TREX-DM: a low background Micromegas-based TPC for low-mass WIMP detection

Dark Matter experiments are recently focusing their detection techniques in low-mass WIMPs, which requires the use of light elements and low energy threshold. In this context, we describe the TREX-DM experiment, a low background Micromegas-based TPC for low-mass WIMP detection. Its main goal is the operation of an active detection mass $\sim$0.3 kg, with an energy threshold below 0.4 keVee and fully built with previously selected radiopure materials. This work describes the commissioning of the actual setup situated in a laboratory on surface and the updates needed for a possible physics run at the Canfranc Underground Laboratory (LSC) in 2016. A preliminary background model of TREX-DM is also presented, based on a Geant4 simulation, the simulation of the detector's response and two discrimination methods: a conservative muon/electron and one based on a neutron source. Based on this background model, TREX-DM could be competitive in the search for low-mass WIMPs. In particular it could be sensitive, e.g., to the low-mass WIMP interpretation of the DAMA/LIBRA and other hints in a conservative scenario.Comment: Proceedings of the XIV International Conference on Topics in Astroparticle and Underground Physics (TAUP 2015), 7-11 September 2015, Torino, Ital

Towards the production of 50'000 tonnes of low-carbon steel sheet for the LHC superconducting dipole and quadrupole magnets

A total of 50'000 tonnes of low-carbon steel sheet has been ordered for the LHC main magnets. After three years of production, about 10'000 tonnes of steel sheet have been produced by Cockerill-Sambre Groupe Usinor. This paper gives a summary of the manufacturing process and improvements implemented as well as an overview of the difficulties encountered during this production. Preliminary statistics obtained for the mechanical and magnetic steel properties are presented

Safety training for migrant workers in the construction industry: A systematic review and future research agenda

In the construction sector, there is a high risk for accidents, injuries, and fatalities, particularly for migrant workers who comprise a large proportion of the workforce. This article presents a systematic literature review of current safety training provision for migrant construction workers. In the interests of rigor, we draw on the learning, training transfer, and training effectiveness literatures, exploring not only the extent to which training brings about the intended outcomes, in terms of enhanced safety behaviors, and reduced accidents and injuries, but also the factors that influence learning and transfer of training back to the working environment. The literature search revealed only 18 peer-reviewed articles have been published since 2000, which is particularly surprising, given the disproportionate accident and fatality rates for migrant workers. Consequently, we propose a research agenda to enhance safety training for low skilled, migrant and native construction workers, drawing on cognitive and social constructivist instructional design models, which view training as a dynamic process involving active participation of trainees. We advocate the importance of attending to the situational context in which workers are embedded, including labor market conditions, social relations, and cultural differences. Finally, we propose the need for further longitudinal, multidimensional research to evaluate the impact of safety training on learning, transfer of training, and individual- and organizational-level outcomes, such as behavior change, and accident and fatality rates

Electric field assisted dissolution of metal clusters in metal island films for photonic heterostructures

The dissolution of metal clusters in metal island films by the simultaneous application of electric field and temperature is reported. The consequent fading of surface plasmon resonance greatly modifies the optical properties of the samples. The dissolution process is verified in island films of different metals, obtained under different conditions and covered by different dielectric materials, as well as on multilayer dielectric stacks showing interferential properties. The tailoring possibilities of the optical behavior of metal island films combined with the inexpensive technical requirements of this approach open up the possibility to produce low-cost photonic heterostructures

Production of Low-Carbon Magnetic Steel for the LHC Superconducting Dipole and Quadrupole Magnets

In 1996 CERN negotiated a contract with Cockerill Sambre â ARCELOR Group for the supply of 50 000 tonnes of low-carbon steel for the LHC main magnets: this was the first contract to be placed for the project, and one of the single largest. In 2005 â after nine years of work â the contract is being successfully completed. This paper describes the steel specifically developed, known as MAGNETILâ¢, its manufacturing and quality control process, organization of production, logistics and contract follow-up. Extensive statistics have been collected relating to physical, mechanical and technological parameters. Specific attention is dedicated to magnetic measurements (coercivity and permeability) performed at both room and cryogenic temperatures, the equipment used and statistical results. Reference is also made to the resulting precision of the fineblanked laminations used for the magnet yoke. The technology transfer from the particle accelerator domain to industry is ongoing, for example for the screening of high voltage cables buried in the ground

TREX-DM: a low background Micromegas-based TPC for low mass WIMP detection

Dark Matter experiments are recently focusing their detection techniques in low-mass WIMPs, which requires the use of light elements and low energy threshold. In this context, we present the TREX-DM experiment, a low background Micromegas-based TPC for low-mass WIMP detection. Its main goal is the operation of an active detection mass $\sim$0.300 kg, with an energy threshold below 0.4 keVee and fully built with previously selected radiopure materials. This article describes the actual setup, the first results of the comissioning in Ar+2\%iC$_4$H$_{10}$ at 1.2 bar and the future updates for a possible physics run at the Canfranc Underground Laboratory in 2016. A first background model is also presented, based on Geant4 simulations and a muon/electron discrimination method. In a conservative scenario, TREX-DM could be sensitive to DAMA/LIBRA and other hints of positive WIMPs signals, with some space for improvement with a neutron/electron discrimination method or the use of other light gases.Comment: Proceedings of the 7th Symposium on Large TPCs for Low-Energy Rare Event Detectio

Size quantization of Dirac fermions in graphene constrictions

Quantum point contacts (QPCs) are cornerstones of mesoscopic physics and central building blocks for quantum electronics. Although the Fermi wave-length in high-quality bulk graphene can be tuned up to hundreds of nanometers, the observation of quantum confinement of Dirac electrons in nanostructured graphene systems has proven surprisingly challenging. Here we show ballistic transport and quantized conductance of size-confined Dirac fermions in lithographically-defined graphene constrictions. At high charge carrier densities, the observed conductance agrees excellently with the Landauer theory of ballistic transport without any adjustable parameter. Experimental data and simulations for the evolution of the conductance with magnetic field unambiguously confirm the identification of size quantization in the constriction. Close to the charge neutrality point, bias voltage spectroscopy reveals a renormalized Fermi velocity ($v_F \approx 1.5 \times 10^6 m/s$) in our graphene constrictions. Moreover, at low carrier density transport measurements allow probing the density of localized states at edges, thus offering a unique handle on edge physics in graphene devices.Comment: 24 pages including 20 figures and 1 table. Corrected typos. To appear in Nature Communication

Advancing in the analysis of materials in electr(on)ic equipment

Despite there is a great effort to support strategies for a circular economy of electr(on)ics as maintenance, repair, remanufacture and reuse, recycling keeps being the final ultimate stage reached by them. As the supply of materials has become a key issue for the economic and technology development, more information about the content of materials in electr(on)ics is in order. This is especially for printed circuit boards contained in the majority of electr(on)ics which have a great variety of materials with a significant economic value. This paper discusses two methodologies to quantify the material composition of these parts. The first methodology quantifies the material content using two algorithms to identify the typologies of electr(on)ics components, and the average material composition of some typologies of electr(on)ic components given by original manufacturers. The second methodology uses the Database of SEmiconductors (DoSE) which contains the full material composition of about 250 different electr(on)ic components of printed circuit boards. A case study based on the analysis of two models of battery management systems contained in the batteries of electric vehicles is developed to compare the material composition results obtained from the two methodologies. Although the analysis is limited to some electr(on)ic components, mainly the integrated circuit and capacitors, the results of the composition of the battery management system are given for a list of materials including aluminum, copper, iron, gold, lead, nickel and tantalum. For two of the most economically relevant materials, copper and gold, the results obtained by the two methodologies differ 2% for copper and 4% for gold. To advance towards more automatized and systematic methodologies to estimate the material composition of the battery management systems, there are some further developments needed: to increase datasets for other electr(on)ic components as connectors, and better quantification of the number of layers and finishing of the circuit boards as they are made of significant quantities of copper and gold

Electromagnetic characterization of the 990 ton gapless magnets for the OPERA experiment

The instrumented targets of the OPERA neutrino experiment are complemented by two massive spectrometers based on gapless iron magnets. In 2006, a systematic assessment of their electromagnetic properties have been carried out. In this document, we report the results of such characterization and demonstrate that the achieved performance fulfill the physics requirements for the study of νμ→ντ oscillations