[en] The ATLAS Tile Calorimeter (TileCal) is the central part of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. The readout is segmented into nearly 10000 channels that are calibrated by means of Cesium source, laser, charge injection, and integratorbased systems. The data quality (DQ) relies on extensive monitoring of both collision and calibration data. Automated checks are performed on a set of pre-defined histograms and results are summarized in dedicated web pages. A set of tools is then used by the operators for further inspection of the acquired data with the goal of spotting the origins of problems or other irregularities. Consequently, the TileCal conditions data (calibration constants, channel statuses etc) are updated in databases that are used for the data-reprocessing, or serve as an important input for the maintenance works during the shutdown periods. This talk reviews the software tools used for the DQ monitoring with emphasis on recent developments aiming to integrate all tools into a single platform.

[en] DC high voltage GaAs photoguns are key components at accelerator facilities worldwide. New experiments and new accelerator facilities demand improved performance from these guns, in particular higher current operation and longer photocathode operating lifetime. This conference submission explores bulk GaAs photocathode lifetime as a function of beam current, active photocathode area, laser spot size and the vacuum of the gun and beam line. Lifetime measurements were made at 100 microamps, a beam current relevant for accelerators like CEBAF, and at beam currents of 1 milliamps and 5 milliamps, a regime that is interesting for high current Free Electron Laser (FEL) and Energy Recovery Linac (ERL) operation

[en] The transient degradation of semiconductor device performance under irradiation has long been an issue of concern. A single high-energy charged particle can degrade or permanently destroy the microelectronic component, potentially altering the course or function of the systems. Disruption of the the crystalline structure through the introduction of quasi-stable defect structures can change properties from semiconductor to conductor. Typically, the initial defect formation phase is followed by a recovery phase in which defect-defect or defect-dopant interactions modify the characteristics of the damaged structure. In this LDRD Express, in-situ ion irradiation transmission microscopy (TEM) in-situ TEM experiments combined with atomistic simulations have been conducted to determine the feasibility of imaging and characterizing the defect structure resulting from a single cascade in silicon. In-situ TEM experiments have been conducted to demonstrate that a single ion strike can be observed in Si thin films with nanometer resolution in real time using the in-situ ion irradiation transmission electron microscope (I"3TEM). Parallel to this experimental effort, ion implantation has been numerically simulated using Molecular Dynamics (MD). This numerical framework provides detailed predictions of the damage and follow the evolution of the damage during the first nanoseconds. The experimental results demonstrate that single ion strike can be observed in prototypical semiconductors.

[en] Nearly monodisperse, well crystalline, superparamagnetic CoFe₂O₄ nanoparticles with diameter of 6 nm were synthesized in oleic acid–water–pentanol system at 180 °C. Hydrothermal procedure, as an efficient and environment friendly alternative to organic decomposition methods, was investigated by variation of reaction conditions, and the particle formation mechanism was finally proposed (i.e., hydrolysis of metal oleates in organic phase, with size of the particles (5–8 nm) controlled by polarity-driven precipitation into water phase). As-prepared particles were hydrophobic due to coating by oleic acid. Further modification with dimercaptosuccinic acid led to water-dispersible particles with hydrodynamic diameter of 20 nm. Prepared particles were investigated by TEM, XRD, ICP-AES, light scattering, SQUID magnetometry, and Mössbauer spectroscopy.

[en] The Late Glacial sedimentary sequence of the Stará Jímka paleolake (Bohemian Forest, Czech Republic) is characterized by the prevalence of detrital minerals with an elevated proportion of organic matter and abundant diatom valves in relatively warm periods. The mineral debris originated mainly from local migmatites and mica-schists (or glacial and deluvial deposits derived from the same material). Low background contents of CaO (< 0.20 wt%) and Na₂O (< 0.50 wt%) reflect chemical weathering. Correlation analysis of trace elements shows that the mineral debris concentrates Rb, Cs, Ga, Cr, Zr, Hf, light rare earth elements, Th, U, Pb, Ba, Sr and weakly Zn, whereas Mo, Co, Se, As, Ni, Cu, Br and weakly Au are allocated predominantly to sulphides and organic matter. The sequence contains a continuous horizon with the Laacher See Tephra (LST), causing contrasting maxima of Na, Ca, Cl and Nb in bulk composition. While the phonolitic tephra corresponds to the lower part of the middle LST unit it also contains phosphorus-rich relicts of older sediments with small euhedral (air-transported) volcanic crystals. Such sediments may have occurred in depressions at an older volcano prior to the major Laacher See eruption (~ 12,880 cal. BP).

[en] Materials designed for nuclear reactors undergo microstructural changes resulting from a combination of several environmental factors, including neutron irradiation damage, gas accumulation and elevated temperatures. Typical ion beam irradiation experiments designed for simulating a neutron irradiation environment involve irradiating the sample with a single ion beam and subsequent characterization of the resulting microstructure, often by transmission electron microscopy (TEM). This method does not allow for examination of microstructural effects due to simultaneous gas accumulation and displacement cascade damage, which occurs in a reactor. Sandia’s in situ ion irradiation TEM (I³TEM) offers the unique ability to observe microstructural changes due to irradiation damage caused by concurrent multi-beam ion irradiation in real time. This allows for time-dependent microstructure analysis. A plethora of additional in situ stages can be coupled with these experiments, e.g., for more accurately simulating defect kinetics at elevated reactor temperatures. As a result, this work outlines experiments showing synergistic effects in Au using in situ ion irradiation with various combinations of helium, deuterium and Au ions, as well as some initial work on materials utilized in tritium-producing burnable absorber rods (TPBARs): zirconium alloys and LiAlO₂.

[en] In the Czech Hydrometeorological Institute (CHMI) there exists a unique set of meteorological measurements consisting of the values of vertical atmospheric levels of beta and gamma radiation. In this paper a stochastic data-driven model based on nonlinear regression and on nonhomogeneous Poisson process is suggested. In the first part of the paper, growth curves were used to establish an appropriate nonlinear regression model. For comparison we considered a nonhomogeneous Poisson process with its intensity based on growth curves. In the second part both approaches were applied to the real data and compared. Computational aspects are briefly discussed as well. The primary goal of this paper is to present an improved understanding of the distribution of environmental radiation as obtained from the measurements of the vertical radioactivity profiles by the radioactivity sonde system. - Highlights: → We model vertical atmospheric levels of beta and gamma radiation. → We suggest appropriate nonlinear regression model based on growth curves. → We compare nonlinear regression modelling with Poisson process based modeling. → We apply both models to the real data.

[en] In this paper, Fe₅₀Se₅₀ alloy powders were synthesized from pure elemental powder by mechanical allowing. The structure, microstructure, morphology, chemical composition and thermal behavior at a function of milling times (0–39 h) were investigated by X-ray diffraction (XRD), scanning electron microscopy attached with energy-dispersive spectroscopy and differential scanning calorimetry (DSC). In addition, the interaction hyperfine and magnetic proprieties was examined by transmission Mössbauer spectroscopy (TMS) and thermomagnetic measurements (VSM) respectively. For milling times up to 6 h, the results of refinement of the X-ray diffraction pattern by MAUD software reveal the formation of the β-FeSe hexagonal, amorphous selenium and nanocrystalline α-Fe. The DSC curves show several exothermic and endothermic peaks associated with various phases’ transitions such as the exothermic peak at 103 °C related to crystallization amorphous selenium. However, after prolonging the milling time to 39 h, the XRD shows the formation of α-FeSe phase tetragonal which has plenty of technological interests especially the superconductivity. The Mössbauer spectroscopy confirmed the formation the two-phase paramagnetic hexagonal β-FeSe and α-FeSe tetragonal, according to the XRD and DSC. Measurement of magnetization (VSM) displays that saturation magnetization (MS) decreases as the milling time increases.

[en] We report on magnetic properties of CoFe₂O₄ nano-agglomerates obtained by micro-emulsion technique under specific conditions. The samples form a unique morphology as observed by transmission electron microscopy and scanning electron microscopy investigations. Concerning magnetic properties, they exhibit a considerable coercivity of almost 1 T at 2 K, which continuously decreases up to the characteristic temperature, T_g=350K. The temperature dependence of the zero-field cooled (ZFC) and field cooled (FC) magnetization, respectively, is furcated at the T_g, and the temperature dependencies of the a.c. susceptibility exhibit a frequency-dependent maximum at ∼T_g. The observed behavior is discussed in terms of the super-spin-glass (SSG) and the super-ferromagnetic (SFM) regime considering the morphology of the nano-agglomerates.

[en] This article presents preparation and characterization of zinc, copper and cadmium chromites nanocrystals embedded in a silica matrix. The ZnCr₂O₄/SiO₂, CuCr₂O₄/SiO₂ and CdCr₂O₄/SiO₂ samples were prepared by a conventional sol-gel method using HNO₃ as an acid catalyst, formamide as a modifier, methanol as a solvent and TEOS. Final heat treatment of the nanocomposites was carried out at temperatures in the range of 900 - 1100 deg. C. The resulting samples were characterized by X-ray diffraction, High Resolution Transmission Electron Microscopy, and magnetic measurements.