Beam-beam-induced orbit effects at LHC

For high bunch intensities the long-range beam-beam interactions are strong enough to provoke effects on the orbit. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are presented in this paper.Comment: 5 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201

Beyond Standard Model Physics at the Large Hadron Collider at CERN

This conference report presents a compilation of some of the latest results on prospects for Extra Dimensions and Heavy Bosons Models with A Toroidal LHC ApparatuS (ATLAS) and the Compact Muon Solenoide (CMS). ATLAS and CMS are two general purpose detectors placed at two equidistant points in the Large Hadron Collider (LHC) at CERN. The results presented here correspond, in most of the cases, to full simulation and full reconstruction of the hadron interactions at sqrt(s) = 14 TeV and to low and/or high luminosity. In general, theoretical and systematic uncertainties are considered in the final results

Luminosity Optimization and Calibration in the LHC

The ability of a particle collider to produce the required number of events, the luminosity, is usually used to size its performances. As demonstrated in many accelerators optimizing and calibrating the luminosity can be done using the Van Der Meer method which consist of shifting one beam with respect to the other while recording the event rate. In the LHC it is planned to perform those scans at the four interaction points using the data from the machine detectors as well as the ones from the experiments. A graphical user interface (GUI) has been developed for this purpose. We looked into procedures to quantify and if possible minimize the systematic errors coming from the measurements and the beam parameters and will discuss how we plan on using the relevant informations such as the vertex position or background measurements coming from the experiments

A Sequencer for the LHC ERA

The Sequencer is a high level software application that helps operators and physicists to commission and control the LHC. It is an important operational tool for the LHC and a core part of the control system that interacts with all LHC sub-systems. This paper describes the architecture and design of the sequencer and illustrates some innovative parts of the implementation, based on modern Java technology

A Methodology to Create 3D Body Models in Motion

[EN] Size, shape and posture are fundamental features of digital human models (DHM) to obtain accurate virtual simulations of the ergonomics of products and environments. Research on 3D body scanning, processing and modelling have enabled the generation of avatars representing specific populations and morphotypes in standing and seated postures being the basis to define size and shape of DHM. Posture is implemented with biomechanical models of the human movement. Most of the research is focused on posture control and movement tracking to analyze the variability in different contexts (e.g. driving, performing a working task). Motion capture technology used for this purpose, requires a limited number of sensors or reflective markers attached to the body according to the definition of body segments. 3D body scanning and motion capture are both technologies currently used to analyze human body shape and biomechanics to apply it to enhance digital human models. These technologies may converge on the so-called temporal 3D scanners or 4D scanners, a new technology recently developed to scan the body in motion. With this technology, it is possible to obtain sequences of dense 3D point clouds representing the movement of the body. In this paper, a novel methodology to create realistic 3D body models in motion is proposed. This method is supported by a new 4D scanning system (Move 4D) and a data driven-model. Move4D is a modular photogrammetry-based 4D scanning system. It consists of a set of 12 synchronized modules to scan full bodies with texture in motion. It can capture up to 180 fps with a resolution of 2 mm. The algorithms have been conceived and optimized to automatically process the series of raw point clouds captured. They rely on a data-driven body model including shape, pose and soft-tissue deformation trained with a large database and a deep learning model. The process is fully automatic and does not require any interactive landmarking or revision. The 3D outcome of this methodology is one noise-and artefact-free watertight mesh per frame and a model of shape, pose and soft-tissue that can be rigged with a 23-joint skeleton. This type of outcome permits their use for many applications such as simulations, augmented and virtual reality (AR/VR) or biomechanical analysis purposes.The research presented in this paper have been developed within the projects IMDEEA/2020/85 and MDEEA/2020/87. Funding requested to Instituto Valenciano de Competitividad Empresarial (IVACE), call for proposals 2020 for Technology Centers of the Comunitat Valenciana, co-funded by ERDF Funds, EU Operational Program of the Comunitat Valenciana 2014-2020.Parrilla Bernabé, E.; Ruescas, A.; Solves, J.; Ballester Fernandez, A.; Nacher Fernandez, B.; Alemany Mut, MS.; Garrido Jaen, JD. (2020). A Methodology to Create 3D Body Models in Motion. Springer. 309-314. https://doi.org/10.1007/978-3-030-51064-0_39S309314Scataglini, S., Paul, G.: DHM and Posturography. Academic Press, London (2019)Zakaria, N., Gupta, D.: Anthropometry, Apparel Sizing and Design. Woodhead Publishing, Cambridge (2019)Liberadzki, P., Adamczyk, M., Witkowski, M., Sitnik, R.: Structured-light-based system for shape measurement of the human body in motion. Sensors 18, 2827 (2018). https://doi.org/10.3390/s18092827Parrilla, E., Ballester, A., Parra, P., Ruescas, A., Uriel, J., Garrido, D., Alemany, S.: MOVE 4D: accurate high-speed 3D body models in motion. In: Proceedings of 3DBODY.TECH 2019, Lugano, Switzerland, 22–23 October 2019, pp. 30–32 (2019). https://doi.org/10.15221/19.03

Main Field Tracking Measurement in the LHC Superconducting Dipole and Quadrupole Magnets

One of the most stringent requirements during the energy ramp of the Large Hadron Collider (LHC) is to have a constant ratio between dipole-quadrupole and dipole-dipole field so as to control the variation of the betatron tune and of the beam orbit throughout the acceleration phase, hence avoiding particle loss. To achieve the nominal performance of the LHC, a maximum variation of ±0.003 tune units can be tolerated. For the commissioning with low intensity beams, acceptable bounds are up to 30 times higher. For the quadrupole-dipole integrated field ratio, the above requirements translate in the tight windows of 6 ppm and 180 ppm, while for dipole differences between sectors the acceptable error is of the order of 10^-4. Measurement and control at this level are challenging. For this reason we have launched a dedicated measurement R&D to demonstrate that these ratios can be measured and controlled within the limits for machine operation. In this paper we present the techniques developed to power the magnets during the current ramps, the instrumentation and data acquisition setup used to perform the tracking experiments, the calibration procedure and the data reduction employed

A Demonstration Experiment for the Main Field Tracking and the Sextupole and Decapole Compensation in the LHC Main Magnets

A dedicated measurement campaign was set up to test the FiDeL concept and its LSA implementation. The test was performed by demonstrating the tracking of B1 and B2 for two LHC main dipoles and one LHC main quadrupole. It also included the compensation of the b3 and b5 harmonics in the dipole magnets using the sextupole and decapole corrector magnets. In this report we present the techniques developed to power the magnets for these tests during the current ramps; the instrumentation and data acquisition setup used to perform the tracking experiments; the calibration procedure and data corrections employed; and finally the main results obtained

A Demonstration Experiment for the Forecast of Magnetic Field and Field Errors in the Large Hadron Collider

In order to reduce the burden on the beam-based feedback, the Large Hadron Collider control system is equipped with the Field Description for the LHC (FiDeL) which provides a forecast of the magnetic field and the multipole field errors. FiDeL has recently been extensively tested at CERN to determine main field tracking, multipole forecasting and compensation accuracy. This paper describes the rationale behind the tests, the procedures employed to power the main magnets and their correctors, and finally, we present the results obtained. We also give an indication of the prediction accuracy that the system can deliver during the operation of the LHC and we discuss the implications that these will have on the machine performance

Operational Experience with First Circulating Beam in the LHC

Following a series of injection tests, the first attempts to pass beam around both directions of the LHC were successful and led rapidly to circulating beam in the counter clockwise direction (beam 2) and many turns of beam 1. Unfortunately the beam commissioning was curtailed by the incident in sector 34. However, measurements performed during this first commissioning period showed that the magnet model of the machine had delivered optics close to nominal and also very good performance of beam instrumentation and supporting software. Details of the machine set-up and the commissioning procedures are given. The measurements performed and the key results from this period are described

The LHC Injection Tests

A series of LHC injection tests was performed in August and September 2008. The first saw beam injected into sector 23; the second into sectors 78 and 23; the third into sectors 78-67 and sectors 23-34-45. The fourth, into sectors 23-34-45, was performed the evening before the extended injection test on the 10th September which saw both beams brought around the full circumference of the LHC. The tests enabled the testing and debugging of a number of critical control and hardware systems; testing and validation of instrumentation with beam for the first time; deployment, and validation of a number of measurement procedures. Beam based measurements revealed a number of machine configuration issues that were rapidly resolved. The tests were undoubtedly an essential precursor to the successful start of LHC beam commissioning. This paper provides an outline of preparation for the tests, the machine configuration and summarizes the measurements made and individual system performance