Spectral aerosol optical depth from SI-traceable spectral solar irradiance measurements

Spectroradiometric measurements of direct solar irradiance traceable to the SI were performed by three spectroradiometer systems during a 3-week campaign in September 2022 at the Izaña Atmospheric Observatory (IZO) located on the island of Tenerife, Canary Islands, Spain. The spectroradiometers provided direct spectral irradiance measurements in the spectral ranges 300 to 550 nm (QASUME), 550 to 1700 nm (QASUME-IR), 300 to 2150 nm (BiTec Sensor, BTS), and 316 to 1030 nm (Precision Solar Spectroradiometer, PSR), with relative standard uncertainties of 0.7 %, 0.9 %, and 1 % for QASUME/QASUME-IR, the PSR, and the BTS respectively. The calibration of QASUME and QASUME-IR was validated prior to this campaign at Physikalisch-Technische Bundesanstalt (PTB) by measuring the spectral irradiance from two spectral irradiance sources, the high-temperature blackbody BB3200pg as a national primary standard and the tuneable laser facility TULIP

Nuclear Polarization of Molecular Hydrogen Recombined on a Non-metallic Surface

The nuclear polarization of $\mathrm{H}_2$ molecules formed by recombination of nuclear polarized H atoms on the surface of a storage cell initially coated with a silicon-based polymer has been measured by using the longitudinal double-spin asymmetry in deep-inelastic positron-proton scattering. The molecules are found to have a substantial nuclear polarization, which is evidence that initially polarized atoms retain their nuclear polarization when absorbed on this type of surfac

Quark helicity distributions in the nucleon for up, down, and strange quarks from semi--inclusive deep--inelastic scattering

Polarized deep--inelastic scattering data on longitudinally polarized hydrogen and deuterium targets have been used to determine double spin asymmetries of cross sections. Inclusive and semi--inclusive asymmetries for the production of positive and negative pions from hydrogen were obtained in a re--analysis of previously published data. Inclusive and semi--inclusive asymmetries for the production of negative and positive pions and kaons were measured on a polarized deuterium target. The separate helicity densities for the up and down quarks and the anti--up, anti--down, and strange sea quarks were computed from these asymmetries in a ``leading order'' QCD analysis. The polarization of the up--quark is positive and that of the down--quark is negative. All extracted sea quark polarizations are consistent with zero, and the light quark sea helicity densities are flavor symmetric within the experimental uncertainties. First and second moments of the extracted quark helicity densities in the measured range are consistent with fits of inclusive data

Quark fragmentation to π±\pi^{\pm}, π0\pi^{0}, K±K^{\pm}, pp and pˉ\bar{p} in the nuclear environment

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi-inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium, nitrogen and krypton targets. The differential multiplicity for krypton relative to that of deuterium has been measured for the first time for various identified hadrons ($\pi^+$, $\pi^-$, $\pi^0$, $K^+$, $K^-$, $p$ and $\bar{p}$) as a function of the virtual photon energy $\nu$, the fraction $z$ of this energy transferred to the hadron, and the hadron transverse momentum squared $p_t^2$. The multiplicity ratio is strongly reduced in the nuclear medium at low $\nu$ and high $z$, with significant differences among the various hadrons. The distribution of the hadron transverse momentum is broadened towards high $p_t^2$ in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei.Comment: 8 pages, 5 figure

Case Studies on the Thermally Induced Stresses in Insulating Glass Units via Numerical Calculation

In the structural design of facade glazing, various types of loads such as dead weight, wind and climatic loads (pressure differences) must be taken into account. In practice, however, there are many cases of damage that can be attributed to direct solar radiation. In these cases, a so-called thermally induced fracture takes place, which can occur as a result of large in-plane temperature differences within the glass. Due to the increasing complexity of glazing constructions, this load type should be taken into account in future glass design. For this reason, thermal-mechanical investigations, were conducted. Commercially used double and triple insulating glass units were considered as vertical glazing and the solar direct absorptance per glass pane was varied. For numerical calculations, measured temperature data from the German Weather Service and free available Clear Sky model data were used as meteorological input. The results show that solar irradiance, along with temperature, is the driving influence on the thermally induced stress in insulating glass units. The investigations indicate that the inner pane becomes relevant on colder days and the outer pane on warmer days. Results also show, that the level of the outside temperature plays a negligible role for the thermally induced stresses of the middle pane

Deflection of a cladding panel of fully tempered glass in curtain wall system

The article presents a study on the mechanical behavior of facade cladding panel consisting of aluminum frame and fully tempered sheet glass under the action of uniformly distributed load. The study involved tests of full-size samples of two structural solutions of the cladding panel in a curtain wall system for two different geometrical configurations of the panel. Experimental data showed a high similarity with the results of a static calculation in the zone of linear elastic deformation. Therefore, the use of SJ Mepla finite element software package for the calculation of described structures was verified. The influence of the boundary conditions on determination of deflections in numerical model as well as the character of seal deformation was described. The criteria of the loss of bearing capacity of a system was defined. Empirical formulas for calculating the panel deflection for specific geometrical configurations of a panel were proposed

Hochtemperaturfestigkeit von geglühtem Kalk‐Natronsilicatglas

Bei der additiven Fertigung und beim thermischen Vorspannen von Glas ist dessen Festigkeit für den aufgrund des Herstell- bzw. Veredelungsprozesses relevanten Temperaturbereich nur wenig erforscht. Um die Auswirkungen unterschiedlicher Temperaturen auf die Festigkeit des Werkstoffs näher bestimmen zu können, wurde der Doppelringbiegeversuch nach EN 1288-5 mit einer Universalprüfmaschine mit Ofen an Glasplatten von Raumtemperatur bis 550 °C durchgeführt. Vor der Prüfung wurden die Proben kontrolliert vorgeschädigt, gelagert und mit Wärme behandelt. Die Ergebnisse zeigen eine Zunahme der Bruchfestigkeit mit steigender Prüftemperatur. Der kritische Spannungsintensitätsfaktor und die kritische Energiefreisetzungsrate zeigen keine Temperaturabhängigkeit