Tracking systems for modern particle physics experiments, both for the search of extremely rare processes, which require high momentum resolutions in ranges dominated by multiple scattering, and for ...the next generation of high luminosity lepton colliders, which require large active volumes and high granularity, make use of light drift chambers able to withstand high rates and, therefore, made of large numbers of closely spaced wires. For such chambers, the use of the classical feed-through technique, as wire anchoring system, cannot be implemented and it is necessary to develop an automatic system (wiring robot) to locate the wires with high accuracy and under a well monitored and uniform mechanical tension with fast and reliable operations.
The Cherenkov light flashes produced by extensive air showers are very short in time. A high bandwidth and fast digitizing readout, therefore, can minimize the influence of the background from the ...light of the night sky, and improve the performance in Cherenkov telescopes. The time structure of the Cherenkov image can further be used in single-dish Cherenkov telescopes as an additional parameter to reduce the background from unwanted hadronic showers. A description of an analysis method which makes use of the time information and the subsequent improvement on the performance of the MAGIC telescope (especially after the upgrade with an ultra fast 2 GSamples/s digitization system in February 2007) will be presented. The use of timing information in the analysis of the new MAGIC data reduces the background by a factor two, which in turn results in an enhancement of about a factor 1.4 of the flux sensitivity to point-like sources, as tested on observations of the Crab Nebula.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Goethite (α-FeOOH) nanorods have been synthesized using two different methods, by aging at different temperatures of ferrihydrite suspensions obtained through co-precipitation, or by fast conversion ...of ferrihydrite through ultrasonic irradiation. The synthesis method and parameters influenced the size and shape of nanoparticles. Stable colloidal suspensions of nanorods have been prepared by purification of the precipitates and subsequent dispersion in deionised water by sonication. The synthesized nanopowders have been characterized by Powder X-ray Diffraction and Scanning Electron Microscopy and the colloidal suspensions by Dynamic Light Scattering and
ζ
-potential measurements. The magnetic field at nuclei level has been investigated by Mössbauer spectroscopy. Moreover, since a colloidal suspension of goethite is a mineral liquid crystal and due to its peculiar magnetic properties, polarized radiation transmittance of colloids in the UV-vis-NIR range has been determined under different magnetic field directions and intensities. It has been found that the transmittance in the NIR range can be tuned by changing magnetic field direction and strength.
Goethite (α-FeOOH) nanorods were synthesized and their size and shape were controlled by synthesis parameters. Stable colloidal suspensions were prepared and their transmittance in NIR range was tuned by modifying magnetic field direction and strength.
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IJS, KILJ, NUK, UL, UM, UPUK
Obesity-related hypertension is associated with increased activity of the renin-angiotensin-aldosterone system (RAAS), increasing arterial stiffness. Aerobic exercise decreases pulse wave velocity ...(PWV), therefore a treatment option for hypertension and obesity. Assess RAAS activity and PWV before and after 4 weeks of aerobic training in unmedicated, pre-to-stage-1 hypertensives. Ten obese subjects (52±3.2 years, body mass index=33.5±1.4) performed 30 min of aerobic exercise on a treadmill 3 days per week at 65% of peak oxygen consumption (VO2peak). Descriptive characteristics, systolic and diastolic blood pressure (SBP and DBP), PWV, and a blood draw was performed at baseline, following the 4-week control and training interventions. No differences in descriptive characteristics during the control period were observed, however, a significant decrease in plasma aldosterone (ALDO) (255.4±75 to 215.8±66 pg ml(-1), P=0.001), SBP (140±12 to 136±10.4 mm Hg; P=0.02), DBP (89±4.2 to 85±6.3 mm Hg; P=0.03) and central PWV (11.2±0.6 to 9.8±0.8 m s(-1); P=0.04) was shown pre-to-post exercise training. Four weeks of moderate-intensity aerobic training in obese, hypertensives decreases plasma ALDO independently of body weight and is significantly correlated to decreases in PWV reductions.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The MAGIC collaboration has studied the high-frequency-peaked BL Lac object 1ES 1218+30.4, at a redshift z = 0.182, using the MAGIC imaging air Cerenkov telescope located on the Canary Island of La ...Palma. A gamma-ray signal was observed with 6.4 s significance. The differential energy spectrum for an energy threshold of 120 GeV can be fitted by a simple power law, yielding F sub(E)(E) = (8.1 c 2.1) x 10 super(-7) E/(250 GeV) super(-3.0c0.4) TeV super(-1) m super(-2) s super(-1). During the 6 days of observation in 2005 January, no time variability on timescales of days was found within the statistical errors. The observed integral flux above 350 GeV is nearly a factor of 2 below the upper limit reported by the Whipple collaboration in 2003.
During its first data cycle, between 2005 and the beginning of 2006, the fast repositioning system of the MAGIC telescope allowed the observation of nine different gamma-ray bursts as possible ...sources of very high energy gamma -rays. These observations were triggered by alerts from Swift, HETE-2, and INTEGRAL; they started as quickly as possible after the alerts and lasted for several minutes, with an energy threshold varying between 80 and 200 GeV, depending on the zenith angle of the burst. No evidence for gamma signals was found, and upper limits for the flux were derived for all events using the standard analysis chain of MAGIC. For the bursts with measured redshifts, the upper limits are compatible with a power-law extrapolation, when the intrinsic fluxes are evaluated taking into account the attenuation due to the scattering in the metagalactic radiation field.
The MAGIC Cerenkov telescope has observed very high energy (VHE) g-ray emission from the active galactic nucleus 1ES 1959+650 during 6 hr in 2004 September and October. The observations were carried ...out alternating with observations of the Crab Nebula, whose data were used as a reference source for optimizing g -ray/hadron separation and for flux comparison. The data analysis shows VHE g-ray emission of 1ES 1959+650 with 68 s significance, at a time of low activity in both optical and X-ray wavelengths. An integral flux above 6180 GeV of about 20% that of the Crab Nebula was obtained. The light curve, sampled over 7 days, shows no significant variations. The differential energy spectrum between 180 GeV and 2 TeV can be fitted with a power-law of index -2.72 c 0.14. The spectrum is consistent with the slightly steeper spectrum seen by HEGRA at higher energies, also during periods of low X-ray activity.
Concentrating Solar Power (CSP) is considered to be one of the most promising and sustainable technologies for electricity production in the future, and as efficiency of solar thermal systems rapidly ...increases with increasing working temperature, the big challenge for future is to develop novel solutions for solar receivers. In this framework, Ultra-High Temperature Ceramics (UHTCs) are mainly studied as thermal protection materials for aerospace and military applications, but their peculiar properties (very high melting points and good thermo-mechanical properties at high temperatures) can be advantageously exploited to increase the operating temperature of thermodynamic solar plants in concentrating solar power systems. This work is devoted to the study and characterization of the spectral reflectance of hafnium and zirconium diborides containing MoSi2 as secondary phase in order to evaluate their potential as novel solar absorbers. To assess the spectral selectivity properties, room-temperature hemispherical reflectance spectra were measured from the UV wavelength region to the mid-infrared, considering different levels of porosity for each system, in order to understand how porosity affect spectral reflectance. Moreover, for zirconium diboride and hafnium diboride composites containing 10vol% of MoSi2 sintering aid, the thermal emittance was measured in the 1100–1400K temperature range in PROMES-CNRS solar furnace. Data obtained were compared with spectral characteristics and high temperature emittance of a monolithic silicon carbide.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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