Experimental analysis of the thermal energy storage potential of a phase change material embedded in additively manufactured lattice structures

Recent literature introduced novel additively manufactured porous metallic structures designed to deliver enhancement of the thermal conductivity of organic phase change materials. Among these, so-called lattice structures are of particular interest for application in lightweight components. Originally investigated for their attractive mass-specific mechanical properties, these geometries were recently proposed, in alternative to metallic foams, as a conductive matrix of phase change materials. However, the geometrical parameters of a lattice structure differ from the ones of a metallic foam and no established data exist in the literature about the influence of the lattice cell geometry on the transient heat transfer enhancement of a phase change material. This work presents an experimental comparison of the thermal behaviour of a composite based on an n-Octadecane paraffin wax embedded in four different aluminium lattices with varying unit cell topology (f2ccz, bcc, bccz, f2bcc), but showing the same cell size, aspect ratio and strut diameter. It is noticed that the unit cell topology affects the transient thermal behaviour beyond its direct effect on the cell porosity. To address this, a specific thermal performance parameter is identified. The sample based on the f2ccz topology represents the best candidate. The influence of orientation with respect to gravity on the heat transfer is also investigated. While the samples show relatively low porosity, ranging from 70.7% to 83.4%, the wide pore diameters lead to a high impact of melt convection on the thermal behaviour of most samples. Up to 28% wall temperature variation is evidenced for different heating orientations

Updates of the ATLAS Tracking Event Data Model (Release 13)

In a previous document we have presented the ATLAS tracking Event Data Model (EDM) that has been developed during the recent restructuring of the ATLAS offline track reconstruction. The tracking EDM has become a cornerstone of the new modular track reconstruction algorithms of both tracking devices of the ATLAS detector, the Inner Detector and the Muon System. Recently, some components have undergone yet another design evolution targeted at completing missing modules and at establishing anticipated functionality for the startup of the ATLAS experiment. One particular aspect of the EDM is that is does not only have to fulfill the requirements of today's algorithmic modules, but has to provide the flexibility for future developments. This document is based on ATLAS software release 13.0.0

ATLAS Detector Paper Back-Up Note: Electrons and Photons

This is the supporting note to the ATLAS Detector paper for electron and photon reconstruction with the Inner Detector. It describes the software used to produce the results presented in the ATLAS Detector paper

THE TOOLS AND MONTE CARLO WORKING GROUP Summary Report from the Les Houches 2009 Workshop on TeV Colliders

This is the summary and introduction to the proceedings contributions for the Les Houches 2009 "Tools and Monte Carlo" working group.Comment: 144 Pages. Workshop site http://wwwlapp.in2p3.fr/conferences/LesHouches/Houches2009/ . Conveners were Butterworth, Maltoni, Moortgat, Richardson, Schumann and Skand

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV