Impacts of misalignment effects on the Muon Spectrometer Performance

The ATLAS detector, currently being installed at CERN, is designed to exploit the full potential of the LHC, identifying and providing highly accurate energy and momentum measurements of particles emerging from the LHC protonproton collisions with a centre-of-mass energy at 14 TeV, starting in 2007. High-momentum final-state muons are among the most promising signatures at the LHC, thanks to a high-resolution Muon Spectrometer with standalone triggering and momentum measurement. As well known, muons interact primarily trough their electromagnetic charge, but since they are 200 times more massive than the electrons they are less affected by the electric fields of the nuclei they encounter. Muons with an energy of more than a few GeV penetrate the calorimeter and can reach the Muon Spectrometer, which consists out of more than 1.200 single drift-tubes chambers. The correct alignment of the ATLAS Muon Spectrometer is crucial to ensure its design performance. This note documents the first attempt at using various misaligned Muonspectrometer layouts to study their impacts Muon Spectrometer performance

A real delivery problem dealt with Monte Carlo techniques

[EN] In this paper we use Monte Carlo Techniques to deal with a real world delivery problem of a food company in Valencia (Spain). The problem is modeled as a set of 11 instances of the well known Vehicle Routing Problem, VRP, with additional time constraints. Given that VRP is a NP-hard problem, a heuristic algorithm, based on Monte Carlo techniques, is implemented. The solution proposed by this heuristic algorithm reaches distance and money savings of about 20% and 5% respectively.This research was partially supported by MICINN, Project MTM2013-43540-P and by UPV, Project Programa de Apoyo a la Investigación y Desarrollo de la UPV PAID-06-12.S577181Fernández de Córdoba, P., L.M. García-Raffi and J.M. Sanchis Llopis (1998), A heuristic algorithm based on Monte Carlo methods for the Rural Postman Problem.Computers and Op. Research,25, No. 12, pp. 1097–1106, 1998.Fernández de Córdoba, P. and L.M. García-Raffi, E. Nieto and J.M. Sanchis Llopis (1999a), Aplicación de técnicas Monte Carlo a un problema real de Rutas de Vehículos.Anales de Ingeniería, Colombia. In press.Fernández de Córdoba, P., L.M. García-Raffi and J.M. Sanchis Llopis (1999b), A Constructive Parallel Algorithm based on Monte Carlo techniques for Routing Problems, Submitted toParallel Computers.Laporte, G. (1992), The Vehicle Routing Problem: an overview of exact and approximate algorithms,European Journal of Operations Research,59, 345.Laporte, G., M. Desrochers and Y. Nobert (1985), “Optimal Routing under Capacity and Distance Restrictions.Operations Research,33, pp. 1050–1073.Laporte G. and Y. Nobert (1987), Exact algorithms for The Vehicle Routing Problem,Surveys in Combinatorial Optimization (S. Martello, G. Laporte, M. Minoux and C. Ribeiro Eds.). North-HollandAmsterdamMayado, A. (1998), Organización de los itinerarios de la flota de camiones de reparto de una sociedad cooperativa. Optimización mediante técnicas de simulación Monte Carlo. Proyecto Fin de Carrera. E.T.S.I.I. Universidad Politécnica de Valencia

Consideration of Collision "Consequence" in Satellite Conjunction Assessment and Risk Analysis

Classic risk management theory requires the assessment of both likelihood and consequence of deleterious events. Satellite conjunction risk assessment has produced a highly-developed theory for assessing collision likelihood but holds a completely static solution for collision consequence, treating all potential collisions as essentially equally worrisome. This may be true for the survival of the protected asset, but the amount of debris produced by the potential collision, and therefore the degree to which the orbital corridor may be compromised, can vary greatly among satellite conjunctions. This study leverages present work on satellite collision modeling to develop a method by which it can be estimated, to a particular confidence level, whether a particular collision is likely to produce a relatively large or relatively small amount of resultant debris and how this datum might alter conjunction remediation decisions. The more general question of orbital corridor protection is also addressed, and a preliminary framework presented by which both collision likelihood and consequence can be jointly considered in the risk assessment process

SST-GATE: A dual mirror telescope for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) will be the world's first open observatory for very high energy gamma-rays. Around a hundred telescopes of different sizes will be used to detect the Cherenkov light that results from gamma-ray induced air showers in the atmosphere. Amongst them, a large number of Small Size Telescopes (SST), with a diameter of about 4 m, will assure an unprecedented coverage of the high energy end of the electromagnetic spectrum (above ~1TeV to beyond 100 TeV) and will open up a new window on the non-thermal sky. Several concepts for the SST design are currently being investigated with the aim of combining a large field of view (~9 degrees) with a good resolution of the shower images, as well as minimizing costs. These include a Davies-Cotton configuration with a Geiger-mode avalanche photodiode (GAPD) based camera, as pioneered by FACT, and a novel and as yet untested design based on the Schwarzschild-Couder configuration, which uses a secondary mirror to reduce the plate-scale and to allow for a wide field of view with a light-weight camera, e.g. using GAPDs or multi-anode photomultipliers. One objective of the GATE (Gamma-ray Telescope Elements) programme is to build one of the first Schwarzschild-Couder prototypes and to evaluate its performance. The construction of the SST-GATE prototype on the campus of the Paris Observatory in Meudon is under way. We report on the current status of the project and provide details of the opto-mechanical design of the prototype, the development of its control software, and simulations of its expected performance.Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223

The ALMA Frontier Fields Survey - IV. Lensing-corrected 1.1 mm number counts in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223

[abridged] Characterizing the number counts of faint, dusty star-forming galaxies is currently a challenge even for deep, high-resolution observations in the FIR-to-mm regime. They are predicted to account for approximately half of the total extragalactic background light at those wavelengths. Searching for dusty star-forming galaxies behind massive galaxy clusters benefits from strong lensing, enhancing their measured emission while increasing spatial resolution. Derived number counts depend, however, on mass reconstruction models that properly constrain these clusters. We estimate the 1.1 mm number counts along the line of sight of three galaxy clusters, i.e. Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223, which are part of the ALMA Frontier Fields Survey. We perform detailed simulations to correct these counts for lensing effects. We use several publicly available lensing models for the galaxy clusters to derive the intrinsic flux densities of our sources. We perform Monte Carlo simulations of the number counts for a detailed treatment of the uncertainties in the magnifications and adopted source redshifts. We find an overall agreement among the number counts derived for the different lens models, despite their systematic variations regarding source magnifications and effective areas. Our number counts span ~2.5 dex in demagnified flux density, from several mJy down to tens of uJy. Our number counts are consistent with recent estimates from deep ALMA observations at a 3$\sigma$ level. Below $\approx$ 0.1 mJy, however, our cumulative counts are lower by $\approx$ 1 dex, suggesting a flattening in the number counts. In our deepest ALMA mosaic, we estimate number counts for intrinsic flux densities $\approx$ 4 times fainter than the rms level. This highlights the potential of probing the sub-10 uJy population in larger samples of galaxy cluster fields with deeper ALMA observations.Comment: 19 pages, 14 figures, 3 tables. Accepted for publication in A&

Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud

Satellite galaxies are predicted to generate gravitational density wakes as they orbit within the dark matter (DM) halos of their hosts, causing their orbits to decay over time. The recent infall of the Milky Way's (MW) most massive satellite galaxy, the Large Magellanic Cloud (LMC), affords us the unique opportunity to study this process in action. In this work, we present high-resolution ($m_{dm} = 4 \times 10^4 M_{\odot}$ ) N-body simulations of the MW-LMC interaction over the past 2 Gyr. We quantify the impact of the LMC's passage on the density and kinematics of the MW's DM halo and the observability of these structures in the MW's stellar halo. The LMC is found to generate pronounced Local and Global wakes in both the DM and stellar halos, leads to both local overdensities and distinct kinematic patterns that should be observable with ongoing and future surveys. Specifically, the Global Wake will result in redshifted radial velocities of stars in the North and blueshifts in the South, at distances larger than 45 kpc. The Local Wake traces the orbital path of the LMC through the halo (50-200 kpc), resulting in a stellar overdensity with a distinct, tangential kinematic pattern that persists to the present day. The detection of the MW's halo response will constrain: the infall mass of the LMC and its orbital trajectory, the mass of the MW, and it may inform us about the nature of the dark matter particle itself.Comment: 41 pages, 27 figures. Accepted to ApJ. Some terminology was changed. High-resolution images and figures can be found at https://bit.ly/2S25Yz

JPCam: A 1.2Gpixel camera for the J-PAS survey

JPCam is a 14-CCD mosaic camera, using the new e2v 9k-by-9k 10microm-pixel 16-channel detectors, to be deployed on a dedicated 2.55m wide-field telescope at the OAJ (Observatorio Astrofisico de Javalambre) in Aragon, Spain. The camera is designed to perform a Baryon Acoustic Oscillations (BAO) survey of the northern sky. The J-PAS survey strategy will use 54 relatively narrow-band (~13.8nm) filters equi-spaced between 370 and 920nm plus 3 broad-band filters to achieve unprecedented photometric red-shift accuracies for faint galaxies over ~8000 square degrees of sky. The cryostat, detector mosaic and read electronics is being supplied by e2v under contract to J-PAS while the mechanical structure, housing the shutter and filter assembly, is being designed and constructed by a Brazilian consortium led by INPE (Instituto Nacional de Pesquisas Espaciais). Four sets of 14 filters are placed in the ambient environment, just above the dewar window but directly in line with the detectors, leading to a mosaic having ~10mm gaps between each CCD. The massive 500mm aperture shutter is expected to be supplied by the Argelander-Institut fur Astronomie, Bonn. We will present an overview of JPCam, from the filter configuration through to the CCD mosaic camera. A brief outline of the main J-PAS science projects will be included.Comment: 11 pages and 9 figure

A zeta function approach to the relation between the numbers of symmetry planes and axes of a polytope

A derivation of the Ces\`aro-Fedorov relation from the Selberg trace formula on an orbifolded 2-sphere is elaborated and extended to higher dimensions using the known heat-kernel coefficients for manifolds with piecewise-linear boundaries. Several results are obtained that relate the coefficients, $b_i$, in the Shephard-Todd polynomial to the geometry of the fundamental domain. For the 3-sphere we show that $b_4$ is given by the ratio of the volume of the fundamental tetrahedron to its Schl\"afli reciprocal.Comment: Plain TeX, 26 pages (eqn. (86) corrected

Maxwell equations in matrix form, squaring procedure, separating the variables, and structure of electromagnetic solutions

The Riemann -- Silberstein -- Majorana -- Oppenheimer approach to the Maxwell electrodynamics in vacuum is investigated within the matrix formalism. The matrix form of electrodynamics includes three real 4 \times 4 matrices. Within the squaring procedure we construct four formal solutions of the Maxwell equations on the base of scalar Klein -- Fock -- Gordon solutions. The problem of separating physical electromagnetic waves in the linear space \lambda_{0}\Psi^{0}+\lambda_{1}\Psi^{1}+\lambda_{2}\Psi^{2}+ lambda_{3}\Psi^{3} is investigated, several particular cases, plane waves and cylindrical waves, are considered in detail.Comment: 26 pages 16 International Seminar NCPC, May 19-22, 2009, Minsk, Belaru