. An analysis of the citations considering their temporal mean number exhibits a growing tendency in time. Second, we dealt with Lotka–Zipf's law considering the rank distributions of 15 datasets. We found that the sum of Crossref citations by country was the only dataset for which the power-law was the only plausible distribution. Next, we examined the networks of authors, countries, and topics, going from the simplest case of undirected and unweighted networks to the general case of weighted and directed networks and assigning a weight to the individual nodes. Based on the networks' topology and features, we introduced diversity, collaboration, influence, and productivity measures and found a significant increase in the diversity of all the considered networks (authors, countries, and topics) but manifesting a very different network structure. The computation of typical network quantities combined with the communities' identification reveals the presence of several hubs and the existence of various communities that encompass nodes of all the continents in the case of countries. Finally, using the most general networks, it was possible to compute influence and productivity indexes to find the USA, China, and Germany's leadership inside the network. [ABSTRACT FROM AUTHOR]

This paper presents the simulation results of a multistage depressed collector for a MW-class gyrotron. The energy distribution of spent electrons is obtained by a beam–wave interaction code. By increasing the number of depressed electrodes, the maximum collection efficiency can be increased to 81% with a low percentage of backstreaming 0.04% with regard to a four-stage depressed collector. By considering the secondary electron emission, the effects of different kinds of secondary electrons are simulated in the CST software, which is developed by Computer Simulation Technology Company in Germany. In order to reduce bad effects of secondary electrons, the structure of the fourth depressed electrode has been adjusted to form a slope. The axial length and slant angle of the slope have been optimized. The results indicate that the collection efficiency can exceed 70% and the percentage of backstreaming is less than 1%. Besides, in view of the limited power capacity of the collector wall, a magnetic field sweeping system has been introduced. The maximum power density is reduced to 392 W/cm2, and the deposited length of the electron beam trajectory is 470 mm. [ABSTRACT FROM AUTHOR]

The European X-ray Free-Electron Laser Facility in Germany delivers x-ray pulses with femtosecond pulse duration at a repetition rate of up to 4.5 MHz. The free-electron laser radiation is created by the self-amplified spontaneous emission (SASE) process, whose stochastic nature gives rise to shot-to-shot fluctuations in most beam properties, including spectrum, pulse energy, spatial profile, wavefront, and temporal profile. Each spectrum consisting of many spikes varies in width and amplitude that appear differently within the envelope of the SASE spectrum. In order to measure and study the SASE spectrum, the HIgh REsolution hard X-ray single-shot (HIREX) spectrometer was installed in the photon tunnel of the SASE1 undulator beamline. It is based on diamond gratings, bent crystals as a dispersive element, and a MHz-repetition-rate strip detector. It covers a photon energy range of 3 keV–25 keV and a bandwidth of 0.5% of the SASE beam. The SASE spikes are resolved with 0.15 eV separation using the Si 440 reflection, providing a resolving power of 60 000 at a photon energy of 9.3 keV. The measured SASE bandwidth is 25 eV. In this paper, we discuss the design specifications, installation, and commissioning of the HIREX spectrometer. The spectral results using Si (110), Si (111), and C (110) crystals are presented. [ABSTRACT FROM AUTHOR]

Upper Sorbian, an endangered West Slavic language spoken in Germany, is unusual among Slavic languages in having a uvular rhotic /ʀ/. This paper focuses on the gestural configuration and coarticulatory resistance of the uvular rhotic and explores the relation between the articulation and acoustics of this sound. Ultrasound tongue imaging data were collected from six native speakers of Upper Sorbian, who produced /ʀ/ in word-initial, intervocalic, and word-final positions next to the vowels /e a o/. Smoothing Spline ANOVAs were used to compare tongue contours within and across phonetic contexts. Differences in the tongue root and tongue body position were also calculated across environments and compared using a measure of coarticulatory resistance. The results revealed that the sound was produced with considerable tongue root retraction and a uvular-pharyngeal tongue body constriction. The tongue root had a high resistance to coarticulatory effects, while the tongue body did not. The results suggest that the tongue root retraction into the pharyngeal cavity results in observed high F1 and low F2 effects associated with unpalatalized rhotic consonants and may explain perceptual similarity between uvular and alveolar rhotics. Articulatory constraints on the tongue root also account for phonotactic distribution of the rhotics across languages. [ABSTRACT FROM AUTHOR]

The high intensity proton injector for the international accelerator Facility for Antiproton and Ion Research located at GSI-Darmstadt in Germany consists of a pulsed 2.45 GHz microwave ion source, a Low Energy Beam Transport (LEBT), and an electrostatic chopper matching the proton beam to the radio frequency quadrupole. The ion source is based on electron cyclotron resonance plasma production and it has to provide a proton beam at 95 keV energy and up to 100 mA current. The LEBT system with two short solenoids each including two magnetic steerers will transport the proton beam into the compact proton linac, accelerating it to the energy of 68 MeV and serving as the injector of the upgraded heavy ion synchrotron (SIS18). This paper describes the commissioning of the proton injector including beam characterization measurements that have been done at CEA/Saclay in France and is currently at the final commissioning stage. [ABSTRACT FROM AUTHOR]