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

Value of information in the binary case and confusion matrix

The simplest Bayesian system used to illustrate ideas of probability theory is a coin and a boolean utility function. To illustrate ideas of hypothesis testing, estimation or optimal control, one needs to use at least two coins and a confusion matrix accounting for the utilities of four possible outcomes. Here we use such a system to illustrate the main ideas of Stratonovich’s value of information (VoI) theory in the context of a financial time-series forecast. We demonstrate how VoI can provide a theoretical upper bound on the accuracy of the forecasts facilitating the analysis and optimization of models

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

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

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&