13 kA LHC bus bar structure tree

The document includes a list of the LHC bus bars and their reference drawings per magnet type, and specifically: • The Main Bending magnets, also called MB, • The Magnet Quadrupoles, the MQs, • The quadrupoles in the LHC Dispersion Sections, MQDS, • The quadrupoles in the Matching Sections, named MQMs, • The Cryogenic Connections (CC) and • The DFB shuffling modules

La gestion de la fonction maintenance

Le présent article a pour objet d'analyser la fonction maintenance au sein de la division ST. Seront d'abord évoqués, les principaux facteurs qui ont marqué ladite fonction tels que sa décentralisation au niveau de chaque groupe, organisé par spécialité, et l'externalisation des activités jugées non stratégiques. En rapprochant la fonction maintenance de la fonction études et travaux, la décentralisation a sans doute permis de développer, par spécialité, un niveau de compétence accru. La sous-traitance de plus en plus importante de nos activités et les recrutements à un niveau plus élevé ont permis de faire face aux diminutions de personnel CERN. Cependant, ces aspects positifs s'accompagnent d'effets pervers tels que le manque de communication entre les services de maintenance de chaque spécialité, la disparité des approches dans la façon de gérer les activités et d'organiser le travail, et une difficulté à analyser globalement les performances des contractants. Ces différentes raisons ont poussé le management de la division à se doter d'une coordination centrale de cette fonction par l'intermédiaire d'un groupe de travail constitué par les responsables d'opération. Le rôle à jouer par ces derniers et les actions qu'ils ont entreprises seront examinées. Les auteurs voudraient, dans cet article, montrer à quel point la création d'une fonction centrale de coordination de la maintenance permet d'éviter les différences constatées et faciliter une sérieuse optimisation technique et économique de la fonction

A new approach for water treatment

A quantity of up to 4000 m3/h of water is used at CERN for cooling purposes: experiments, magnets and radio frequency cavities are refrigerated by closed circuits filled with deionized water; other utilities, such as air-conditioning, use chilled/hot water, also in closed circuits. All these methods all employ a cold source, the primary supply of water, coming from the cooling towers. About 500 kCHF are spent every year on water treatment in order to keep the water within these networks in operational conditions. In the line of further rationalization of resources, the next generation of contracts with the water treatment industry will aim for improved performance and better monitoring of quality related parameters in this context. The author will provide a concise report based upon an examination of the state of the installations and of the philosophy followed up until now for water treatment. Furthermore, he/she will propose a new approach from both a technical and contractual point of view, in preparation for a call for tender which is foreseen to be issued during 1999. As the water tower circuits (primary water) are quantitatively dominating, the technical discussion will concentrate mainly on problems linked with these networks

The LHC experiments as seen from the Technical Sector

Since the beginning of the collaboration between the ST division and the LHC experiments, already in 1998, the technical sector has provided different structures for the support of the experiments, aiming to coordinate all the activities, which traditionally belong in the technical sector's mandate, like civil engineering and structures, cooling and ventilation, cranes and transport, electricity, gas, etc. A picture of the last year's activity, mainly concentrated on the ATLAS and CMS experiments, shows how the synergies between project managers, staff involved and group structures can strongly improve the service level in the technical domain. This closer collaboration has facilitated the development of further ties linked to the competence available in the groups, and of great interest to the experiments. The steady rise in demand confirms that the choice, made by the experiments, confirms that the technical sector support is a real need in this are

Molecules in the transition disk orbiting T Cha

We seek to establish the presence and properties of gas in the circumstellar disk orbiting T Cha, a nearby (d~110 pc), relatively evolved (age ~5-7 Myr) yet actively accreting 1.5 Msun T Tauri star. We used the APEX 12 m radiotelescope to search for submillimeter molecular emission from the T Cha disk, and we reanalyzed archival XMM-Newton spectroscopy of T Cha to ascertain the intervening absorption due to disk gas along the line of sight to the star (N_H). We detected submillimeter rotational transitions of 12CO, 13CO, HCN, CN and HCO+ from the T Cha disk. The 12CO line appears to display a double-peaked line profile indicative of Keplerian rotation. Analysis of the CO emission line data indicates that the disk around T Cha has a mass (M_disk,H_2 = 80 M_earth) similar to, but more compact (R_disk, CO~80 AU) than, other nearby, evolved molecular disks (e.g. V4046 Sgr, TW Hya, MP Mus) in which cold molecular gas has been previously detected. The HCO+/13CO and HCN/13CO, line ratios measured for T Cha appear similar to those of other evolved circumstellar disks (i.e. TW Hya and V4046 Sgr), while the CN/13CO ratio appears somewhat weaker. Analysis of the XMM-Newton data shows that the atomic absorption $N_H$ toward T Cha is 1-2 orders of magnitude larger than toward the other nearby T Tauri with evolved disks. Furthermore, the ratio between atomic absorption and optical extinction N_H/A_V toward T Cha is higher than the typical value observed for the interstellar medium and young stellar objects in the Orion Nebula Cluster. This may suggest that the fraction of metals in the disk gas is higher than in the interstellar medium. Our results confirm that pre-main sequence stars older than ~5 Myr, when accreting, retain cold molecular disks, and that those relatively evolved disks display similar physical and chemical properties.Comment: Accepted for publication on A&

Year 2000 Performance Report

The mandate of the ST/CV-OP unit consists in the operation and maintenance of the cooling systems and air conditioning installations for the PS accelerator complex, the SPS and LEP machines as well as the heating plants and all CERN pumping stations. This paper intends to provide the performance report related to the last twelve months of activity of the operation unit. The role of the Computed Aided Maintenance and the evolution of a set of performance indicators during last three years will also be presented. A brief analysis of the data and a comment related to opportunity represented by the LEP-LHC transition will follow. In addition the author will try to give in figures a more specific idea of the operation environment, how this function evolves in numbers and which are, in his opinion, the improvement axes and the eventual risks

A pulsational distance to Omega Centauri based on Near-Infrared Period-Luminosity relations of RR Lyrae stars

We present new Near-Infrared (J,K) magnitudes for 114 RR Lyrae stars in the globular cluster Omega Cen (NGC 5139) which we combine with data from the literature to construct a sample of 180 RR Lyrae stars with J and K mean magnitudes on a common photometric system. This is presently the largest such sample in any stellar system. We also present updated predictions for J,K-band Period-Luminosity relations for both fundamental and first-overtone RR Lyrae stars, based on synthetic horizontal branch models with metal abundance ranging from Z=0.0001 to Z=0.004. By adopting for the Omega Cen variables with measured metal abundances an alpha-element enhancement of a factor of 3 (about 0.5 dex) with respect to iron we find a true distance modulus of 13.70 (with a random error of 0.06 and a systematic error of 0.06), corresponding to a distance d=5.5 Kpc (with both random and systematic errors equal to 0.03 Kpc). Our estimate is in excellent agreement with the distance inferred for the eclipsing binary OGLEGC-17, but differ significantly from the recent distance estimates based on cluster dynamics and on high amplitude Delta Scuti stars.Comment: 24 pages, 7 figures, accepted for publication on The Astrophysical Journa

Activin and TGFβ use diverging mitogenic signaling in advanced colon cancer.

BackgroundUnderstanding cell signaling pathways that contribute to metastatic colon cancer is critical to risk stratification in the era of personalized therapeutics. Here, we dissect the unique involvement of mitogenic pathways in a TGFβ or activin-induced metastatic phenotype of colon cancer.MethodMitogenic signaling/growth factor receptor status and p21 localization were correlated in primary colon cancers and intestinal tumors from either AOM/DSS treated ACVR2A (activin receptor 2) -/- or wild type mice. Colon cancer cell lines (+/- SMAD4) were interrogated for ligand-induced PI3K and MEK/ERK pathway activation and downstream protein/phospho-isoform expression/association after knockdown and pharmacologic inhibition of pathway members. EMT was assessed using epithelial/mesenchymal markers and migration assays.ResultsIn primary colon cancers, loss of nuclear p21 correlated with upstream activation of activin/PI3K while nuclear p21 expression was associated with TGFβ/MEK/ERK pathway activation. Activin, but not TGFβ, led to PI3K activation via interaction of ACVR1B and p85 independent of SMAD4, resulting in p21 downregulation. In contrast, TGFβ increased p21 via MEK/ERK pathway through a SMAD4-dependent mechanism. While activin induced EMT via PI3K, TGFβ induced EMT via MEK/ERK activation. In vivo, loss of ACVR2A resulted in loss of pAkt, consistent with activin-dependent PI3K signaling.ConclusionAlthough activin and TGFβ share growth suppressive SMAD signaling in colon cancer, they diverge in their SMAD4-independent pro-migratory signaling utilizing distinct mitogenic signaling pathways that affect EMT. p21 localization in colon cancer may determine a dominant activin versus TGFβ ligand signaling phenotype warranting further validation as a therapeutic biomarker prior to targeting TGFβ family receptors

Hubble Space Telescope Observations of an Outer Field in Omega Centauri: A Definitive Helium Abundance

We revisit the problem of the split main sequence (MS) of the globular cluster omega Centauri, and report the results of two-epoch Hubble Space Telescope observations of an outer field, for which proper motions give us a pure sample of cluster members, and an improved separation of the two branches of the main sequence. Using a new set of stellar models covering a grid of values of helium and metallicity, we find that the best possible estimate of the helium abundance of the bluer branch of the MS is Y = 0.39 +/- 0.02. For the cluster center we apply new techniques to old observations: we use indices of photometric quality to select a high-quality sample of stars, which we also correct for differential reddening. We then superpose the color-magnitude diagram of the outer field on that of the cluster center, and suggest a connection of the bluer branch of the MS with one of the more prominent among the many sequences in the subgiant region. We also report a group of undoubted cluster members that are well to the red of the lower MS.Comment: 26 pages, 10 figures (4 in low resolution. AJ accepted on March 21, 201