1421594 20160629174357.0 CERN EDS CLAS1 Baer, T U. Hamburg (main) CERN LHC Barnes, M CERN Bartmann, W CERN Bracco, C CERN Carlier, E CERN Dehning, B CERN Garrel, N Goddard, B CERN AUTHOR|(CDS)2108505 #BEARD# Jackson, S CERN Jimenez, M DESY Kain, V CERN Mertens, V CERN Misiowiec, M Nordt, A Technische Universitaet Darmstadt Papotti, G CERN Uythoven, J CERN Wenninger, J CERN Zerlauth, M CERN Zamantzas, C CERN Zimmermann, F CERN AUTHOR|(CDS)2067941 #BEARD# CERN INTNOTE PUBLATS 000720478CER INTNOTEATSPUBL NOTE sylvia.dubourg@cern.ch CERN-ATS-Note-2012-018 MD UFOs ("Unidentified Falling Objects") are expected to be one of the major known performance limitation of the LHC. In this MD, the production mechanism and the dynamics of UFOs at the injection kicker magnets (MKIs) and the tune kicker magnets (MKQs) were studied. This was done by pulsing the MKIs and MKQs on a gap in the partly filled machine. During the MD, in total 58 UFO-type beam loss patterns were observed directly after pulsing the MKIs. None were observed after pulsing the MKQs, which provides important input for possible mitigation strategies. The temporal and spatial distribution of the UFO events could be determined by using a dedicated BLM Study Buffer, the implications for the UFO dynamics are discussed. CERN UFO CERN dust particle CERN macro particle CERN MKI CERN injection kicker magnet CERN MKQ SzGeCERN Accelerators and Storage Rings n 201205 mult. p ATS CERN. Geneva. ATS Department 1895305 http://cds.cern.ch/record/1421594/files/CERN-ATS-Note-2012-018 MD.pdf MD on UFOs at MKIs and MKQs oai:cds.cern.ch:1421594 cerncds:FULLTEXT 2012 Geneva CERN 03 Feb 2012 eng 12 PUBLIC 1415183 SzGeCERN 20170817051244.0 DOI 10.1111/j.1745-3933.2012.01221.x oai:arXiv.org:1201.1897 http://export.arxiv.org/oai2 2015-06-03 2015-06-04T05:17:30Z true arXiv Inspire 1083789 arXiv:1201.1897 eng Tombesi, F CRESST/NASA/GSFC UMCP Evidence for ultra-fast outflows in radio-quiet AGNs: III - location and energetics 2012 10 Jan 2012 Comments: 5 pages, 3 figures, accepted for publication in MNRAS Comments: 5 pages, 3 figures, accepted for publication in MNRAS arXiv Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultra-fast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ~0.0003-0.03pc (~10^2-10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between ~0.01-1 M_{\odot} yr^{-1}, corresponding to >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are log\dot{E}_K~42.6-44.6 erg s^{-1}. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies. http://arxiv.org/licenses/nonexclusive-distrib/1.0/ arXiv LANL EDS Astrophysics and Astronomy arXiv PREPRINT astro-ph.HE LANL EDS Cappi, M INAF-IASFBo Reeves, J N Keele University Braito, V Leicester University INAF-OA Brera http://arxiv.org/pdf/1201.1897.pdf Preprint n 201202 11 PREPRINT Hidden 1392869 SzGeCERN 20170816231639.0 DOI 10.1111/j.1745-3933.2011.01180.x oai:arXiv.org:1110.4827 http://export.arxiv.org/oai2 2015-05-30 2015-05-30T05:18:32Z true arXiv Inspire 940782 arXiv:1110.4827 eng Ramirez, J M On the X-ray low- and high-velocity outflows in AGNs 2011 24 Oct 2011 Comments: Accepted for publication as a Letter to the Editor in Monthly Notices of the Royal Astronomical Society Letters Comments: Accepted for publication as a Letter to the Editor in Monthly Notices of the Royal Astronomical Society Letters arXiv An exploration of the relationship between bolometric luminosity and outflow velocity, for two classes of X-ray outflows in a large sample of active galactic nuclei has been performed. We find that line radiation pressure could be one physical mechanism that might accelerate the gas we observe in warm absorber, v~100-1000 km/s, and on comparable but less stringent grounds the ultra-fast outflows (UFOs), v~0.03-0.3c. If comparable with the escape velocity of the system; the first is naturally located at distances of the dusty torus, ~ 1 pc, and the second at sub-parsec scales, ~ 0.01 pc, in accordance with large set of observational evidence existing in the literature. The presentation of this relationship might give us key clues for our understanding of the different physical mechanisms acting in the center of galaxies, the feedback process and its impact on the evolution of the host galaxy. http://arxiv.org/licenses/nonexclusive-distrib/1.0/ arXiv LANL EDS Astrophysics and Astronomy arXiv Astrophysics and Astronomy arXiv PREPRINT astro-ph.CO LANL EDS astro-ph.HE LANL EDS Tombesi, F http://arxiv.org/pdf/1110.4827.pdf Preprint n 201143 11 PREPRINT Hidden 1382375 SzGeCERN 20170816211509.0 DOI 10.1088/0004-637X/742/1/44 oai:arXiv.org:1109.2882 http://export.arxiv.org/oai2 2015-05-30 2015-05-30T05:17:58Z true arXiv Inspire 927203 arXiv:1109.2882 eng Tombesi, F NASA/GSFC/CRESST UMCP UNIBO INAF-IASFBO Evidence for ultra-fast outflows in radio-quiet AGNs: II - detailed photo-ionization modeling of Fe K-shell absorption lines 2011 14 Sep 2011 Comments: Accepted for publication in ApJ Comments: Accepted for publication in ApJ arXiv X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blueshifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \sim10,000km/s (\sim0.03c) up to \sim100,000km/s (\sim0.3c), with a peak and mean value of \sim42,000km/s (\sim0.14c). The ionization parameter is very high and in the range log\xi 3-6erg s^{-1} cm, with a mean value of log\xi 4.2 erg s^{-1} cm. The associated column densities are also large, in the range N_H\sim10^{22}-10^{24} cm^{-2}, with a mean value of N_H\sim10^{23} cm^{-2}. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets. http://arxiv.org/licenses/nonexclusive-distrib/1.0/ arXiv LANL EDS Astrophysics and Astronomy arXiv PREPRINT astro-ph.HE LANL EDS Cappi, M INAF-IASFBO Reeves, J N Keele University Palumbo, G G C UNIBO Braito, V Leicester University Dadina, M INAF-IASFBO http://arxiv.org/pdf/1109.2882.pdf Preprint n 201137 11 PREPRINT Hidden 1379457 20240223164507.0 oai:cds.cern.ch:1379457 cerncds:FULLTEXT cerncds:CERN:FULLTEXT cerncds:CERN ARTICLE ConferencePaper Velghe, B CERN Holzer, E CERN Dehning, B CERN Nordt, A CERN Sapinski, M CERN Emery, J CERN Zamantzas, C CERN Effinger, E CERN Marsili, A CERN Wenninger, J CERN Baer, T CERN Schmidt, R CERN Yang, Z Ecole Polytechnique, Lausanne CERN Zimmerman, F CERN Fuster, N Valencia U. CERN Nebot, E CERN CERN ARTICLE CERN LHC 000716912CER flora.meric@cern.ch CERN-ATS-2011-057 About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The Beam Loss Monitors (BLMs) integrate the losses in 12 different time intervals (from 40 us to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. During the 2010 run, a limiting factor in the machine availability were sudden losses appearing around the ring on the ms time scale and detected exclusively by the BLM system. It is believed that such losses originate from dust particles falling into the beam, or being attracted by its strong electromagnetic field. This document describes some of the properties of these ”Unidentified Falling Objects” (UFOs) putting special emphasis on their dependence on beam parameters (energy, intensity, etc). The subsequent modification of the BLM beam abort thresholds for the 2011 run that were made to avoid unnecessary beam dumps caused by these UFO losses are also discussed. CC-BY publication JACoW CERN EDS CLAS1 SzGeCERN Accelerators and Storage Rings n 201135 a2011 3 p ATS IPAC2011 C11-09-04 http://cds.cern.ch/record/1379457/files/CERN-ATS-2011-057.pdf https://accelconf.web.cern.ch/IPAC2011/papers/TUPC136.pdf Published version from JACoW Analysis of fast losses in the LHC with the BLM system 2011 Geneva CERN 02 Sep 2011 eng 13 1378144 TUPC136 sansebastian20110904 PUBLIC 1379150 20240223164507.0 oai:cds.cern.ch:1407950 cerncds:FULLTEXT cerncds:CERN:FULLTEXT cerncds:CERN ARTICLE ConferencePaper Baer, T CERN Hamburg U. CERN ARTICLE CERN LHC Barnes, M CERN Goddard, B CERN AUTHOR|(CDS)2108505 #BEARD# Holzer, E B CERN Jimenez, J M CERN Lechner, V CERN Mertens, V CERN Nebot Del Busto, E CERN Nordt, A CERN Uythoven, J CERN Velghe, B CERN Wenninger, J CERN Zimmermann, F CERN AUTHOR|(CDS)2067941 #BEARD# 000719800CER 000716861CER flora.meric@cern.ch evelyne.delucinge@cern.ch CERN-ATS-2011-276 CERN-ATS-2011-051 One of the major known limitations for the performance of the Large Hadron Collider are so called UFOs (Unidentified Falling Objects). UFOs were first observed in July 2010 and caused numerous protection beam dumps since then. They are presumably micrometer sized dust particles that lead to fast beam losses with a duration of about 10 turns when they interact with the beam. In 2011, the diagnostics for such events are highly increased which allows estimations of the properties, dynamics and production mechanisms of the dust particles. The state of knowledge and mitigation strategies are presented. CC-BY publication JACoW CERN EDS CLAS1 SzGeCERN Accelerators and Storage Rings SzGeCERN Engineering n 201135 a2011 4 p ATS IPAC2011 C11-09-04 http://cds.cern.ch/record/1379150/files/CERN-ATS-2011-051.pdf https://accelconf.web.cern.ch/IPAC2011/papers/TUPC137.pdf Published version from JACoW http://cds.cern.ch/record/1379150/files/CERN-ATS-2011-276.pdf Fulltext UFOs in the LHC 2011 Geneva CERN 01 Sep 2011 eng 13 1378144 TUPC137 sansebastian20110904 PUBLIC 1375436 SzGeCERN 20170816211248.0 DOI 10.1017/S1743921311027591 oai:arXiv.org:1108.2975 http://export.arxiv.org/oai2 2015-05-30 2015-05-30T05:17:17Z true arXiv Inspire 924080 arXiv:1108.2975 eng Budaj, Jan Synthetic Spectra and Light Curves of Interacting Binaries and Exoplanets with Circumstellar Material: SHELLSPEC 2011 16 Aug 2011 Comments: 6 pages, 2 figures, to appear in the Proceedings: From Interacting Binaries to Exoplanets: Essential Modeling Tools, IAU Symposium 282, held in Tatranska Lomnica, July 2011 Comments: 6 pages, 2 figures, to appear in the Proceedings: From Interacting Binaries to Exoplanets: Essential Modeling Tools, IAU Symposium 282, held in Tatranska Lomnica, July 2011 arXiv Program SHELLSPEC is designed to calculate light-curves, spectra and images of interacting binaries and extrasolar planets immersed in a moving circumstellar environment which is optically thin. It solves simple radiative transfer along the line of sight in moving media. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, ufo, shell or stars may be defined (embedded) in 3D and their composite synthetic spectrum calculated. Roche model can be used as a boundary condition for the radiative transfer. Recently a new model of the reflection effect, dust and Mie scattering were incorporated into the code. $\epsilon$ Aurigae is one of the most mysterious objects on the sky. Prior modeling of its light-curve assumed dark, inclined, disk of dust with the central hole to explain the light-curve with a sharp mid-eclipse brightening. Our model consists of two geometrically thick flared disks. Internal optically thick disk and external optically thin disk which absorbs and scatters radiation. Shallow mid-eclipse brightening may result from eclipses by nearly edge-on flared (dusty or gaseous) disks. Mid-eclipse brightening may also be due to strong forward scattering and optical properties of the dust which can have an important effect on the light-curves. There are many similarities between interacting binary stars and transiting extrasolar planets. Reflection effect which is briefly reviewed is one of them. The exact Roche shape and temperature distributions over the surface of all currently known transiting extrasolar planets have been determined. In some cases (HAT-P-32b, WASP-12b, WASP-19b) departures from the spherical shape can reach 7-15%. http://arxiv.org/licenses/nonexclusive-distrib/1.0/ arXiv LANL EDS Astrophysics and Astronomy arXiv PREPRINT astro-ph.SR LANL EDS http://arxiv.org/pdf/1108.2975.pdf Preprint n 201133 11 Comments: 6 pages, 2 figures, to appear in the Proceedings: From Interacting Binaries to Exoplanets: Essential Modeling Tools, IAU Symposium 282, held in Tatranska Lomnica, July 2011 PREPRINT Hidden 1374451 SzGeCERN 20170906041738.0 arXiv oai:arXiv.org:1108.2040 Inspire 922834 arXiv:1108.2040 eng CP3-11-25 IPHC-PHENO-11-04 IPPP-11-39 DCPT-11-78 MPP-2011-68 Degrande, Céline UFO - The Universal FeynRules Output 2011 11 Aug 2011 Comments: 30 pages, 2 figures We present a new model format for automatized matrix-element generators, the so- called Universal FeynRules Output (UFO). The format is universal in the sense that it features compatibility with more than one single generator and is designed to be flexible, modular and agnostic of any assumption such as the number of particles or the color and Lorentz structures appearing in the interaction vertices. Unlike other model formats where text files need to be parsed, the information on the model is encoded into a Python module that can easily be linked to other computer codes. We then describe an interface for the Mathematica package FeynRules that allows for an automatic output of models in the UFO format. LANL EDS Particle Physics - Phenomenology arXiv PREPRINT hep-ph LANL EDS Duhr, Claude Fuks, Benjamin AUTHOR|(CDS)2070740 #BEARD# Grellscheid, David Mattelaer, Olivier Reiter, Thomas http://arxiv.org/pdf/1108.2040.pdf Preprint n 201132 11 PREPRINT Hidden 1373713 20160628093334.0 CERN EDS CLAS1 Baer, T Hamburg U. CERN-ATS-Note-2011-065 MD CERN LHC Barnes, M CERN Bartmann, W CERN Bracco, C CERN Carlier, E CERN Chanavat, C CERN Drosdal, L U. Oslo (main) Garrel, N Goddard, B CERN AUTHOR|(CDS)2108505 #BEARD# Kain, V CERN Mertens, V CERN Uythoven, J CERN Wenninger, J CERN Zerlauth, M CERN CERN INTNOTE PUBLATS 000716328CER INTNOTEATSPUBL NOTE sylvia.dubourg@cern.ch During the MD, the production mechanism of UFOs at the injection kicker magnets (MKIs) was studied. This was done by pulsing the MKIs on a gap in the circulating beam, which led to an increased number of UFOs. In total 43 UFO type beam loss patterns at the MKIs were observed during the MD. The MD showed that pulsing the MKIs directly induces UFO type beam loss patterns. From the temporal characteristics of the loss profile, estimations about the dynamics of the UFOs are made. CERN UFO CERN dust particle CERN macro particle CERN MKI CERN injection kicker magnet SzGeCERN Accelerators and Storage Rings n 201132 08 Aug 2011 sylvia.dubourg@cern.ch 8 p ATS CERN. Geneva. ATS Department 802345 http://cds.cern.ch/record/1373713/files/CERN-ATS-Note-2011-065 MD.pdf MKI UFOs at Injection oai:cds.cern.ch:1373713 cerncds:FULLTEXT 2011 Geneva CERN 08 Aug 2011 eng 12 PUBLIC 1271085 SzGeCERN 20210422031731.0 9780691135045 print version, hardback 9781400835317 electronic version 49.5 (NL) electronic version 9781400835317 electronic version 97.5 (NL),81.25 (3U),65 (1U) electronic version 9781400835317 electronic version electronic version oai:cds.cern.ch:1271085 cerncds:BOOK SCEM 90.10.04.016.8 eng 53.01 Muller, Richard A Physics and technology for future presidents an introduction to the essential physics every world leader needs to know Princeton, NJ Princeton Univ. Press 2010 517 p paper Cover; Title; Copyright; Contents; Preface; CHAPTER 1 Energy and Power and the Physics of Explosions; CHAPTER 2 Atoms and Heat; CHAPTER 3 Gravity, Force, and Space; CHAPTER 4 Nuclei and Radioactivity; CHAPTER 5 Chain Reactions, Nuclear Reactors, and Atomic Bombs; CHAPTER 6 Electricity and Magnetism; CHAPTER 7 Waves Including UFOs, Earthquakes, and Music; CHAPTER 8 Light; CHAPTER 9 Invisible Light; CHAPTER 10 Climate Change; CHAPTER 11 Quantum Physics; CHAPTER 12 Relativity; CHAPTER 13 The Universe; Epilogue (a poem); Index; Cover; Contents; Preface: Physics Is the Liberal Arts of High-Tech; Chapter 1 Energy and Power and the Physics of Explosions; Explosions and Energy; Power; Chapter Review; CHAPTER 2 Atoms and Heat; Quandaries; Atoms and Molecules and the Meaning of Heat; Temperature; Chapter Review; CHAPTER 3 Gravity, Force, and Space; Gravity Surprises; The Force of Gravity; Push Accelerates-Newton's Third Law; Orbiting the Earth, and Weightlessness; Escape to Infinity; Air Resistance and Fuel Effi ciency; Momentum; Rockets; Airplanes, Helicopters, and Fans; Convection-Thunderstorms and Heaters Angular Momentum and TorqueChapter Review ; CHAPTER 4 Nuclei and Radioactivity; Radioactivity; Fission; Fusion; Back to the Beginning; Chapter Review; CHAPTER 5 Chain Reactions, Nuclear Reactors, and Atomic Bombs; A Multitude of Chain Reactions; Nuclear Weapons Basics; Nuclear Reactors; Nuclear Waste; Chapter Review; CHAPTER 6 Electricity and Magnetism; Electricity Is; Magnetism Is; Electricity; Electric Power; Magnets; Electric and Magnetic Fields; Electromagnets; Electric Motors; Electric Generators; Transformers; Magnetic Levitation; Rail Guns; AC versus DC; Chapter Review CHAPTER 7 Waves Including UFOs, Earthquakes, and MusicTwo Strange but True Stories; Waves; Chapter Review; CHAPTER 8 Light; High- Tech Light; What Is Light?; Color; Images; Mirrors; Slow Light; Lenses; Eyes; Telescopes and Microscopes; Spreading Light- Diffraction; Holograms ; Polarization; Chapter Review; CHAPTER 9 Invisible Light; An Opening Anecdote: Watching Illegal Immigrants Cross the Border in Darkness; Infrared Radiation; UV-"Black Light"; The Ozone Layer; Electromagnetic Radiation-an Overview; Medical Imaging; Ultrasound-Sonar (Bats and Submarines); Chapter Review CHAPTER 10 Climate ChangeGlobal Warming; Solutions; Chapter Review; CHAPTER 11 Quantum Physics; Electron Waves; Laser-a Quantum Chain Reaction; The Photoelectric Effect; Quantum Physics of Gamma Rays and X-Rays; Semiconductor Transistors; Diode Transistors; Transistors; Superconductors; Electron Microscope; Deeper Aspects of Quantum Physics; Tunneling; Quantum Computers; Chapter Review; CHAPTER 12 Relativity; A Dialogue; Events-and the "Fourth Dimension"; Time Dilation; Lorentz Contraction; Relative Velocities; Energy and Mass; General Relativity-a Theory of Gravity; Questions about Time Chapter ReviewCHAPTER 13 The Universe; Puzzles; The Solar System; Galaxies; Looking Back in Time ; Expansion of the Universe; Dark Energy; The Beginning; Theory of Everything; Chapter Review; Epilogue (a poem); Index Intro -- Cover -- Title Page -- Copyright -- Contents -- Preface -- Physics is the Liberal Arts of High-Tech -- An Ideal Student -- Physics for the Future Leader -- Chapter 1 -Energy and Power and the Physics of Explosions -- Explosions and Energy -- Power -- Chapter Review -- Chapter 2 - Atoms and Heat -- Quandaries -- Atoms and Molecules and the Meaning of Heat -- Temperature -- Chapter Review -- Chapter 3 - Gravity, Force, and Space -- Gravity Surprises -- The Force of Gravity -- Push Accelerates-Newton's Third Law -- Orbiting the Earth, and Weightlessness -- Escape to Infinity -- Air Resistance and Fuel Efficiency -- Momentum -- Rockets -- Airplanes, Helicopters, and Fans -- Convection-Thunderstorms and Heaters -- Angular Momentum and Torque -- Chapter Review -- Chapter 4 - Nuclei and Radioactivity -- Radioactivity -- Fission -- Fusion -- Back to the Beginning -- Chapter Review -- Chapter 5 - Chain Reactions, Nuclear Reactors, and Atomic Bombs -- A Multitude of Chain Reactions -- Nuclear Weapons Basics -- Nuclear Reactors -- Nuclear Waste -- Chapter Review -- Chapter 6 - Electricity and Magnetism -- Electricity Is… -- Magnetism Is… -- Electricity -- Electric Power -- Magnets -- Electric and Magnetic Fields -- Electromagnets -- Electric Motors -- Electric Generators -- Transformers -- Magnetic Levitation -- Rail Guns -- AC versus DC -- Chapter Review -- Chapter 7 - Waves Including UFOs, Earthquakes, and Music -- Two Strange but True Stories -- Waves -- Chapter Review -- Chapter 8 - Light -- High-Tech Light -- What is Light? -- Color -- Images -- Mirrors -- Slow Light -- Lenses -- Eyes -- Telescopes and Microscopes -- Spreading Light-Diffraction -- Holograms -- Polarization -- Chapter Review -- Chapter 9 - Invisible Light -- An Opening Anecdote: Watching Illegal Immigrants Cross the Border in Darkness -- Infrared Radiation -- UV-"Black Light". The Ozone Layer -- Electromagnetic Radiation-an Overview -- Medical Imaging -- Ultrasound-Sonar (Bats and Submarines) -- Chapter Review -- Chapter 10 - Climate Change -- Global Warming -- Solutions -- Chapter Review -- Chapter 11 - Quantum Physics -- Electron Waves -- Laser-a Quantum Chain Reaction -- The Photoelectric Effect -- Quantum Physics of Gamma Rays and X-Rays -- Semiconductor Transistors -- Diode Transistors -- Transistors -- Superconductors -- Electron Microscope -- Deeper Aspects of Quantum Physics -- Tunneling -- Quantum Computers -- Chapter Review -- Chapter 12 - Relativity -- A Dialogue -- Events-and the "Fourth Dimension" -- Time Dilation -- Lorentz Contraction -- Relative Velocities -- Energy and Mass -- General Relativity-a Theory of Gravity -- Questions about Time -- Chapter Review -- Chapter 13 - The Universe -- Puzzles -- The Solar System -- Galaxies -- Looking Back in Time -- Expansion of the Universe -- Dark Energy -- The Beginning -- Theory of Everything -- Chapter Review -- Epilogue (a poem) -- Index. Physics and Technology for Future Presidents contains the essential physics that students need in order to understand today's core science and technology issues, and to become the next generation of world leaders. From the physics of energy to climate change, and from spy technology to quantum computers, this is the only textbook to focus on the modern physics affecting the decisions of political leaders and CEOs and, consequently, the lives of every citizen. How practical are alternative energy sources? Can satellites really read license plates from space? What is the quantum physics behind i 45.00 30.00 EBLlink deleted SzGeCERN Physics in General CERN textbook BOOK BOOKSHOP CERN Central Library 53.01 MUL 201006 h 201024 21 20100612 1456 CER01 20100610 PUBLIC 0001 002902267CER https://catalogue.library.cern/legacy/1271085 BOOK MIGRATED 1251300 SzGeCERN 20191219215641.0 9781846285622 print version 9781846287619 electronic version 29.95 (NL) electronic version oai:cds.cern.ch:1251300 cerncds:BOOK EBL 336650 eng QB64.M267 522 Maunder, Michael Lights in the sky identifying and understanding astronomical and meteorological phenomena Dordrecht Springer 2007 239 p eBook Patrick Moore's Practical Astronomy Series Front Matter; Introduction; Light Pollution; Air Pollution; The Weather; The Human Eye; The Twilights; Dawn Glows; Daytime Glows; Dusk Glows; Night Lights; Halos; Rainbows; Flashes; UFOs and Alien Visitors; Oddities; Back Matter; EBL2010 SzGeCERN Astrophysics and Astronomy EBL Astronomy EBL Meteorology BOOK https://cds.cern.ch/auth.py?r=EBLIB_P_336650_0 ebook n 201012 21 20100518 1008 CER01 20100319 PUBLIC 002884409CER BOOK DELETED 1142621 SzGeCERN 20160106225112.0 9780691135496 print version, hardback oai:cds.cern.ch:1142621 cerncds:BOOK eng 573.5 Bennett, Jeffrey Beyond UFOs the search for extraterrestrial life and its astonishing implications for our future Princeton, NJ Princeton Univ. Press 2008 211 p Not held by the CERN library 25.00 20 17-Nov-2008 2 1 1 SzGeCERN Astrophysics and Astronomy BOOK BOOKSHOP h 200847 21 20101202 0959 CER01 20081127 PUBLIC 002791149CER BOOK DELETED 105213 SzGeCERN 20210422074347.0 0805333312 print version, hardback 9780805333312 print version, hardback oai:cds.cern.ch:105213 cerncds:BOOK 0009100CERCER eng 52 Goldsmith, Donald The evolving universe 2nd ed. Menlo Park, CA Benjamin-Cummings 1985 562 p paper SzGeCERN Astrophysics and Astronomy CERN UFO CERN astronomy CERN astrophysics CERN black CERN cosmology CERN evolution CERN extraterrestrial CERN galaxies CERN holes CERN intelligence CERN light CERN neutron CERN planets CERN pulsars CERN radio astronomy CERN radio CERN solar CERN stars CERN system CERN textbook, university level BOOK CERN Central Library 52 GOL n 198516 21 20081104 0837 CER01 19900127 PUBLIC 0001 000009100CER https://catalogue.library.cern/legacy/105213 BOOK MIGRATED 1425043 20251120204027.0 BUL-NA-2012-064 en fr Edited by Katarina Anthony based on regular reports by Mike Lamont, the Bulletin's correspondent from Chamonix LHC Report: Preparing for 4 TeV Dernières nouvelles du LHC : en préparation pour les 4 TeV 2012 17/02/2012 After more than two months since its stop in December, the LHC is slowly coming back from its hibernation - even if the temperature of the magnets in the tunnel has actually been getting lower and lower in recent days. The tunnel has been crowded with hundreds of people, busy with maintenance activities and preparations for the restart. The end of most activities (and the access to the tunnel) is scheduled for 21 February. On this date, the Operations team will take back ownership of the machine from the Programmed Stops Coordination team and push forward the preparations for the beam.   The cool-down of all LHC sectors (left floating at around 80 K during the Christmas break) restarted three weeks ago. At present, more than half of the machine is at nominal cryogenic temperature and the completion of the cool-down is expected by 27 February. As soon as a sector is cold, the Electrical Quality Assurance (ElQA) team starts the high-voltage qualification of the superconducting circuits, to check insulation and instrumentation integrity. These qualifications were initiated on the first Sector available (Sector 23) during the Charmonix workshop week, and have since been carried out on three other Sectors (Sectors 56,  67 and 78) without any non-conformity being found. Once the circuits have undergone the high-voltage qualification, the powering tests of the superconducting circuits begin. These tests officially started on 10 February, after the validation and preparation of the first sector. To minimize the impact on the activities requiring access to the tunnel (which will continue for a few more days), the powering tests are only being performed during the evening and at night, to cope with the safety constraints. These tests aim at pushing the performance of all LHC circuits to their operational level. The tests involve injecting current through the superconducting circuits while checking the correct behaviour of the protection mechanisms, an essential element for the safe operation of the machine. After operating at 3.5 TeV for two years, the LHC is entering another domain, with the main dipole and quadrupole circuits powered at a different current level for operation at 4 TeV. Apart from some small issues and debugging (also of the new tools used this year to improve the performance in test execution), as at the beginning of each restart after a long stop, the tests are progressing well. All superconducting circuits should be commissioned during the first week of March. A few days of machine check-out will then drive us to the first beam, planned for 14 March. Mirko Pojer for the LHC Team <hr /> LHC performance workshop summary The Chamonix workshop last week reviewed the performance of the LHC in 2011 and discussed plans for 2012 and beyond. Among other things, we can look forward to the LHC running at 4 TeV during 2012. A critical review of 2011 The performance of the machine was examined during the workshop, identifying possible improvements to critical systems such as beam instrumentation and machine protection. The high-intensity beams that the LHC collided last year have raised issues around the ring including beam-induced heating of some hardware, and problematic vacuum spikes. The present understanding of these problems and possible solutions were presented. One of the big successes of 2011 was the squeeze - the reduction of the beam size at the interaction point - that was pushed in the latter part of the year. Squeezing even further in 2012 might be possible in combination with the use of tighter collimator settings. This could give a peak luminosity of around 6x1033 cm-2s-1 compared with a maximum of 3.6x1033 cm-2s-1 in 2011. Possibilities for 2012 Steve Myers, CERN's Director for Accelerators and Technology, presented a summary of the workshop recommendations for the 2012 run. In brief, the LHC should operate at 4 TeV, with the key priorities being: delivering enough luminosity (of the order of 15 fb-1) to ATLAS and CMS to allow them to independently discover or exclude the Higgs; the proton-lead ion run; and a machine development programme that targets operation after the long technical shutdown. A run extension was not ruled out if necessary to meet the target integrated luminosity. Machine availability should be improved in 2012 thanks to a number of mitigation measures taken during the Christmas stop. These include a number of measures aimed at reducing the effects of radiation on the electronics situated in the LHC tunnel. Plans for the long shutdown of 2013/2014 The total length of the long shutdown (LS1) for the LHC is provisionally around 20 months. The main focus will be the splice consolidation work, which involves opening every magnet interconnect in the ring, and measuring carefully the resistance of each joint in the cables which carry the current between the dipoles and quadrupoles in the arcs of the LHC. It is currently estimated that 15% of the splices will be re-done; shunts and clamps will be installed across each splice. The aim is to definitively exclude the possibility of a repeat of the incident of 19 September 2008 at the highest energies expected at the LHC. Besides this, each of the LHC experiments has extensive programs of maintenance and upgrades. Some of the key LHC systems (cryogenics, vacuum, quench protection, electrical distribution, cooling, ventilation, access and RF) will undergo major maintenance and improvements. The machine after LS1 After LS1, a large number of re-training quenches of the LHC dipoles will be required in order to reach the nominal energy of 7 TeV per beam. Therefore, the beam energy in the first years after LS1 is expected to be around 6.5 TeV. The planned injector upgrades will not have been deployed at this stage, but the injector performance still looks capable of supplying sufficient beam quality to enable the LHC to reach the design luminosity of 1x1034 cm-2s-1. Potential limitations to post-LS1 performance (quenches, radiation to electronics, UFOs) were also considered. Future projects Prospects for the LHC Injector Upgrade project and its principal client, the High-Luminosity LHC (HL-LHC), were also considered. Tentatively scheduled to start operation around 2023, HL-LHC aims to provide an ambitious 200 to 300 inverse femtobarns per year. An examination of the challenges of the HL-LHC included a look at the state of R&D for the new magnets required for the high-luminosity interaction regions. There was also an entertaining look at the even more distant future. Possible future projects under consideration include the Large Hadron electron Collider (LHeC), which involves colliding 60 GeV electrons with 7 TeV protons, and the High Energy LHC (HE-LHC), in which the beam energy of the LHC is increased from 7 to 16.5 TeV. Serious technological challenges exist for both these options. <hr /> Steve Myers, CERN Director for Accelerators and Technology, and Sergio Bertolucci, CERN Director for Research, discuss the Chamonix workshop: <script language="javascript" src="/insertplayer.js" type="text/javascript"></script><script type="text/javascript"> var flash_video_player=get_video_player_path(); insert_player_for_external('Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-0753-kbps-640x360-25-fps-audio-64-kbps-44-kHz-stereo', 'mms://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-0480-kbps-512x288-25-fps-audio-128-kbps-48-kHz-stereo.wmv', 'false', 480, 360, 'https://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-posterframe-640x360-at-10-percent.jpg', '1423359', true, 'Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-0600-kbps-maxH-360-25-fps-audio-128-kbps-48-kHz-stereo.mp4'); </script>  Après un arrêt de plus de deux mois, le LHC se réveille doucement de son hibernation - même si la température des aimants dans le tunnel est de plus en plus basse. Le tunnel a été pris d’assaut par des centaines de personnes, occupées par la maintenance et la préparation pour le redémarrage. La fin de la plupart des activités (et de l'accès au tunnel) est prévue pour le 21 février. À cette date, le groupe Opérations reprendra possession de la machine, après l'équipe de Coordination des arrêts techniques, et avancera dans la préparation du faisceau.   Le refroidissement de tous les secteurs du LHC (qui étaient à environ 80 K pendant la pause de Noël) a redémarré il y a trois semaines. À l'heure actuelle, plus de la moitié de la machine est à la température cryogénique nominale, et l'achèvement du refroidissement est prévu d'ici au 27 février. Dès qu'un secteur est froid, l'équipe d’Assurance de la qualité électrique (ElQA) commence la qualification à haute tension des circuits supraconducteurs, pour vérifier l'intégrité de l'isolation et de l'instrumentation. Elle a commencé ces qualifications pendant la semaine de réunion de Chamonix sur le premier secteur disponible (secteur 23), et a depuis réalisé trois autres secteurs (secteurs 56, 67 et 78), sans constater aucune non-conformité. Une fois que les circuits sont qualifiés à haute tension par l'équipe ElQA, les tests d’alimentation des circuits supraconducteurs commencent. Ces tests ont donc commencé le vendredi 10, après validation et préparation du premier secteur. Pour minimiser l'impact sur les activités nécessitant un accès au tunnel (toujours en cours pour quelques jours), les tests en puissance sont à présent effectués seulement durant la soirée et la nuit, pour satisfaire les exigences de sécurité. Les tests visent à pousser les circuits du LHC à leur niveau opérationnel en leur injectant du courant et en s’assurant en même temps du comportement conforme des mécanismes de protection, éléments essentiels pour le bon fonctionnement de la machine. Après les deux années d'opération à 3,5 TeV, le LHC entrera dans un autre domaine. En effet, les circuits dipôles et quadripôles principaux seront alimentés par un courant plus élevé pour un fonctionnement à 4 TeV. Hormis quelques petits problèmes (principalement au niveau des logiciels et des nouveaux outils utilisés cette année pour améliorer la performance dans l'exécution des tests), comme nous le constatons au début de chaque redémarrage après un long arrêt, les essais sont en bonne voie et tous les circuits supraconducteurs devraient être mis en service au cours de la première semaine de mars. Quelques jours de contrôle de la machine nous conduiront au premier faisceau, prévu pour le 14 mars. Mirko Pojer pour l'équipe du LHC <hr /> Résumé de l'atelier sur les performances du LHC L’atelier de Chamonix, qui s’est tenu la semaine dernière, a permis d'analyser les performances du LHC en 2011 et de discuter des projets pour 2012 et au-delà. En particulier, nous nous réjouissons à la perspective d’une exploitation du LHC à 4 TeV durant l’année 2012. Un regard critique sur l’année 2011 Lors de l’atelier, on s’est attaché à examiner les performances de la machine en déterminant les améliorations qui pourraient être apportées à des systèmes critiques, tels que l’instrumentation de faisceau et la protection de la machine. Les collisions de faisceaux à haute intensité réalisées l’année dernière au LHC ont mis en évidence certains aspects à prendre en compte le long de l’anneau, notamment l’échauffement de certains matériels dû aux faisceaux, et des pics de vide problématiques. On a présenté l’état actuel des connaissances sur ces problèmes et avancé des solutions possibles. La compression du faisceau (réduction de la taille du faisceau au point d’interaction), obtenue vers la fin de l’année, fut l’une des grandes réussites de 2011. Il sera peut-être possible de comprimer encore davantage le faisceau en 2012 grâce à un paramétrage plus serré des collimateurs. On pourrait ainsi obtenir une luminosité de crête d’environ 6 x 1033 cm-2s-1, contre un maximum de 3,6 x 1033 cm-2s-1 en 2011. Possibilités pour 2012 Steve Myers, directeur des accélérateurs et de la technologie du CERN, a présenté un résumé des recommandations formulées durant l’atelier pour la période d’exploitation de 2012. En bref, le LHC devrait être exploité à 4 TeV, les priorités essentielles étant les suivantes : fournir à ATLAS et CMS une luminosité suffisante (de l’ordre de 15 fb-1) qui leur permette, indépendamment l’une de l’autre, soit de découvrir le Higgs, soit de l’exclure ; réaliser l’exploitation proton-ion plomb ; et lancer le programme de développement de la machine axé sur l’exploitation après le long arrêt technique. Il n’est pas exclu de prolonger l’exploitation pour pouvoir atteindre la luminosité intégrée visée. En 2012, la disponibilité de la machine devrait être améliorée grâce à un certain nombre de mesures d’atténuation prises pendant l’arrêt technique de fin d’année, dont certaines visaient à réduire les effets des rayonnements sur l’électronique située dans le tunnel du LHC. Projets pour le long arrêt de 2013-2014 La durée totale du long arrêt (LS1) du LHC est fixée provisoirement à 20 mois environ. Les équipes concentreront leurs efforts sur la consolidation des connexions électriques. Il s’agira d’ouvrir chacune des interconnexions d’aimants le long de l’anneau et de mesurer avec soin la résistance de chaque connexion transportant le courant entre le dipôle et les quadripôles des arcs du LHC. À ce jour, on estime que 15 % des connexions devront être refaites ; des dérivations et des brides de serrage seront installées au niveau de chaque connexion. Le but est d’exclure de manière définitive le risque que se reproduise l’incident survenu le 19 septembre 2008 aux énergies les plus élevées prévues pour le LHC. Parallèlement, chacune des expériences LHC a un vaste programme de travaux de maintenance et d’amélioration, lesquels seront importants pour certains des systèmes essentiels du LHC (cryogénie, vide, système de protection contre les transitions résistives, distribution électrique, refroidissement, ventilation, accès et RF). La machine après le long arrêt technique Après le long arrêt technique (LS1), les dipôles du LHC devront de nouveau être entraînés, dans le cadre d’une vaste campagne, à subir des transitions résistives afin de parvenir à l’énergie nominale de 7 TeV par faisceau. Aussi, l’énergie de faisceau dans les premières années qui suivront le LS1 devrait-elle se situer aux environs de 6,5 TeV. Les améliorations prévues pour le système d’injection n’auront alors pas encore été réalisées, mais la performance du système devrait permettre d’offrir une qualité de faisceau suffisante pour que la luminosité nominale du LHC atteigne 1 x 1034 cm-2s-1. Il a en outre été question des aspects susceptibles de limiter la performance après le LS1 (transitions résistives, effets des rayonnements sur l’électronique, UFO). Projets futurs      Les perspectives pour le projet d’amélioration des injecteurs du LHC (LIU) et son principal client, le LHC haute luminosité (HL-LHC), ont également été examinées. Le HL-LHC, dont le début de l’exploitation a provisoirement été fixé aux environs de 2023, a pour ambition de fournir 200 à 300 fb-1 par an. On a passé en revue les défis que présentera le projet HL-LHC et on a notamment fait le point sur l'état d'avancement de la R&D pour les nouveaux aimants destinés aux régions d’interaction haute luminosité. On a également évoqué de façon informelle l’avenir encore plus lointain. Parmi les futurs projets envisageables figurent le Grand collisionneur hadron-électron (LHeC), qui ferait entrer en collision des électrons de 60 GeV avec des protons de 7 TeV, et le LHC haute énergie (HE-LHC), dans lequel l’énergie de faisceau du LHC serait portée de 7 à 16,5 TeV. Ces options présentent toutes les deux de sérieux défis technologiques. <hr /> Steve Myers, directeur des accélérateurs et de la technologie au CERN, et Sergio Bertolucci, directeur de la recherche au CERN, font le point sur l'atelier de Chamonix (en anglais) :      <script language="javascript" src="/insertplayer.js" type="text/javascript"></script><script type="text/javascript"> var flash_video_player=get_video_player_path(); insert_player_for_external('Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-0753-kbps-640x360-25-fps-audio-64-kbps-44-kHz-stereo', 'mms://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-0480-kbps-512x288-25-fps-audio-128-kbps-48-kHz-stereo.wmv', 'false', 480, 360, 'https://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-posterframe-640x360-at-10-percent.jpg', '1423359', true, 'Video/Public/Movies/2012/CERN-MOVIE-2012-011/CERN-MOVIE-2012-011-0600-kbps-maxH-360-25-fps-audio-128-kbps-48-kHz-stereo.mp4'); </script> NO CERN Bulletin video ONLINE 3 08/2012 CERN Bulletin 3 09/2012 CERN Bulletin bulletin-editors@cern.ch student.journalist@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1425043 BULLETINNEWS MIGRATED 1422991 20251120204023.0 BUL-NA-2012-050 en fr Bulletin's correspondent from Chamonix 4th report from the LHC performance workshop Dernières nouvelles de l'atelier sur les performances du LHC(4) 2012 10/02/2012  On a relatively warm Thursday morning in Chamonix (-7 Celsius) the workshop looked at what things would be like after the upcoming long shutdown (LS1 -  2013/14). A large number of re-training  quenches of the LHC dipoles will be required in order to reach the nominal energy of 7 TeV so the beam energy in the first years after LS1 is expected to be around 6.5 TeV. The planned injector upgrades will not have been deployed at this stage, but the injector performance still looks capable of supplying sufficient beam quality to enable the LHC to reach the design luminosity of 1x1034 cm-2s-1.   A lot has been learned operating at 3.5 TeV over the last couple of years and many improvements have been made in the magnet powering and protection systems. The prospects for post-LS1 machine availability are encouraging. Potential limitations to post-LS1 performance (quenches, radiation to electronics, UFOs) were also considered. The evening was spent considering the more dim and distant future and the prospects for the LHC Injector Upgrade project and its client, the High-Luminosity LHC (HL-LHC), tentatively scheduled to start operating around 2023. The goals of the HL-LHC are ambitious (200 - 300 inverse femtobarns per year) and the demands on the upgraded injectors reflect this. The devil is in the detail but it's clear a lot of work remains to be done.  À Chamonix, il faisait un peu moins froid ce jeudi (-7° C). Les discussions ont porté sur ce qui nous attend après le long arrêt à venir (LS1, en 2013-2014). Les dipôles du LHC devront de nouveau être entraînés, dans le cadre d’une vaste campagne, à subir des transitions résistives afin de parvenir à l’énergie nominale de 7 TeV, de sorte que l’énergie du faisceau dans les premières années qui suivront le long arrêt LS1 devrait se situer aux environs de 6,5 TeV. Les améliorations prévues pour le système d’injection n’auront alors pas encore été réalisées, mais la performance du système devrait permettre d’offrir une qualité de faisceau suffisante pour que la luminosité nominale du LHC atteigne 1x1034 cm-2s-1.   On a beaucoup appris lors de l’exploitation à 3,5 TeV ces deux dernières années et un grand nombre d’améliorations a été apporté aux systèmes de protection et d’alimentation des aimants. Les perspectives pour la disponibilité de la machine après le long arrêt LS1 sont encourageantes. Il a en outre été question des aspects susceptibles de limiter la performance après le long arrêt LS1 (transitions résistives, effets des rayonnements sur l’électronique, UFO). En soirée, les participants ont envisagé l’avenir plus lointain et les perspectives pour le projet d’amélioration des injecteurs du LHC (LIU) et son client, le LHC haute luminosité (HL-LHC), dont le début de l’exploitation a provisoirement été fixé aux environs de 2023. Les objectifs du projet HL-LHC sont ambitieux (200 à 300 fb-1 par an) ; les exigences requises pour l’amélioration des injecteurs en sont la conséquence. Le diable est dans les détails, et une chose est sûre : il reste encore beaucoup à faire.   NO CERN Bulletin noicon ONLINE 1 06/2012 CERN Bulletin 1 07/2012 CERN Bulletin bulletin-editors@cern.ch student.journalist@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1422991 BULLETINNEWS MIGRATED 1372204 20251120203926.0 BUL-NA-2011-204 en fr Mike Lamont for the LHC Team LHC Report: 2 inverse femtobarns! Dernières nouvelles du LHC : 2 femtobarns inverses ! 2011 02/08/2011  The LHC is enjoying a confluence of twos. This morning (Friday 5 August) we passed 2 inverse femtobarns delivered in 2011; the peak luminosity is now just over 2 x1033 cm-2s-1; and recently fill 2000 was in for nearly 22 hours and delivered around 90 inverse picobarns, almost twice 2010's total.   In order to increase the luminosity we can increase of number of bunches, increase the number of particles per bunch, or decrease the transverse beam size at the interaction point. The beam size can be tackled in two ways: either reduce the size of the injected bunches or squeeze harder with the quadrupole magnets situated on either side of the experiments. Having increased the number of bunches to 1380, the maximum possible with a 50 ns bunch spacing, a one day meeting in Crozet decided to explore the other possibilities. The size of the beams coming from the injectors has been reduced to the minimum possible. This has brought an increase in the peak luminosity of about 50% and the 2 x 1033 cm-2s-1 level has now been passed. The next stage is to adiabatically increase the bunch intensity with the all out maximum being around 1.6 x 1011 protons per bunch. The mechanics of squeezing further are reasonably complicated and this possibility has been shelved until after the next technical stop. The higher peak luminosity has given some impressive production rates and we are seeing over 6 inverse picobarn an hour at the start of a fill. However, recently operational efficiency has been hit and fills have been lost. These difficulties have been caused by electrical network glitches, the effects of radiation on electronics, vacuum spikes, and UFOs, among other things. Some of these are clearly related to high intensity and high luminosity; it might be said that we are victims of our own success. Nevertheless on 2 August the LHC managed 90 inverse picobarns in one day.  Le LHC semble actuellement en mode 2. Ce matin (vendredi 5 août), nous avons en effet passé la barre des 2 femtobarns inverses produits en 2011 ; le pic de luminosité est maintenant à un peu plus de 2 x1033 cm-2s-1 ; et le récent remplissage 2000 a duré près de 22 heures et a produit environ 90 picobarns inverses, soit presque deux fois le total atteint en 2010.   Si nous souhaitons accroître la luminosité, nous pouvons augmenter le nombre de paquets, augmenter le nombre de particules par paquet, ou réduire la dimension transversale des faisceaux au point d’interaction. La taille du faisceau peut être modifiée de deux manières : soit en réduisant la taille des paquets injectés, soit en comprimant davantage le faisceau à l’aide des aimants quadripolaires situés de part et d’autre des expériences.  Le nombre de paquets ayant déjà été porté à 1 380 - le maximum possible avec un intervalle entre paquets de 50 ns - il a été décidé, lors d’une réunion tenue à Crozet, d’explorer les autres possibilités. La taille des faisceaux provenant des injecteurs a été réduite à son minimum. Cela a entraîné une hausse d'environ 50% de la luminosité de crête et le niveau de 2 x 1033 cm-2 s-1 a été dépassé. La prochaine étape consiste en une augmentation adiabatique de l’intensité du faisceau jusqu’à un maximum d'environ 1,6 x 1011 protons par paquet. Les techniques permettant une compression plus grande sont relativement complexes et cette possibilité a été mise de côté en attendant le prochain arrêt technique. La luminosité de crête plus élevée a entraîné une production impressionnante : plus de 6 pb-1 ont pu être mesurés en début de remplissage. Cependant, l’efficacité opérationnelle de la machine a récemment été perturbée et des injections de particules ont été perdues. Ces difficultés sont dues, entre autres, à des défaillances du réseau électrique, aux effets du rayonnement sur les systèmes électroniques, à des irrégularités dans le système de vide ou aux UFO. Elles sont, pour certaines d’entre elles, directement liées aux hauts niveaux d’intensité et de luminosité ; nous sommes, en quelque sorte, victimes de notre propre succès. Le 2 août, le LHC est tout de même parvenu à produire 90 pb-1 en une seule journée, et affiche un total de 1,9 fb-1 pour l’ensemble de l’année en cours. NO CERN Bulletin noicon 3 32/2011 CERN Bulletin 3 33/2011 CERN Bulletin 3 34/2011 CERN Bulletin bulletin-editors@cern.ch student.journalist@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1372204 BULLETINNEWS MIGRATED 1368917 20251120203923.0 oai:cds.cern.ch:1368917 cerncds:FULLTEXT BUL-NA-2011-191 en fr Mike Lamont for the LHC Team LHC Report: Rocky Recovery Dernières nouvelles du LHC : une reprise laborieuse 2011 20/07/2011  The last technical stop finished on Friday 8 July, but the machine returned to its pre-stop performance level over a week later.   <div class="phlwithcaption"> <div class="imageScale"><a target="_blank" href="https://lhc-statistics.web.cern.ch/LHC-Statistics/"><img height="216" width="300" alt="" src="http://cds.cern.ch/record/1368917/files/LHC_Report(2)_image.png?subformat=icon" /></a></div> Efficiency of LHC fills between 16 July and 20 July, 2011. </div> The cryogenics team had the entire ring cold by Saturday morning and the usual post-technical stop tests with circulating beams started soon after. Unfortunately, they were interrupted by a major perturbation to CERN’s electrical network caused by an impressive thunderstorm that swept over the Pays de Gex. There were major knock-on effects, including the loss of cooling to the cryogenics and an inevitable recovery period once normal service had been re-established. The beams were circulating again by Tuesday afternoon and the post-technical stop checks continued, beefed up with further tests to address a number of issues related to the power cut.  Before the stop, the LHC had managed to get 1380 bunches per beam into collisions and the plan was to ramp back up relatively quickly to this level via fills with 48, 264, and 840 bunches per beam. 48 and 264 bunches passed off reasonably smoothly. However, 840 bunches proved more difficult with three consecutive fills lost at high energy due to UFOs. UFOs are a <a target="_blank" href="http://cdsweb.cern.ch/journal/CERNBulletin/2011/24/News%20Articles/1357318">regular feature</a> of operation and they sometimes appear in bursts around one hour after the injection process. Usually these UFOs generate losses below the dump threshold, but following the stop they were stronger than usual. Operations opted to wait at 450 GeV for an hour to let the UFOs pass before ramping and this allowed for three fills - one with 840 bunches and two with 1092 bunches - that led the way back to physics with 1380 bunches. The evening of Monday 18 June saw a 1380 bunch fill go into 'Stable beams' with an initial luminosity of between 1.4 and 1.5 x1033 cm-2s-1 – another new record. The UFOs have since quieted down. With 1380 nominal bunches, the LHC is now dealing with around half design intensity. There are ongoing issues with UFOs, the effects of radiation on electronics, vacuum activity and so on. Mitigating these effects and learning to live with high intensity is all part of the process, and the current aim is to re-establish stable conditions and realize the potential of the machine to deliver some serious integrated luminosity.        Le dernier arrêt technique a pris fin le vendredi 8 juillet, mais il aura fallu une semaine pour que la machine retrouve son niveau de performance d’avant arrêt.   <div class="phlwithcaption"> <div class="imageScale"><a target="_blank" href="https://lhc-statistics.web.cern.ch/LHC-Statistics/"><img height="216" width="300" alt="" src="http://cds.cern.ch/record/1368917/files/LHC_Report(2)_image.png?subformat=icon" /></a></div> Statistiques sur l'exploitation du LHC entre le 16 et le 20 juillet 2011. </div> L’équipe responsable de la cryogénie avait remis à froid la totalité de l’anneau samedi matin, et les tests avec faisceaux en circulation qui font habituellement suite à un arrêt technique ont débuté peu après. Ils ont malheureusement été interrompus par une importante perturbation sur le réseau électrique du CERN due à un violent orage qui s’est abattu sur le Pays de Gex. Cet orage a eu des répercussions importantes, notamment une perte de refroidissement au niveau du système cryogénique et une inévitable période de reprise une fois la situation revenue à la normale. Mardi après-midi, les faisceaux circulaient de nouveau et les vérifications se sont poursuivies, complétées par de nouveaux tests destinés à contrôler un certain nombre d’aspects liés à la coupure d’électricité. Avant l’arrêt, le LHC avait réussi à fonctionner avec 1 380 paquets par faisceau et il était prévu de revenir relativement rapidement à ce niveau grâce à des injections de 48, 264 puis 840 paquets par faisceau. Les injections à 48 et 264 paquets se sont déroulées sans encombre. Le passage à 840 paquets a toutefois été plus difficile, trois remplissages consécutifs ayant été perdus à haute énergie en raison de poussières microscopiques (les UFO). Ces poussières sont<a target="_blank" href="http://cdsweb.cern.ch/journal/CERNBulletin/2011/24/News%20Articles/1357318"> habituelles de l’exploitation</a>. Elles apparaissent parfois en jets environ une heure après le début de l’injection. Habituellement, elles entraînent des déperditions de faisceau qui n’atteignent pas le seuil déclenchant l’arrêt du faisceau, mais cette fois-ci, elles ont été plus importantes que d’ordinaire. Il a été décidé de maintenir le faisceau à 450 GeV pendant une heure avant de remonter en énergie, de manière à laisser les poussières passer, ce qui a permis de réaliser trois injections (une avec 840 paquets et deux avec 1 092 paquets), qui ont de nouveau ouvert la voie à une exploitation à 1 380 paquets. Lundi 18 juin au soir, une injection à 1 380 paquets a débouché sur des « faisceaux stables » avec une luminosité initiale comprise entre 1,4 et 1,5 x 1033cm-2s-1 - un nouveau record. Depuis, les poussières n’ont pas refait parler d’elles. Avec 1 380 paquets nominaux, le LHC est à présent à mi-chemin de son intensité nominale. Certains aspects restent à surveiller (poussières microscopiques, effets des rayonnements sur l’électronique, vide, etc). Atténuer ces effets et apprendre à vivre avec de hautes intensités fait partie du jeu ; l’objectif est actuellement de rétablir des conditions stables et d'atteindre au mieux le potentiel de luminosité intégrée de la machine.  NO CERN Bulletin noicon 3 30/2011 CERN Bulletin 3 31/2011 CERN Bulletin 20553 http://cds.cern.ch/record/1368917/files/LHC_Report(2)_image.png 41582 http://cds.cern.ch/record/1368917/files/LHC_Report(2)_image.png?subformat=icon icon Bulletin-Editors@cern.ch antonella.del.rosso@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1368917 BULLETINNEWS MIGRATED 1361756 20121211105548.0 CMSBUL-ARTICLE-2011-031 A. Ball W. Zeuner TECHNICAL COORDINATION 2011 27/06/2011  1 Operational experience 2011 1.1 Overview Starting on a positive note, it is encouraging that, for the period of this report, the operation of CMS and its entire infrastructure at Point 5 was remarkably stable and efficient. No luminosity was lost due to failures of common systems or infrastructure. The major faults were two failures of rack ventilation turbines, a leak in a water pump in the endcap circuit and the first fast dump of the magnet since underground commissioning. As the rack ventilation units have two turbines, these single turbine failures were tolerated until the next possible access. The water pump survived until the end of the fill after which the circuit was switched to a reserve pump (which in principle is also possible “on the fly”). A faulty position controller of a cryo-valve serving the cryo-power leads caused a spontaneous closure of the valve leading to the fast dump of the magnet. In this case, CMS was lucky once again, since the incident happened on the first day of the May technical stop. The magnet was recovered in record time, just less than four days. It would be a mistake to misinterpret the recent excellent technical performance, over-reliant on good fortune, as evidence that further consolidation and improvement are unnecessary. 1.2 Short accesses CMS subdetectors made regular use of access possibilities when LHC had to stop for technical reasons. Though only one access for HCAL was mission-critical for high quality data-taking, several components, in particular power supply systems, showed disturbingly high failure rates, which might become critical in case the frequency of LHC accesses drops. 1.3 Major incidents On 23rd June, the LHC power network was hit by a lightning-induced failure of a pair of 18-kV substations. All cooling and ventilation was lost with the most severe consequence that the cold box stopped. Due to the investment in ride-through over the last year and an outstanding reaction from CMS subsystem and common-system field coordinators plus the TE, EN and PH department piquet teams, the CMS magnet was able to survive the incident at full field, saving what would otherwise have been an unnecessary on-off-on cycle. Recent measurements of the residual resistance ratio of the high purity aluminium stabiliser of the solenoid conductor indicate that it remains prudent to minimise the number of on-off cycles, currently standing at 51, to 200-300. The six-cycle maximum targeted for 2011 remains within reach. The key features for minimising the impact of the 23rd June incident were the electrical system filtering, the UPS, the high capacity of the reserve helium dewar and the rapid unloading of the cooling system to focus inherent remaining cooling capacity on the busbar circuit until the towers and chillers could be restarted. A first “post mortem” analysis showed that only minor damage was sustained. In particular only a single power supply in the UXC had to have communication re-established by hand, showing that the equipment in the UXC is robust and well-controlled remotely. The UPS coverage on the surface has to be improved, the observed failure of the ventilation can easily be prevented and some computers have to be better protected to simplify the restart. 1.4 Cooling system Since January, two substantial water leaks and 20 micro-leaks were detected. One of the big leaks was detected by the new leak detection system, all the rest by manual inspections. All but one (muon circuit) were in the rack circuit. Based on this observation, the cooling team intends to modify the joints in critical racks (mostly Tracker) where they are often hard to access. There were several unforeseen stoppages of cooling systems during maintenance of neighbouring ones, due to faulty procedures or interdependencies. No consequences for data-taking resulted, but these incidents confirm the need for a consolidation program, part of the upgrade work foreseen for the next shutdown. This will decouple the most critical circuits, in particular the magnet busbar circuit, which will be made completely independent to avoid inadvertent magnet ramp down. Following the intensive investment in the fluorocarbon cooling plants during the 2010/’11 year-end stop and subsequent technical stops by the CMS Tracker teams, EN-CV-DC and CMS cooling coordination, it is very pleasing to note the very low leak rate of C6F14 which is now being sustained. The teams successfully isolated the main remaining leak and implemented extensive measures to reduce the pressure transients suspected of causing such leaks. 1.5 Beam Radiation Monitoring The detector protection aspects of BRM are functioning with the required reliability. For the first time (during the LHC “UFO” event of 22nd May), beam condition monitor signals reached a large fraction (93%) of the abort threshold. The redundancy of the systems will soon be improved by the inclusion of BCM1L (leakage current diamond detectors at ±1.8 m) into the abort logic. The rapid increase in luminosity and bunch intensity has resulted in the large Beam Scintillation Counters reaching saturation and no longer being very useful as a background monitor for pp operation. The BSC upgrade is in the early planning phase with projected installation in 2014. A project kick-off workshop is planned for 22nd July 2011. The BRM group is currently switching to BCM1F to provide background measurements, but the great potential of this single-crystal diamond monitor has not yet been realised, due to manpower shortages. 2 Facilities for supporting operation, maintenance and upgrade 2.1 Building 904 The commissioning of the CSC production line in Building 904 is progressing well. On 15th June, gluing of the first cathode panel and winding of the first anode panel for the first ME4/2 CSC chamber were finished. Preparations for the RPC production line continue, with the order for climate-controlled rooms imminent. Gas distribution and the central cooling plant are progressing on schedule. The intention is to be ready to start RPC prototype construction in late autumn. Meanwhile, the metallo-textile CMS storage tent behind building 904 is more than half-filled with installation tools from SX5 and the ISR. 2.2 Point 5 Surface Assembly Building, SX5 The SX5 building is now almost completely cleared of installation tooling, which finally releases space to start the conversion into the future maintenance and repair centre of CMS. Technical specifications for the shell structure of the pixel laboratories in the SHL alcove will be issued shortly. The order for installation of a first floor (HCAL electronics lab) in the SL51 alcove has been placed and the next step will be to setup the radiation-protection zone perimeter on the floor of SX5 proper. This zone, which will house a workshop for activated detectors and a storage zone for activated components, will soon be fenced off by concrete blocks and equipped with access-controlled entry. Later the adjacent storage and working areas for subdetectors and infrastructure will be installed, with priority on the gas detector areas, as the muon detector projects have to give up the bulk of their remaining zones in ISR by the end of 2011. 3 Planning 3.1 Long Shutdowns The current baseline CERN planning envisages Long Shutdown 1 (LS1) starting at the end of 2012 and lasting 18 months, with Long Shutdown 2 (LS2) starting at the end of 2017, and having a duration driven by experiment requirements. Variants on this planning are being considered and, although no decision will be taken for some months, CMS must make contingency plans to deal with the challenges that may result from the baseline and from alternative scenarios, which also helps inform our input to the decision-making process. One particularly challenging option would be a delayed start of Long Shutdown 1 by four-five months and a delay (or creep) of LS2 until the end of 2018. The duration of LS1 and the performance limits of the LHC thereafter are key ingredients of the planning process. In this context the recent review recommendation that LHC collimator upgrades in the IR3 dispersion suppressors can be postponed for three years without affecting nominal performance at 7 TeV/beam is highly significant and should soon lead to a reliable estimate of the duration of LS1 (probably 20 months). It is already clear that very careful planning and prioritisation will be necessary to fit all the required work into the available time. Technical Coordination will use this collaboration week to discuss possible scenarios in some detail. Underlying the planning process is the need to always have contingency plans in hand for unexpected LHC repairs of varying duration. 3.2 Year-end technical stops The year-end technical stops are a potentially vital ingredient in the overall consolidation and upgrade plan as well as being essential for maintenance and repair. Based on the many uncertainties in the current planning, Technical Coordination and the EAM team are paying particular attention to the options for the 2011/’12 and 2016/’17 year-end stops. The first offers possibilities to start Phase 1 upgrade work, the second (suitably extended) may, in certain scenarios, be the only logical window for installation of the Phase 1 (four-layer, low mass) pixel tracker. A provisional decision on whether to open CMS in winter 2011/’12 will be taken in September, weighing the risks to physics performance in 2012 against the benefits in 2012 and beyond. Discussions of potential work packages and their preparatory work will continue during this CMS week. 4 Magnet, Infrastructure and Common Systems Projects Several common systems or infrastructure projects, centrally managed by Technical Coordination, are already in preparation, mostly for execution in LS1. 4.1 Common Systems: Beampipe The dimensions and tolerances of the new central beampipe, matching the Phase 1 Pixel Tracker upgrade, have been fixed and discussed in the LEB meetings. The final aperture calculation, vacuum simulation and mechanical stress investigations are ongoing. The proposed inner diameter of the central beryllium cylinder is 43.4 mm and at ± 1.45 m this flares into a conical part along η = 4.9. The metals aluminium, beryllium, and AlBeMet (a 38%/62% aluminium-beryllium alloy) are under investigation as an alternative, replacing stainless steel in the outer cones ± 1.95 m and possibly also up to ± 3.12 m. AlBeMet has excellent mechanical properties, will become much less activated than stainless steel, but is subject to the same handling and surface protection regulations as beryllium. Final approval of the dimensions will be requested from the LMC in a few weeks, with a view to completing the design, holding an EDR and placing the order before the end of the year. The walls of the new 21.7-mm radius central pipe can be guaranteed to be initially placed clear of the virtual 17-mm radius cylinder joining the bores of the two TAS absorbers. However, time-dependent tolerances (such as cavern-floor movements) may lead to this condition being unsustainable over the potential three-four-year period between long shutdowns. The actual position of the pipe wall can be verified in a few days via nuclear interaction tomography but it is advisable that the high-β* operation requested by TOTEM for total cross-section measurements be completed in the first year after LS1 to avoid the need for a lengthy and costly opening for beampipe re-positioning. 4.2 Common systems: Magnet Cryogenics As mentioned in previous reports and in the Upgrade Technical Proposal, failure of one or both of the helium compressor pair in the surface cryo-plant is a critical single-point failure for CMS and urgent action is being taken to specify custom-built components which can reduce the impact of this failure from four-six months to one month. This vulnerability is rendered more urgent by the recent sudden failure of similar (but not identical) compressors in the LHC cryo-plants. The plan during LS1 is to implement the full redundancy for which provision was made in the design. A funding mechanism is being discussed in the appropriate CMS boards. 4.3 Common systems: Radiation shielding Easily deployed radiation shielding will be necessary to allow access to all parts of CMS, respecting the ALARA principle and minimising individual and collective dose to personnel. Recently a break-through has been made in the design of shielding for the region between the Tracker bulkhead and z = 10.7 m. It is foreseen to finalise the design over the summer, hold an EDR in autumn and starting production towards the end of the year. 4.4 Endcap Muon: YE4 Although coordinated as part of the endcap muon upgrade, the YE4 shielding wall is an integral part of the overall CMS shielding strategy for nominal luminosity. It is designed to absorb radiation due to particles escaping from the forward shielding and reflecting back off the headwall. The first material was delivered to HMC-3, Taxila, Pakistan in April. Approval of the cutting scheme, quality control plan and inspection points was agreed in June, and material for the first sector cases in now being cut. Delivery to CERN is expected in early 2012, after which a second horizontal assembly will be done prior to filling the sectors with the shielding mixture. LS1 provides the only available window for underground assembly of the YE4s. A tooling-and-assembly EDR is planned for August 2011. 4.5 Tracking: Pixel Luminosity Telescope The PLT upgrade to the Beam Radiation Monitoring System has recently been thoroughly reviewed. The details of the review are still being analysed, but one can already congratulate all participants on the massive progress the project has made during the last six months. Installation on the BCM1 carriage during the 2011/’12 year-end stop remains possible, though challenging. A contingency to install part of the system in the empty +z CASTOR slot would be attractive in case of delays or a decision not to open the yoke.     CMS Bulletin ONLINE 2 2/2011 CMS Bulletin marzena.lapka@cern.ch CMSBULLETINARTICLE 1360708 20251120203915.0 oai:cds.cern.ch:1360708 cerncds:FULLTEXT BUL-NA-2011-160 en fr Mike Lamont for the LHC Team LHC Report: the machine - on the level Dernières nouvelles du LHC : des objectifs atteints plus tôt que prévu 2011 22/06/2011  The LHC has held the number of bunches per beam at 1092 over the last couple of weeks and has been delivering luminosity to the experiments at a healthy rate. The integrated luminosity total has already passed 1 inverse femtobarn (fb-1), which was the overall goal for the year. There was a modest celebration in the CCC to mark the occasion. Modest celebrations are now on hold until the end of this year's run or the delivery of 5 fb-1.   <div class="phlwithcaption"> <div class="imageScale"><a target="_blank" href="http://cds.cern.ch/record/1360708/files/LHCReport_image.png"><img width="300" height="230" alt="" src="http://cds.cern.ch/record/1360708/files/LHCReport_image.png?subformat=icon" /></a></div> </div> LHCb is designed to perform different types of physics searches from those at ATLAS and CMS, and is limited to a peak luminosity of about 3x1032 cm-2s-1. If the beams were to be collided head-on in the LHCb detector, this figure would be exceeded. Therefore the beams are initially separated by a few microns in the vertical plane and then, as the beam intensity decays during a fill, this separation is gently reduced to keep the luminosity constant at the acceptable maximum. This technique is known as 'luminosity levelling' and has been used successfully to deliver around 0.36 fb-1 to LHCb in 2011, well on the way to their target of 1 fb-1 for the year.   As expected, high beam intensities have introduced a number of issues including: UFOs, the effect of radiation on the electronics installed in the LHC tunnel; and beam-induced heating of some accelerator components. Understanding, and where possible mitigating, these effects is ongoing, hence the more sedate pace in pushing the beam intensity recently. The operations team has successfully pushed up the number of bunches per beam to 1236 and they hope to make the step up to 1380, the final target of 2011, before the start of next machine development (MD) period, on 29 June. The MD sessions will be followed by a 5-day technical stop, which will take us to 8 July when operation for physics will start again.   Le LHC a maintenu le nombre de paquets par faisceau à 1092 au cours des deux dernières semaines, et a fourni de la luminosité aux expériences sans désemparer. La luminosité intégrée totale a déjà franchi la barre des 1 fb-1 (femtobarn inverse), ce qui était l’objectif global pour l’année 2011. L'événement a modestement été célébré au CCC, et il faudra désormais attendre la fin de l'exploitation 2011 - ou atteindre les 5 fb-1 - pour les prochaines réjouissances.   <div class="phlwithcaption"> <div class="imageScale"><a target="_blank" href="http://cds.cern.ch/record/1360708/files/LHCReport_image.png"><img width="300" height="230" alt="" src="http://cds.cern.ch/record/1360708/files/LHCReport_image.png?subformat=icon" /></a></div> </div> LHCb est un détecteur conçu pour différents types de recherches, de celle conduites à ATLAS à celles menées à CMS, et peut recevoir une luminosité de crête maximale d’environ 3x1032 cm-2s-1. Si les faisceaux entraient en collision de manière frontale dans LHCb, cette limite serait dépassée. Par conséquent, les faisceaux sont d’abord séparés de quelques microns dans le plan vertical et, ensuite, pour s'adapter à la décroissance de l’intensité du faisceau au cours de l'injection, cette séparation est réduite progressivement de façon à toujours maintenir la luminosité au maximum acceptable. Cette technique, connue sous le nom d’égalisation de la luminosité, a bien fonctionné en 2011, lorsque la machine a livré quelque 0,36 fb-1 à LHCb, lequel est donc très bien parti pour atteindre son objectif de 1 fb-1 pour la totalité de l’année. Comme nous nous y attendions, les intensités de faisceau élevées ont entraîné un certain nombre de problèmes, notamment les « objets tombants non identifiés », l’effet des rayonnements sur l’électronique installée dans le tunnel du LHC, et l’échauffement de certains éléments de l’accélérateur provoqué par les faisceaux. Les équipes s’efforcent de mieux comprendre et, dans la mesure du possible, d’atténuer ces effets, c’est pourquoi l’augmentation de l’intensité se poursuit actuellement à un rythme plus calme. L'équipe des opérations a fait passer avec succès le nombre de paquets par faisceaux à 1236, et elle espère passer le cap des 1380, objectif final pour l'année 2011, avant le début de la prochaine phase de développement machine (MD) qui commencera le 29 juin prochain. Les sessions MD seront suivies d’un arrêt technique de 5 jours, ce qui nous amènera au 8 juillet, date de la reprise des opérations pour la physique. NO CERN Bulletin noicon ONLINE 3 26/2011 CERN Bulletin 3 27/2011 CERN Bulletin http://cds.cern.ch/record/1360708/files/LHCReport_image.png http://cds.cern.ch/record/1360708/files/LHCReport_image.png?subformat=icon icon bulletin-editors@cern.ch student.journalist@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1360708 BULLETINNEWS MIGRATED 1357318 20251120203909.0 oai:cds.cern.ch:1357318 cerncds:FULLTEXT BUL-NA-2011-139 en fr Mike Lamont for the LHC Team LHC experiences close encounters with UFOs Malgré les poussières, les records continuent à tomber 2011 09/06/2011  On 29 May, yet another record was set as 1092 bunches per beam were injected into the LHC, hitting a peak luminosity of 1.26x1033 cm-2 s-1. While running at 3.5 TeV each beam now packs a total energy of over 70 MJ – equivalent to a TGV travelling at a 70 kph.   <div class="phlwithcaption"> <div class="imageScale"><a href="http://cds.cern.ch/record/1357318/files/1105146_01-A4-at-144-dpi_image.jpg" target="_blank"><img src="http://cds.cern.ch/record/1357318/files/1105146_01-A4-at-144-dpi_image.jpg?subformat=icon" alt="" /></a></div> Operators in the LHC Control Centre happily show off their display screens after succesfully injecting 1092 bunches injected into the machine for the first time. </div> As the total beam intensity has been pushed up, the LHC has encountered a number of related problems, such as the so-called UFOs (Unidentified Falling Objects). These are thought to be dust particles falling through the beam, causing localized beam loss. The losses can push nearby beam loss monitors over the threshold and dump the beam. This is more of an annoyance than a danger for the LHC, but UFOs do reduce the operational efficiency of the machine. Despite this, the luminosity delivered to the experiments has steadily increased. On three occasions there have been over 40 inverse picobarns (pb-1) delivered in a single fill. The total for the year, at the time of writing, stands at over 800 pb-1 or 0.80 inverse femtobarn (fb-1) – well on the way to the target for the year of 1 fb-1. The program of the coming weeks is to push for even more luminosity, maximizing the total delivered to the experiments before the summer conferences. <hr /> <script language="javascript" src="http://cdsweb.cern.ch/insertplayer.js" type="text/javascript"></script> <script type="text/javascript"> var flash_video_player=get_video_player_path(); insert_player_for_external('Video/Public/Movies/2011/CERN-MOVIE-2011-079/CERN-MOVIE-2011-079-0753-kbps-640x360-25-fps-audio-64-kbps-44-kHz-stereo', 'mms://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2011/CERN-MOVIE-2011-079/CERN-MOVIE-2011-079-0480-kbps-512x288-25-fps-audio-128-kbps-48-kHz-stereo.wmv', 'false', 480, 360, 'http://mediaarchive.cern.ch/MediaArchive/Video/Public/Movies/2011/CERN-MOVIE-2011-079/CERN-MOVIE-2011-079-posterframe-640x360-at-10-percent.jpg', '1354548', true); </script>  Le 29 mai, un nouveau record a été établi avec l’injection de 1 092 paquets par faisceau dans le LHC, ce qui a permis d’atteindre une luminosité-crête de 1,26 x1033 cm-2 s-1. Lorsque la machine est exploitée à 3,5 TeV, chaque faisceau a une énergie totale de plus de 70 MJ – équivalant à un TGV circulant à la vitesse de 70 km/h.   <div class="phlwithcaption"> <div class="imageScale"><a href="http://cds.cern.ch/record/1357318/files/1105146_01-A4-at-144-dpi_image.jpg" target="_blank"><img src="http://cds.cern.ch/record/1357318/files/1105146_01-A4-at-144-dpi_image.jpg?subformat=icon" alt="" /></a></div> Dans le Centre de Contrôle du LHC, les opérateurs sont heureux de montrer les écrans affichant les 1092 paquets tout juste injectés dans la machine, et ce pour la première fois.</div> À mesure que l’intensité de faisceau augmentait, le LHC a subi plusieurs effets gênants, notamment des « objets tombant non identifiés ». Il s’agit de poussières microscopiques entrant en contact avec le faisceau et provoquant localement des déperditions. Au-delà d’un certain seuil, les détecteurs de perte de faisceau situés à proximité de la zone touchée peuvent alors être déclenchés et provoquer l’arrêt du faisceau. Il s’agit plus d’un désagrément que d’un danger pour le LHC, mais ce phénomène réduit l’efficacité opérationnelle de la machine. Cela n’a pas empêché la luminosité fournie aux expériences d’augmenter régulièrement. À trois reprises, une luminosité supérieure à 40 pb-1 a été atteinte pour un seul remplissage. La luminosité totale enregistrée pour 2011 s’élève à ce jour à plus de 800 pb-1, ou 0,80 fb-1 ; autant dire qu’on s’approche de la valeur que l’on s’est fixée pour cette année, soit 1 fb-1. L’objectif pour les prochaines semaines consistera à augmenter encore la luminosité, afin d’avoir emmagasiné le maximum de luminosité intégrée pour les expériences avant les conférences d'été. <hr /> <script language="javascript" src="http://cdsweb.cern.ch/insertplayer.js" type="text/javascript"></script> <script type="text/javascript"> var flash_video_player=get_video_player_path(); insert_player_for_external('Video/Public/Movies/2011/CERN-MOVIE-2011-079/CERN-MOVIE-2011-079-0753-kbps-640x360-25-fps-audio-64-kbps-44-kHz-stereo', 'mms://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2011/CERN-MOVIE-2011-079/CERN-MOVIE-2011-079-0480-kbps-512x288-25-fps-audio-128-kbps-48-kHz-stereo.wmv', 'false', 480, 360, 'http://mediaarchive.cern.ch/MediaArchive/Video/Public/Movies/2011/CERN-MOVIE-2011-079/CERN-MOVIE-2011-079-posterframe-640x360-at-10-percent.jpg', '1354548', true); </script> NO CERN Bulletin video 3 24/2011 CERN Bulletin 3 25/2011 CERN Bulletin http://cds.cern.ch/record/1357318/files/LHCReport_image.png http://cds.cern.ch/record/1357318/files/LHCReport_image.png?subformat=icon icon http://cds.cern.ch/record/1357318/files/1105146_01-A4-at-144-dpi_image.jpg http://cds.cern.ch/record/1357318/files/1105146_01-A4-at-144-dpi_image.jpg?subformat=icon icon bulletin-editors@cern.ch student.journalist@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1357318 BULLETINNEWS MIGRATED 1225313 SzGeCERN 20231208224955.0 oai:cds.cern.ch:1225313 cerncds:FULLTEXT PRESSCUT-V-2009-8130 eng UFO physicist have opened a gateway to hell 2009 SIS VOCUS2009 SzGeCERN Other subject PRESS CUTTING No pagination 14 May 2009 Examiner.com 2009 http://www.examiner.com Website http://doc.cern.ch/archive/electronic/other/uploader/VOCUS/PRESSCUT-V-2009-8130.txt Abstract provided by Vocus http://cds.cern.ch/record/1225313/files/PRESSCUT-V-2009-8130.txt Abstract provided by Vocus n 200948 17 20091126 1029 CER01 20091126 PUBLIC 002860865CER CUTTING 1198893 SzGeCERN 20231208224636.0 oai:cds.cern.ch:1198893 cerncds:FULLTEXT PRESSCUT-V-2009-4396 eng ET UFO global challenge armorial bearings of God particle LHC 2008 SIS VOCUS2009 SzGeCERN XX PRESS CUTTING No pagination 15 August 2008 American Chronicle 2008 http://www.americanchronicle.com Website http://doc.cern.ch/archive/electronic/other/uploader/VOCUS/PRESSCUT-V-2009-4396.txt Abstract provided by Vocus http://cds.cern.ch/record/1198893/files/PRESSCUT-V-2009-4396.txt Abstract provided by Vocus n 200932 17 20090810 0944 CER01 20090810 PUBLIC 002840748CER CUTTING 1195242 SzGeCERN 20231208224407.0 oai:cds.cern.ch:1195242 cerncds:FULLTEXT PRESSCUT-V-2009-1991 eng True confessions of an ET UFO contact 2008 SIS VOCUS2009 SzGeCERN XX PRESS CUTTING No pagination 02 September 2008 Los Angeles Chronicle 2008 http://doc.cern.ch/archive/electronic/other/uploader/VOCUS/PRESSCUT-V-2009-1991.txt Abstract provided by Vocus http://cds.cern.ch/record/1195242/files/PRESSCUT-V-2009-1991.txt Abstract provided by Vocus n 200931 17 20090730 1121 CER01 20090730 PUBLIC 002837170CER CUTTING 1460027 SzGeCERN 20170906054337.0 arXiv oai:arXiv.org:1207.0906 Inspire 1121136 arXiv:1207.0906 eng BONN-TH-2012-17 Staub, Florian Linking SARAH and MadGraph using the UFO format 2012 05 Jul 2012 Comments: 12 pages, no figures SARAH is a Mathematica package optimized for the fast, efficient and precise study of supersymmetric models beyond the MSSM: a new model can be defined in a short form and all vertices are derived. This allows SARAH to create model files for FeynArts/FormCalc, CalcHep/CompHep and WHIZARD/OMEGA. The newest version of SARAH now provides the possibility to create model files in the UFO format which is supported by MadGraph 5, MadAnalysis 5, GoSam, and soon by Herwig++. Furthermore, SARAH also calculates the mass matrices, RGEs and 1-loop corrections to the mass spectrum. This information is used to write source code for SPheno in order to create a precision spectrum generator for the given model. This spectrum-generator-generator functionality as well as the output of WHIZARD and CalcHep model files have seen further improvement in this version. LANL EDS Particle Physics - Phenomenology arXiv PREPRINT hep-ph LANL EDS http://arxiv.org/pdf/1207.0906.pdf Preprint n 201227 11 PREPRINT Hidden 1459446 20240223164703.0 CERN EDS CLAS1 ARTICLE ConferencePaper Geneva CERN 20 May 2012 Not applicable Not applicable Barnes, MJ CERN Cerutti, F CERN Ferrari, A CERN Garrel, N CERN Goddard, B CERN AUTHOR|(CDS)2108505 #BEARD# Holzer, EB CERN Jackson, S CERN Lechner, A CERN Mertens, V CERN Misiowiec, M CERN Nebot del Busto, E CERN Nordt, A CERN Uythoven, J CERN Vlachoudis, V CERN Wenninger, J CERN Zamantzas, C CERN Zimmermann, F CERN AUTHOR|(CDS)2067941 #BEARD# Fuster, N Valencia U. CERN ARTICLE 000724452CER nadia.el.mahi@cern.ch n 201227 a2012 CERN-ATS-2012-100 Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented CC-BY publication JACoW SzGeCERN Accelerators and Storage Rings 3 p ATS THPPP086 Conf. Proc. C1205201 2012 IPAC2012 C12-05-20.1 https://accelconf.web.cern.ch/IPAC2012/papers/THPPP086.pdf Published version from JaCoW 645664 1053747 http://cds.cern.ch/record/1459446/files/CERN-ATS-2012- 100.pdf 645664 2047085 http://cds.cern.ch/record/1459446/files/CERN-ATS-2012- 100.pdf?subformat=pdfa pdfa UFOs in the LHC: Observations, studies and extrapolations oai:cds.cern.ch:1459446 cerncds:FULLTEXT cerncds:CERN:FULLTEXT cerncds:CERN 2012 Baer, T CERN Hamburg U. eng 13 1445554 3936 neworleans20120520 PUBLIC 1447373 SzGeCERN 20170817235622.0 DOI 10.1111/j.1365-2966.2012.21266.x oai:arXiv.org:1205.1734 http://export.arxiv.org/oai2 2015-06-05 2015-06-06T05:16:48Z true arXiv Inspire 1113885 arXiv:1205.1734 eng Tombesi, F CRESST/NASA/GSFC University of Maryland, College Park Comparison of ejection events in the jet and accretion disc outflows in 3C 111 2012 09 May 2012 Comments: 9 pages, accepted for publication in MNRAS Comments: 9 pages, accepted for publication in MNRAS arXiv We present a comparison of the parameters of accretion disc outflows and the jet of the broad-line radio galaxy 3C 111 on sub-pc scales. We make use of published X-ray observations of ultra-fast outflows (UFOs) and new 43GHz VLBA images to track the jet knots ejection. We find that the superluminal jet coexists with the mildly relativistic outflows on sub-pc scales, possibly indicating a transverse stratification of a global flow. The two are roughly in pressure equilibrium, with the UFOs potentially providing additional support for the initial jet collimation. The UFOs are much more massive than the jet, but their kinetic power is probably about an order of magnitude lower, at least for the observations considered here. However, their momentum flux is equivalent and both of them are powerful enough to exert a concurrent feedback impact on the surrounding environment. A link between these components is naturally predicted in the context of MHD models for jet/outflow formation. However, given the high radiation throughput of AGNs, radiation pressure should also be taken into account. From the comparison with the long-term 2-10keV RXTE light curve we find that the UFOs are preferentially detected during periods of increasing flux. We also find the possibility to place the UFOs within the known X-ray dips-jet ejection cycles, which has been shown to be a strong proof of the disc-jet connection, in analogue with stellar-mass black holes. However, given the limited number of observations presently available, these relations are only tentative and additional spectral monitoring is needed to test them conclusively. http://arxiv.org/licenses/nonexclusive-distrib/1.0/ arXiv LANL EDS Astrophysics and Astronomy arXiv PREPRINT astro-ph.HE LANL EDS Sambruna, R M George Mason University Marscher, A P Boston University Jorstad, S G Boston University St. Petersburg State University Reynolds, C S University of Maryland, College Park Markowitz, A University of California, San Diego Frederic-Alexander Universitat, Bamberg http://arxiv.org/pdf/1205.1734.pdf Preprint n 201219 11 PREPRINT Hidden 1456545 20251120204110.0 BUL-NA-2012-218 en fr Mike Lamont for the LHC Team ... It’s a blooming miracle - a special LHC Report ... C'est un pur miracle - spéciales "Dernières nouvelles du LHC" 2012 19/06/2012 Wrestling a 27 km superconducting collider under control is not easy. Throw in high intensity beams and it can sometimes seem a continual, frustrating battle with the vagaries of a hugely complex problem space.   This problem space has been thoroughly explored over the last three or four years. The myriad of potential obstacles to smooth operation ranges from unidentified falling objects (UFOs), electron clouds, beam dynamics, radiation to electronics, vacuum instabilities, “transparent” software changes, Radio Frequency (RF) trips, electrical network glitches etc. etc. The huge extended systems, such as the beam loss monitors, cryogenics, and quench protection systems, have a phenomenal number of components that inevitably have occasional failures (there is, of course, a higher probability that these occur late Friday evening and over the weekend). On the cryogenics front, cooling and keeping 36,000 tonnes of magnets at 1.9 K is a challenging prerequisite for everything else that follows. Despite their complexity, we have very well behaved magnets and overall the machine is stable and magnetically reproducible. The magnets are well understood following a long and careful measurement campaign carried out during production. A sophisticated magnet model is even capable of dealing with the once feared dynamic effects. Together with the accuracy and stability of the power converters, our carefully optimized machine stays optimized. The injection, ramp and squeeze have been mastered and, as a general rule, injected beam makes it into collisions. Exploitation of the LHC’s potential is helped by the presence of excellent beam instrumentation and powerful high-level software architecture. Together with some applied intelligence, these have allowed the development of tools (e.g. measurement and correction of optics, an on-line aperture model) which have opened the way to maximizing the performance of the machine. Most notably, accurate measurements of the aperture in the regions adjacent to the experiments have allowed us to reduce the beam size at the interaction points to unexpectedly low values. The better-than-expected aperture reflects good observance of tolerances during installation and very good alignment of all elements by the survey group. The LHC has enjoyed from the start very good beam quality (both protons and ions) from the injector complex. The bunch currents have been well above, and the beam sizes well below, the nominal values quoted in the design report. The production of beam in the LINAC, Booster, PS, and SPS is distinctly non-trivial and requires continual care and attention to maintain the beam parameters, however this diligence is reflected directly in delivered luminosity. Naturally, a cautious approach marked the re-starting in November 2009 following recovery from the 2008 incident. This was most clearly reflected in the choice to run at an initial beam energy of 3.5 TeV. Having experienced first hand the destructiveness of magnetic energy, awareness of the damage potential of the beam to the machine has underpinned the operational approach and marked the subsequent evolution in beam intensity. The full and proper functioning of the extended machine protection system (MPS) has always been an absolute priority. The MPS consists of a federation of inputs from various systems into a beam interlock system (BIS). When the BIS is triggered it provokes a beam dump within 3 to 4 turns (that is, in a few hundred millionths of a second). The MPS has worked flawlessly, always pulling a beam abort when called upon to do so. In addition to the MPS, the beam drives a subtle interplay of the beam dump system, the collimation system and protection devices, all of which rely on a well-defined aperture, orbit and optics for guaranteed safe operation. Assuring this throughout high intensity operation remains paramount. Numerous interlocks are in place to ensure that posted limits are always respected. One notable feature during LHC commissioning and operation is the collective ability of CERN teams to resolve problems. There is in-depth expertise and experience on all systems, including vacuum, collimation, RF, fast kicker magnets and so on. Serious issues, such as radiation to electronics, and the lack of redundancy in protection systems, are targeted rigorously as they become apparent.   Although precision and rigour are needed when dealing with the tightly synchronized choreography and the ever present dangers of magnetic and beam energy, an open and mostly friendly atmosphere pervades. A recent visitor to an 8:30 meeting noted the lack of defensiveness, and a willingness to directly engage a problem without needing to assign blame. There is amazing dedication from everybody involved. Problems that stop the operation of the machine happen anytime, with a slight preference for nighttime and the weekend. Despite this, there is unfailing support from all teams. Coming out of the technical stop this last weekend the Machine Protection and Electrical Integrity team worked until 5 in the morning on Saturday, and the control and timing teams were in from 2 to gone 6 on Sunday morning dealing with the effects of an innocent leap second. Finally, trying to hold everything together across the accelerator complex is a talented, smart, moderately good-looking operations team who have necessarily developed an advanced sense of humour. The LHC came out of a five-day technical stop on the evening of Friday 29 June. For real-time information on the operation of the machine, visit the <a href="http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php" target="_blank">LHC Page 1</a> status page. Parvenir à dompter un collisionneur supraconducteur de 27 km n’est pas une mince affaire. Si de plus vous y injectez des faisceaux de haute intensité, vous vous trouverez aux prises avec les caprices d’un système d’une complexité extrême.   Ce système hautement complexe a été exploré de fond en comble au cours des trois ou quatre dernières années. Mille et un facteurs sont susceptibles de faire obstacle à son bon fonctionnement : objets tombants non identifiés (UFO), nuages d’électrons, dynamique du faisceau, effets des rayonnements sur l’électronique, instabilités du vide, modifications « transparentes » de logiciel, coupures de radiofréquence ou encore problèmes du réseau électrique. Les gigantesques systèmes répartis, tels que les détecteurs de perte de faisceau, la cryogénie et les systèmes de protection contre les transitions résistives, sont constitués d’un nombre phénoménal d'éléments, qui ont inévitablement leurs défaillances occasionnelles (avec, bien évidemment, une forte probabilité que celles-ci interviennent le vendredi en fin de soirée ou pendant le week-end). Du côté de la cryogénie, refroidir et maintenir 36 000 tonnes d'aimants à 1,9 K est un prérequis exigeant pour tout ce qui suit. Malgré leur complexité, nos aimants se tiennent bien et, d’un point de vue général, la machine est stable et présente une bonne reproductibilité du champ magnétique. Une longue campagne de mesures minutieuses, menée en période de production, nous a permis de bien comprendre le fonctionnement des aimants. Aujourd’hui, un modèle d’aimant très évolué est même capable de gérer les effets dynamiques qui étaient autrefois redoutés. Grâce à la précision et à la stabilité des convertisseurs de puissance, notre machine, qui a été optimisée avec soin, reste optimisée. L’injection, la montée en énergie et la compression sont maintenant maîtrisées et, en règle générale, les faisceaux injectés arrivent à entrer en collision. L’exploitation des possibilités qu’offre le LHC est facilitée par la présence d’une excellente instrumentation de faisceau et d’une puissante architecture de logiciels de haut niveau. Appliquées avec intelligence, celles-ci ont permis de mettre au point des outils (par exemple pour la mesure et la correction de l’optique ou un modèle d’ouverture en ligne) grâce auxquels la performance de la machine a été optimisée. Surtout, grâce à des mesures précises de l’ouverture dans les zones adjacentes aux expériences, nous avons pu réduire à des valeurs remarquablement basses les dimensions du faisceau aux points d’interaction. L’amélioration inespérée de l’ouverture peut être mise sur le compte du respect des tolérances au cours de l’installation et d’un très bon alignement des éléments par le groupe Métrologie. Le LHC a bénéficié dès le départ de l’excellente qualité du faisceau (de protons et d'ions) produit par le complexe d’injecteurs. Par rapport aux valeurs nominales prévues dans le rapport de conception, l’intensité des paquets est bien plus grande et la taille des faisceaux est bien plus petite. La production du faisceau dans le LINAC, le Booster du PS, le PS et le SPS est loin d’être un jeu d’enfant et exige un soin et une attention de tous les instants pour maintenir les paramètres du faisceau. Or, la luminosité obtenue en dépend directement. Naturellement, après les travaux de remise en état qui ont fait suite à l’incident de 2008, le redémarrage de novembre 2009 s’est fait sous le signe de la prudence. Cela s’est surtout traduit par le choix d’exploiter la machine à une énergie de faisceau initiale de 3,5 TeV. Ayant fait l’expérience directe de la destructivité de l’énergie stockée dans les aimants, nous étions aussi conscients du potentiel destructeur du faisceau pour la machine, ce qui nous a incités à opter pour le mode d’exploitation que nous avons choisi et a déterminé l’évolution ultérieure de l’intensité du faisceau. Pouvoir tirer pleinement parti du système de protection de la machine (MPS) a toujours été une priorité. Le MPS met à contribution divers systèmes pour produire un mécanisme de verrouillage du faisceau (BIS). Quand le BIS s’active, il provoque une éjection du faisceau en 3 à 4 tours (soit en quelques centaines de microsecondes). Le MPS fonctionne impeccablement, imposant un arrêt du faisceau chaque fois que cela est nécessaire. Outre l’apport du MPS, le faisceau impose une interaction subtile entre le système d’éjection du faisceau, le système de collimation et les dispositifs de protection, dont le bon fonctionnement repose sur une bonne définition de l’ouverture, de l’orbite et de l’optique. Se plier à ces exigences tout au long de l’exploitation haute intensité reste d'une importance capitale. De nombreux verrous ont été établis pour faire en sorte que les limites définies soient toujours respectées. La mise en service et l'exploitation du LHC ont été marquées par la capacité des équipes du CERN de résoudre ensemble les problèmes. Les équipes possèdent des compétences très poussées et une expérience approfondie de leurs systèmes respectifs, en particulier dans le domaine du vide, de la collimation, de la radiofréquence et des aimants de déflexion rapide, pour n’en citer que quelques-uns. Les problèmes tels que les effets des rayonnements sur l’électronique et le manque de redondance dans les systèmes de protection, sont ciblés avec la plus grande rigueur à mesure qu’ils apparaissent. Malgré la précision et la rigueur nécessaires pour régler le ballet des faisceaux étroitement synchronisés et les dangers permanents liés à l’énergie stockée dans les aimants et à l’énergie du faisceau, il règne un esprit d'ouverture et une atmosphère le plus souvent amicale. Récemment, un visiteur ayant assisté à une de nos réunions de 8 h 30 relevait l’absence d’attitude défensive et la volonté de s’attaquer directement au problème sans chercher à blâmer quiconque. Le dévouement des uns et des autres est tout simplement impressionnant. Les problèmes entraînant un arrêt de l’exploitation peuvent survenir n’importe quand, avec une légère préférence pour la nuit et les week-ends. Quoi qu’il en soit, toutes les équipes donnent le meilleur d’elles-mêmes en tout temps. Pour parachever l’arrêt technique du week-end dernier, l’équipe chargée de la protection des machines et de l’intégrité électrique a travaillé jusqu’à cinq heures samedi matin et les équipes responsables du contrôle et du cadencement étaient au poste dimanche entre deux heures et six heures du matin pour gérer les effets d’une simple seconde intercalaire. Enfin, rien ne serait possible dans le complexe d’accélérateurs sans la contribution d’une équipe d’opérateurs talentueux, intelligents et plutôt beaux, et qui ont bien sûr dû développer un sens de l’humour très pointu. Le LHC a repris ses opérations le vendredi 29 juin, après un arrêt technique de cinq jours. Pour obtenir des informations en temps réel sur le fonctionnement de la machine, consultez la page <a href="http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php" target="_blank">LHC 1</a>. NO CERN Bulletin noicon ONLINE 4 28/2012 CERN Bulletin 4 29/2012 CERN Bulletin bulletin-editors@cern.ch student.journalist@cern.ch Bulletin-Editors@cern.ch https://repository.cern/legacy/record/1456545 BULLETINNEWS MIGRATED 1090841 SzGeCERN 20080225140903.0 eng PRESSCUT-H-2008-107 Strange science takes time 2008 A copy of this item is available from the Press Office The late astronomer Carl Sagan popularized the saying that "extraordinary claims require extraordinary evidence," in reference to reports of alien visitations. Generating low-cost commercial fusion power, isolating antimatter and tracing reverse-time causality aren't as far out there as UFOs, but a similar rule might well apply: Extraordinary science requires extraordinary effort. With that in mind, here's a progress report on three extraordinary science projects that have popped up in the news... SzGeCERN Other Subjects CERN Cramer, John CERN Reverse-time CERN ITER- International Thermonuclear Experimental Reactor PRESS CUTTING Internet 9 January 2008 COSMIC LOG 2008 h 200809 17 20080225 1409 CER01 20080225 PUBLIC 002745466CER CUTTING