331 research outputs found
New results on focusing of gamma-rays with Laue lenses
We report on new results on the development activity of broad band Laue
lenses for hard X-/gamma-ray astronomy (70/100-600 keV). After the development
of a first prototype, whose performance was presented at the SPIE conference on
Astronomical Telescopes held last year in Marseille (Frontera et al. 2008), we
have improved the lens assembling technology. We present the development status
of the new lens prototype that is on the way to be assembled.Comment: 8 pages, 11 figures, to be Published in SPIE Proceedings,
vol.7437-19, 200
A Laser Based Instrument for MWPC Wire Tension Measurement
A fast and simple method for the measurement of the mechanical tension of wires of Multi Wires Proportional Chambers (MWPCs) is described. The system is based on commercial components and does not require any electrical connection to the wires or electric or magnetic field. It has been developed for the quality control of MWPCs of the Muon Detector of the LHCb experiment in construction at CERN. The system allows a measurement of the wire tension with a precision better than 0.5% within 3-4 seconds per wir
Fast Seismic Vulnerability Evaluation of Historical Masonry Aggregates through Local Analyses: an Adaptive NURBS-based Limit Analysis Approach
An efficient computational tool for the local failures analysis in historical masonry
aggregates is proposed. A NURBS (Non-Uniform Rational B-Spline) representation of
geometry is adopted. NURBS entities, which are common in commercial CAD packages, have
the great advantage to describe complex geometries (such as curved elements and walls with a
high number of holes) with very few elements. An upper bound limit analysis formulation is
implemented, in which the adopted NURBS elements are idealized as rigid bodies with
dissipation allowed only along interfaces. The mesh of NURBS elements is progressively
adjusted through a genetic algorithm in order to minimize the live load multiplier. This
procedure is applied in the evaluation of the horizontal load multiplier associated with the
activation of local mechanisms during a seismic event. Some case studies, referring to masonry
aggregates located in the historical centers of Arsita (Abruzzo region, Italy) and Sora (Lazio
region, Italy), are here presented. A quick evaluation of the seismic vulnerability is performed
through the presented NURBS-based computational tool, showing the high importance of the
local response in the study of the seismic behavior of masonry aggregates
A Cylindrical GEM Inner Tracker for the BESIII experiment at IHEP
The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector
that collects data provided by the collision in the Beijing Electron Positron
Collider II (BEPCII), hosted at the Institute of High Energy Physics of
Beijing. Since the beginning of its operation, BESIII has collected the world
largest sample of J/{\psi} and {\psi}(2s). Due to the increase of the
luminosity up to its nominal value of 10^33 cm-2 s-1 and aging effect, the MDC
decreases its efficiency in the first layers up to 35% with respect to the
value in 2014. Since BESIII has to take data up to 2022 with the chance to
continue up to 2027, the Italian collaboration proposed to replace the inner
part of the MDC with three independent layers of Cylindrical triple-GEM (CGEM).
The CGEM-IT project will deploy several new features and innovation with
respect the other current GEM based detector: the {\mu}TPC and analog readout,
with time and charge measurements will allow to reach the 130 {\mu}m spatial
resolution in 1 T magnetic field requested by the BESIII collaboration. In this
proceeding, an update of the status of the project will be presented, with a
particular focus on the results with planar and cylindrical prototypes with
test beams data. These results are beyond the state of the art for GEM
technology in magnetic field
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