Harmonic radiation contribution and X-ray transmission at the Small Quantum Systems instrument of European XFEL.

Transmission measurements of the soft X-ray beamline to the Small Quantum Systems (SQS) scientific instrument at the SASE3 undulator of European XFEL are presented. Measurements are reported for a wide range of photon energies (650 eV to 2400 eV), using X-ray gas monitors as well as a bolometric radiometer. The results are in good agreement with simulations for the beam transport and show a transmission of up to 80% over the whole photon energy range. The contribution of second- and third-harmonic radiation of the soft X-ray undulator is determined at selected photon energies by performing transmission measurements using a gas absorber to provide variable attenuation of the incoming photon flux. A comparison of the results with semi-analytic calculations for the generation of free-electron laser pulses in the SASE3 undulator reveals an influence of apertures along the beam transport on the exact harmonic content to be accounted for at the experiment. The second-harmonic content is measured to be in the range of 0.1% to 0.3%, while the third-harmonic contributed a few percent to the SASE3 emission. For experiments at the SQS instrument, these numbers can be reduced through specific selections of the mirror reflection angles.

The Effect of Land-Use Categories on Traffic Noise Annoyance.

Land-use categories are often used to define the exposure limits of national environmental noise policies. Often different guideline values for noise are applied for purely residential areas versus residential areas with mixed-use. Mixed-use includes living plus limited activities through crafts, commerce, trade, agriculture, and forestry activities. This differentiation especially when rating noise from road, railway, and air traffic might be argued by different expectations and therefore noise annoyance in those two categories while scientific evidence is missing. It should be tested on empirically derived data. Surveys from two studies in the state of Tyrol in urban and rural areas were retrospectively matched with spatial data to analyze the potential different influences on noise effects. Using non-parametric tests, the correlation between land-use category on self-reported noise sensitivity and noise annoyance was investigated. Exposure-response for the two analyzed land-use categories showed no significant impact on noise sensitivity and exposure-response relationships for the three traffic noise sources. Including only noise annoyance, there is not sufficient evidence to define different noise policies for those two land-use categories.

Combined annoyance response from railroad and road traffic noise in an alpine valley.

CONTEXT: The aim of this study was to verify the contributing effect in the cases of combined road traffic noise and railroad traffic noise on total noise annoyance. MATERIALS AND METHODS: After opening the four-track railway of the Lower Inn Valley Route in Austria, an evaluation study was conducted by an interview survey (n=1003). The data of this survey included answers on annoyance caused by railroad, road traffic noise and total annoyance as well as self-evaluated noise sensitivity. RESULTS: When annoyance is only related to one of these sources, a 10% share of highly annoyed persons was observed at 59 dB for road noise and 60 dB for railroad noise. The annoyance model including both noise sources with a coefficient of 0.145 for road noise, 0.034 for railroad noise and 0.431 for noise sensitivity (all p-values < 0.01) showed a regression coefficient R2 of 0.299. The presence of road background noise did not influence the annoyance on railway noise. CONCLUSION: The combined influence of road and railway noise showed an increase of total annoyance.

Effects of Motorcycle Noise on Annoyance-A Cross-Sectional Study in the Alps.

Motorcycle noise is an increasing noise problem, especially in Alpine valleys with winding roads and low environmental noise. The annoyance response to motorcycle engine noise is extraordinarily high in comparison to other traffic noise and cannot be explained by standard noise assessment curves. Therefore, the Tyrolean state government decided to initiate a multi-purpose study. Exposures were calculated based on sound-measurements taken across the entire district of Reutte in the western part of the State of Tyrol and a telephone survey (n = 545) was conducted with regional participants. The influence of demographic characteristics; sensitivity to noise; attitudes towards motorcycles and background noise on the annoyance was examined using bivariate analyses. In addition; exposure-response curves and their 95% confidence intervals with cut-off points of 60% and 72% for "highly annoyed" were created. The exposure annoyance response curves for motorcycle noise show a shift of more than 30 dB in annoyance reaction compared to other road traffic noise. The annoyance response to motorcycle noise in this Alpine region is concentrated on summer Sundays and Saturdays and is independent of the background exposure caused by other road traffic.

Combined Effects of Aircraft, Rail, and Road Traffic Noise on Total Noise Annoyance-A Cross-Sectional Study in Innsbruck.

Noise legislation in Austria does not provide an assessment of the cumulative effect of noise from different sources. The desire of citizens for a total noise assessment is getting stronger. Within the pilot project "Gesamtlärmbetrachtung" (Total Noise Investigation) Innsbruck, data from 1031 face-to-face interviews were correlated with exposure data from road, rail and air traffic noise. The interviews were selected in clusters according to the exposure combinations of these three sources. In addition to exposure-response relationships, it has also been found that the annoyance response to air and rail traffic noise is independent of the background noise from road traffic. The total noise annoyance response shows a cumulative effect in each source considered. From the source specific exposure-response relationships, a total noise assessment model based on the annoyance equivalents model was developed. This model is more suitable than the dominant source model and thus also considerable for legal application.

Adhesion, forces and the stability of interfaces.

Weak molecular interactions (WMI) are responsible for processes such as physisorption; they are essential for the structure and stability of interfaces, and for bulk properties of liquids and molecular crystals. The dispersion interaction is one of the four basic interactions types - electrostatics, induction, dispersion and exchange repulsion - of which all WMIs are composed. The fact that each class of basic interactions covers a wide range explains the large variety of WMIs. To some of them, special names are assigned, such as hydrogen bonding or hydrophobic interactions. In chemistry, these WMIs are frequently used as if they were basic interaction types. For a long time, dispersion was largely ignored in chemistry, attractive intermolecular interactions were nearly exclusively attributed to electrostatic interactions. We discuss the importance of dispersion interactions for the stabilization in systems that are traditionally explained in terms of the "special interactions" mentioned above. System stabilization can be explained by using interaction energies, or by attractive forces between the interacting subsystems; in the case of stabilizing WMIs, one frequently speaks of adhesion energies and adhesive forces. We show that the description of system stability using maximum adhesive forces and the description using adhesion energies are not equivalent. The systems discussed are polyaromatic molecules adsorbed to graphene and carbon nanotubes; dimers of alcohols and amines; cellulose crystals; and alcohols adsorbed onto cellulose surfaces.

Impact of uncertainties related to noise indicator determination on observed exposure-effect relationship.

CONTEXT: Noise indicators are the basis to describe noise exposure-effect relationships. The assessment of these noise indicators in field studies includes various uncertainties, so that the true values differ from the determined values used for establishing curve fits. If the relationship between a noise indicator and its effect is nonlinear, uncertainties of the noise indicator modify the observed exposure-effect relationships. MATERIALS AND METHODS: The determination of an exposure-relationship curve fit within a field study was simulated based on the assumption of a given true exposure-relationship without uncertainties and normal distributed uncertainties for the observed noise indicator used for the statistics. RESULTS: In case of an upward curvature of the exposure-effect relationship, the uncertainty for the noise indicator value leads to an asymmetric effect for the curve fit. Uncertainties of the same amount of over- or underestimation will not result in an identical over- or underestimation of the observed effect. A simulation of this effect shows an increased curvature of the observed curve fit, with overestimated exposure-effect relationships. CONCLUSION: Although linear exposure-effect curves are not observed with a systematic shift, quadratic, cubic, and exponential curve forms include a systematic uncertainty in the presented exposure-response curve. If such curves are used to define threshold levels to limit harmful effects of noise, no further uncertainty margins are needed for those situations where the calculated noise indicator uncertainties are equal or lower than those present in the underlying field study.

Mapping few-femtosecond slices of ultra-relativistic electron bunches.

Free-electron lasers are unique sources of intense and ultra-short x-ray pulses that led to major scientific breakthroughs across disciplines from matter to materials and life sciences. The essential element of these devices are micrometer-sized electron bunches with high peak currents, low energy spread, and low emittance. Advanced FEL concepts such as seeded amplifiers rely on the capability of analyzing and controlling the electron beam properties with few-femtosecond time resolution. One major challenge is to extract tomographic slice parameters instead of projected electron beam properties. Here, we demonstrate that a radio-frequency deflector in combination with a dipole spectrometer not only allows for single-shot extraction of a seeded FEL pulse profile, but also provides information on the electron slice emittance and energy spread. The seeded FEL power profile can be directly related to the derived slice emittance as a function of intra-bunch coordinate with a resolution down to a few femtoseconds.

Free-electron laser multiplex driven by a superconducting linear accelerator.

Free-electron lasers (FELs) generate femtosecond XUV and X-ray pulses at peak powers in the gigawatt range. The FEL user facility FLASH at DESY (Hamburg, Germany) is driven by a superconducting linear accelerator with up to 8000 pulses per second. Since 2014, two parallel undulator beamlines, FLASH1 and FLASH2, have been in operation. In addition to the main undulator, the FLASH1 beamline is equipped with an undulator section, sFLASH, dedicated to research and development of fully coherent extreme ultraviolet photon pulses using external seed lasers. In this contribution, the first simultaneous lasing of the three FELs at 13.4 nm, 20 nm and 38.8 nm is presented.