674 research outputs found
Silicon photomultiplier arrays - a novel photon detector for a high resolution tracker produced at FBK-irst, Italy
A silicon photomultiplier (SiPM) array has been developed at FBK-irst having
32 channels and a dimension of 8.0 x 1.1 mm^2. Each 250 um wide channel is
subdivided into 5 x 22 rectangularly arranged pixels. These sensors are
developed to read out a modular high resolution scintillating fiber tracker.
Key properties like breakdown voltage, gain and photon detection efficiency
(PDE) are found to be homogeneous over all 32 channels of an SiPM array. This
could make scintillating fiber trackers with SiPM array readout a promising
alternative to available tracker technologies, if noise properties and the PDE
are improved
Witten index and phase diagram of compactified N=1 supersymmetric Yang-Mills theory on the lattice
Owing to confinement, the fundamental particles of N=1 Supersymmetric
Yang-Mills (SYM) theory, gluons and gluinos, appear only in colourless bound
states at zero temperature. Compactifying the Euclidean time dimension with
periodic boundary conditions for fermions preserves supersymmetry, and
confinement is predicted to persist independently of the length of the
compactified dimension. This scenario can be tested non-perturbatively with
Monte-Carlo simulations on a lattice. SUSY is, however, broken on the lattice
and can be recovered only in the continuum limit. The partition function of
compactified N=1 SYM theory with periodic fermion boundary conditions
corresponds to the Witten index. Therefore it can be used to test whether
supersymmetry is realized on the lattice. Results of our recent numerical
simulations are presented, supporting the disappearance of the deconfinement
transition in the supersymmetric limit and the restoration of SUSY at low
energies.Comment: 7 pages, 3 figures, Proceedings of the 33rd International Symposium
on Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe International
Conference Center, Kobe, Japa
Phase structure of the N=1 supersymmetric Yang-Mills theory at finite temperature
Supersymmetry (SUSY) has been proposed to be a central concept for the
physics beyond the standard model and for a description of the strong
interactions in the context of the AdS/CFT correspondence. A deeper
understanding of these developments requires the knowledge of the properties of
supersymmetric models at finite temperatures. We present a Monte Carlo
investigation of the finite temperature phase diagram of the N=1 supersymmetric
Yang-Mills theory (SYM) regularised on a space-time lattice. The model is in
many aspects similar to QCD: quark confinement and fermion condensation occur
in the low temperature regime of both theories. A comparison to QCD is
therefore possible. The simulations show that for N=1 SYM the deconfinement
temperature has a mild dependence on the fermion mass. The analysis of the
chiral condensate susceptibility supports the possibility that chiral symmetry
is restored near the deconfinement phase transition.Comment: 26 pages, 12 figure
A Scintillating Fiber Tracker With SiPM Readout
We present a prototype for the first tracking detector consisting of 250
micron thin scintillating fibers and silicon photomultiplier (SiPM) arrays. The
detector has a modular design, each module consists of a mechanical support
structure of 10mm Rohacell foam between two 100 micron thin carbon fiber skins.
Five layers of scintillating fibers are glued to both top and bottom of the
support structure. SiPM arrays with a channel pitch of 250 micron are placed in
front of the fibers. We show the results of the first module prototype using
multiclad fibers of types Bicron BCF-20 and Kuraray SCSF-81M that were read out
by novel 32-channel SiPM arrays from FBK-irst/INFN Perugia as well as
32-channel SiPM arrays produced by Hamamatsu. A spatial resolution of 88 micron
+/- 6 micron at an average yield of 10 detected photons per minimal ionizig
particle has been achieved.Comment: 5 pages, 7 figures, submitted as proceedings to the 11th Topical
Seminar on Innovative Particle and Radiation Detectors (IPRD08
Compactified N=1 supersymmetric Yang-Mills theory on the lattice: Continuity and the disappearance of the deconfinement transition
Fermion boundary conditions play a relevant role in revealing the confinement
mechanism of N=1 supersymmetric Yang-Mills theory with one compactified
space-time dimension. A deconfinement phase transition occurs for a
sufficiently small compactification radius, equivalent to a high temperature in
the thermal theory where antiperiodic fermion boundary conditions are applied.
Periodic fermion boundary conditions, on the other hand, are related to the
Witten index and confinement is expected to persist independently of the length
of the compactified dimension. We study this aspect with lattice Monte Carlo
simulations for different values of the fermion mass parameter that breaks
supersymmetry softly. We find a deconfined region that shrinks when the fermion
mass is lowered. Deconfinement takes place between two confined regions at
large and small compactification radii, that would correspond to low and high
temperatures in the thermal theory. At the smallest fermion masses we find no
indication of a deconfinement transition. These results are a first signal for
the predicted continuity in the compactification of supersymmetric Yang-Mills
theory.Comment: 17 pages, 9 Figure
Charmonia in moving frames
Lattice simulation of charmonium resonances with non-zero momentum provides
additional information on the two-meson scattering matrices. However, the
reduced rotational symmetry in a moving frame renders a number of states with
different in the same lattice irreducible representation. The
identification of for these states is particularly important, since
quarkonium spectra contain a number of states with different in a
relatively narrow energy region. Preliminary results concerning
spin-identification are presented in relation to our study of charmonium
resonances in flight on the Nf=2+1 CLS ensembles.Comment: 6 pages, presented at the 35th International Symposium on Lattice
Field Theory, 18-24 June 2017, Granada, Spai
Propagation of semantic information between orthophoto and 3D replica: a H-BIM system for the north transept of Pisa Cathedral
This contribution proposes a methodological approach for the transfer of annotations between orthophotos and 3D digital heritage models, relying on a mesh-based/point-based representation. The workflow leverages on the exploitation of 2D/3D projective relations and on the identification, propagation, modelling and tiling of virtual models of architectural heritage. Referring to the significant case study of Pisa Cathedral, the method is tested to ensure an informative continuum between 2D medias and 3D representations, in terms of morphology, geometry and semantic enrichment. At first, a high resolution ortho-photo is created to support studies related to conservation and restoration, e.g. to highlight degradation patterns and materials as well as to distinguish cracks, frescoed surfaces, decorations. Then, the information is translated from the 2D support to a virtual 3D mockup: this step is essential to ensure a complete understanding of the architectural heritage object, that can thus be studied in its entirety, considering its morphological complexities. The proposed approach provides a more effective system for the transfer and exchange of semantic information from high-resolution orthophotos to semantically rich 3D models, that can be fundamental even in view of the construction of Heritage-Building Information Modeling (H-BIM) environments
CONNECTING GEOMETRY AND SEMANTICS VIA ARTIFICIAL INTELLIGENCE: FROM 3D CLASSIFICATION OF HERITAGE DATA TO H-BIM REPRESENTATIONS
Cultural heritage information systems, such as H-BIM, are becoming more and more widespread today, thanks to their potential to bring together, around a 3D representation, the wealth of knowledge related to a given object of study. However, the reconstruction of such tools starting from 3D architectural surveying is still largely deemed as a lengthy and time-consuming process, with inherent complexities related to managing and interpreting unstructured and unorganized data derived, e.g., from laser scanning or photogrammetry. Tackling this issue and starting from reality-based surveying, the purpose of this paper is to semi-automatically reconstruct parametric representations for H-BIM-related uses, by means of the most recent 3D data classification techniques that exploit Artificial Intelligence (AI). The presented methodology consists of a first semantic segmentation phase, aiming at the automatic recognition through AI of architectural elements of historic buildings within points clouds; a Random Forest classifier is used for the classification task, evaluating each time the performance of the predictive model. At a second stage, visual programming techniques are applied to the reconstruction of a conceptual mock-up of each detected element and to the subsequent propagation of the 3D information to other objects with similar characteristics. The resulting parametric model can be used for heritage preservation and dissemination purposes, as common practices implemented in modern H-BIM documentation systems. The methodology is tailored to representative case studies related to the typology of the medieval cloister and scattered over the Tuscan territory
- …