Kowalczyk, P Poncet, Alain Sacré, P Skoczen, Blazej Thermal Performance of the LHC External Auxiliary Bus-Bar Tube: Mathematical Modelling The Large Hadron Collider (LHC) externally routed auxiliary bus-bar tube (EAB) will house the electrical feeders of the LHC short straight section (SSS) correcting magnets. The superconducting wires w ill be contained in a stainless steel tube and immersed in a quasi-static helium bath. The EAB thermal performance during the cooling of the magnets down to the operating temperature of 1.9 K is studi ed. A 3-d finite element thermal model of the EAB during a cooling process from 293 K to 4.5 K is described. The semi-analytical model of the EAB cool-down from 4.5 K to 1.9 K is also presented. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-204; http://cds.cern.ch/record/361130/files/lhc-project-report-204.pdf; http://cds.cern.ch/record/361130/files/lhc-project-report-204.ps.gz;

Imported from Invenio. Denz, R Gerstenberg, H Hagedorn, Dietrich Irradiation Tests at Cryogenic Temperatures on Diffusion Type Diodes for the LHC Superconducting Magnet Protection Within the framework of the LHC magnet protection system, the irradiation hardness of high current by-pass diodes is subject to examination. The relocation of these diodes and recent calculations give rather low irradiation levels for the position of the diodes. This offers the possibility to replace the originally foreseen epitaxial type diodes by diffusion type diodes. Therefore, different types of 75mm diffusion diodes were submitted to an irradiation test program. One part of the experiments was performed in the Munich Research Reactor. Further irradiation tests were carried out in the northern fixed target area of the SPS accelerator at CERN. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-267; http://cds.cern.ch/record/379700/files/lhc-project-report-267.pdf; http://cds.cern.ch/record/379700/files/lhc-project-report-267.ps.gz;

Imported from Invenio. Denz, R Hagedorn, Dietrich Experimental Analysis and Modeling of the Electrical and Thermal Transients of the Diode-By-pass for the LHC- Magnet Protection at Cryogenic Temperatures For the protection of the LHC superconducting lattice magnets cold bypass diodes will be installed inside the magnet cryostat, subjecting them to superfluid helium temperatures and radiation. During a magnet quench, the power generated in the diode must be dissipated in the adjacent heat sinks of copper that are part of the diode package. Results from endurance tests on the diode package are presented. A simple thermo-electric model has been developed to simulate the thermal and electrical transients in the diode package during the endurance pulse. Simulation results are in good agreement with the measured temperatures. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-268; http://cds.cern.ch/record/379597/files/lhc-project-report-268.pdf; http://cds.cern.ch/record/379597/files/lhc-project-report-268.ps.gz;

Imported from Invenio. Barranco-Luque, M Cherfaoui, M Hervé, C Margaroli, C Sergo, V Quality Testing of Gaseous Helium Pressure Vessels by Acoustic Emission The resistance of pressure equipment is currently tested, before commissioning or at periodic maintenance, by means of normal pressure tests. Defects occurring inside materials during the execution of these tests or not seen by usual non-destructive techniques can remain as undetected potential sources of failure . The acoustic emission (AE) technique can detect and monitor the evolution of such failures. Industrial-size helium cryogenic systems employ cryogens often stored in gaseous form under pressure at ambient temperature. Standard initial and periodic pressure testing imposes operational constraints which other complementary testing methods, such as AE, could significantly alleviate. Recent reception testing of 250 m3 GHe storage vessels with a design pressure of 2.2 MPa for the LEP and LHC cryogenic systems has implemented AE with the above-mentioned aims. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-218; http://cds.cern.ch/record/369613/files/lhc-project-report-218.pdf; http://cds.cern.ch/record/369613/files/lhc-project-report-218.ps.gz;

Imported from Invenio. Bremer, J Cambon, A Chalifour, M Haug, F Passardi, Giorgio Tischhauser, Johann Cryogenic System for the Test Facilities of the ATLAS Liquid Argon Calorimeter Modules To perform cold tests on the different modules of the ATLAS liquid argon calorimeter, a cryogenic system has been constructed and is now operated at the CERN North Experimental Area. Three different test cryostats will house the modules, which can also be exposed to particle beams for calibration purposes. The three cryostats share a common liquid argon and liquid nitrogen distribution system. The system is rather complex since it has to allow operations of the three cryostats at the same time. Liquid nitrogen is used as cold source for both the cool-down of the cryostats and for normal operation of the cryostats filled with liquid argon. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-234; http://cds.cern.ch/record/367264/files/367264.zip; http://cds.cern.ch/record/367264/files/lhc-project-report-234.pdf; http://cds.cern.ch/record/367264/files/lhc-project-report-234.ps.gz;

Imported from Invenio. Bouyaya, A Policella, C Rieubland, Jean Michel Vandoni, Giovanna A Microcryostat for Refrigeration at 1.8 K A microcryostat has been developed in the Central Cryogenic Laboratory at CERN with the purpose of cooling a prototype beam loss monitor for the LHC, based on bolometry at 1.8 K. Its characteristics a re the very compact volume (some cm3 LHe) ensuring short cooldown-warmup times, and its low heat losses (~ 8 mW). The cryostat can be mounted on top of a small dewar through a rigid straight transfer line for continuous feeding. eng 1.8; 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-231; http://cds.cern.ch/record/365436/files/lhc-project-report-231.pdf; http://cds.cern.ch/record/365436/files/lhc-project-report-231.ps.gz;

Imported from Invenio. Blin, M Ferlin, G Gauss, P Policella, C Rieubland, Jean Michel Vandoni, Giovanna Cryogenic R&D at the CERN Central Cryogenic Laboratory The Central Cryogenic Laboratory operates since many years at CERN in the framework of cryogenic R&D for accelerators and experiments. The laboratory hosts several experimental posts for small cryogen ic tests, all implemented with pumping facility for GHe and vacuum, and is equipped with a He liquefier producing 6.105 l/year, which is distributed in dewars. Tests include thermomechanical qualifica tion of structural materials, cryogenic and vacuum qualification of prototypes, evaluation of thermal losses of components. Some of the most relevant results obtained at the laboratory in the last yea rs are outlined in this paper. eng 1998

http://documents.cern.ch/cgi-bin/setlink?base=generic&categ=public&id=cer-000290518; http://cds.cern.ch/record/365435/files/cer-000290518.pdf;

Imported from Invenio. Dauvergne, J P Vandoni, Giovanna Backstreaming of Impurity Gas Through a Leak in Pressurized Vessel The presence of a leak in a vessel containing pure gas can induce the contamination by atmospheric gas diffusing into the vessel. In order to avoid this, a gas which has to be kept pure also in presen ce of a leak is usually pressurized, to reduce the flow of contaminating gas through the leak owing to the molecular drag by the outstreaming pure gas. In this paper, a simple model calculation of ba ckstreaming based on the solution of the diffusion + drag equation in cylindrical coordinates is presented. It is shown that both the pressure difference and the dimension of the leak are critical in determining the contaminating flow, a maximum in the backstreaming flow appearing when the drag velocity of the outstreaming gas equals the diffusion velocity. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-229; http://cds.cern.ch/record/365434/files/lhc-project-report-229.pdf; http://cds.cern.ch/record/365434/files/lhc-project-report-229.ps.gz;

Imported from Invenio. Camacho, D Chevassus, S Policella, C Rieubland, Jean Michel Vandoni, Giovanna Van Weelderen, R Thermal Characterization of the HeII LHC Heat Exchanger Tube The LHC magnet cooling scheme is based on a HeII bayonet heat exchanger, which acts as a quasi isothermal heat sink. In order to assess the thermal performance of the oxygen free, annealed/cold worked copper tube, measurements of the total thermal conductance of the tube were performed in a laboratory set-up. This paper describes the experimental technique, which permits to separate the contributio n of the Kapitza interface resistance from the total transverse conductance. The influence of the surface treatment on the Kapitza resistance is also discussed. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-232; http://cds.cern.ch/record/365293/files/lhc-project-report-232.pdf; http://cds.cern.ch/record/365293/files/lhc-project-report-232.ps.gz;

Imported from Invenio. Barth, K Dauvergne, J P Delikaris, D Delruelle, N Ferlin, G Passardi, Giorgio Rieubland, Jean Michel New cryogenic facilities for testing superconducting equipments for the CERN Large Hadron Collider CERN's major project, the Large Hadron Collider (LHC), has moved to an implementation phase with machine construction to be completed by 2005. To achieve the design proton-proton centre of mass energy of 14 TeV in the given 27 km circumference LEP tunnel, the LHC will make an extensive use of high-field superconducting magnets using Nb-Ti filament operated at 1.9 K. In order to test, on the one han d, the superconducting cables of the magnets and, on the other hand, the expected performance of several of these magnets assembled in a string representing the lattice period of the machine (107 m lo ng), CERN has installed new cryogenic test facilities. The paper briefly describes these new facilities with all their associated equipments. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-228; http://cds.cern.ch/record/365292/files/lhc-project-report-228.pdf; http://cds.cern.ch/record/365292/files/lhc-project-report-228.ps.gz;

Imported from Invenio. Rodríguez-Mateos, F Schmidt, R Serio, L Thermo-hydraulic Quench Propagation at the LHC Superconducting Magnet String The superconducting magnets of the LHC are protected by heaters and cold by-pass diodes. If a magnet quenches, the heaters on this magnet are fired and the magnet chain is de-excited in about two minu tes by opening dump switches in parallel to a resistor. During the time required for the discharge, adjacent magnets might quench due to thermo-hydraulic propagation in the helium bath and/or heat con duction via the bus bar. The number of quenching magnets depends on the mechanisms for the propagation. In this paper we report on quench propagation experiments from a dipole magnet to an adjacent ma gnet. The mechanism for the propagation is hot helium gas expelled from the first quenching magnet. The propagation changes with the pressure opening settings of the quench relief valves. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-222; http://cds.cern.ch/record/365291/files/lhc-project-report-222.pdf; http://cds.cern.ch/record/365291/files/lhc-project-report-222.ps.gz;

Imported from Invenio. Byrns, R A Huang, Y Kerby, J S Lebrun, P Morrison, L Nicol, T H Peterson, T Trant, R Van Weelderen, R Zbasnik, J The Cryogenics of the LHC Interaction Region Final Focus Superconducting Magnets The LHC interaction region final focus magnets will include four superconducting quadrupoles cooled with pressurized, static superfluid helium at 1.9 K. The heat absorbed in pressurized He II, which m ay be more than 10 Watts per meter due to dynamic heating from the particle beam halo, will be transported to saturated He II at 1.8 K and removed by the 16 mbar vapor. This paper discusses the concep tual design for the cryogenics of the interaction region final focus superconducting magnets and the integration of this magnet system into the overall LHC cryogenic system. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-219; http://cds.cern.ch/record/365289/files/lhc-project-report-219.pdf; http://cds.cern.ch/record/365289/files/lhc-project-report-219.ps.gz;

Imported from Invenio. Rousset, B Gauthier, A Jäger, B Van Weelderen, R Weisend, J G Hydraulic Behaviour of He II in Stratified Counter-Current Two-Phase Flow Future large devices using superconducting magnets or RF cavities (e.g. LHC or TESLA) need He II two-phase flow for cooling. The research carried out into counter-current superfluid two-phase flow was the continuation of work on co-current flow and benefited from all the knowledge acquired both experimentally and theoretically. Experiments were conducted on two different pipe diameters (40 and 65 m m I.D. tube) for slopes ranging between 0 and 2%, and for temperatures ranging between 1.8 and 2 K. This paper introduces the theoretical model, describes the tests, and provides a critical review of the results obtained in He II counter current two-phase flow. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-217; http://cds.cern.ch/record/365287/files/lhc-project-report-217.pdf; http://cds.cern.ch/record/365287/files/lhc-project-report-217.ps.gz;

Imported from Invenio. Benda, V Zilbert, O Current Feedthroughs for Superconducting Magnets Operating Below 2 K For superconducting magnets working in superfluid helium, a thermal and pressure barrier between liquid helium baths at different temperatures, so called "lambda plate", is required. Bus bars connecte d to current leads of magnets to be powered, pass through current feedthroughs. These feedthroughs have to stand high pressure, thermal shock, high voltage, and mechanical stresses, must be leak tight and introduce minimum heat inleak. This article describes a possible solution. Three prototypes were built and measured. Design of this feedthrough and preliminary results are presented. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-216; http://cds.cern.ch/record/365286/files/lhc-project-report-216.pdf; http://cds.cern.ch/record/365286/files/lhc-project-report-216.ps.gz;

Imported from Invenio. Chorowski, M Skoczen, Blazej Thermo-mechanical Analysis of Cold Helium Injection into Gas Storage Tanks made of Carbon Steel Following Resistive Transition of the LHC Magnets A resistive transition (quench) of the LHC sector magnets will be followed by cold helium venting to a quench buffer volume of 2000 m3 at ambient temperature. The volume will be composed of eight medi um-pressure (2 MPa) gas storage tanks made of carbon steel, which constrains the temperature of the wall to be higher than -50oC (223 K). The aim of the analysis is the assessment of a possible spot c ooling intensity and thermo-mechanical stresses in the tank wall following helium injection. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-215; http://cds.cern.ch/record/365282/files/lhc-project-report-215.pdf; http://cds.cern.ch/record/365282/files/lhc-project-report-215.ps.gz;

Imported from Invenio. Lebrun, P Riddone, G Tavian, L Wagner, U Cooldown and Warmup Studies for the Large Hadron Collider The Large Hadron Collider (LHC), currently under construction at CERN, will make use of superconducting magnets operating in superfluid helium below 2 K. The LHC ring is divided in 8 sectors, each of them cooled by a refrigerator of 18 kW at 4.5 K equivalent cooling power. For the cooldown and warmup of a 3.3 km long LHC sector, the flow available above 80 K per refrigerator is 770 g/s and the cor responding capacity is 600 kW. This paper presents the results of cooldown and warmup simulations, as concerns time delays, temperature difference across magnets, available power and flow-rates, and estimates of energy and liquid nitrogen consumption. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-214; http://cds.cern.ch/record/365281/files/lhc-project-report-214.pdf; http://cds.cern.ch/record/365281/files/lhc-project-report-214.ps.gz;

Imported from Invenio. Flemsæter, B Blanco-Viñuela, E Casas-Cubillos, J De Prada-Moraga, C Saelid, S Applying Advanced Control Techniques for Temperature Regulation of the LHC Superconducting Magnets The temperature of the superconducting magnets for the future LHC accelerator is a control parameter with strict operating constraints imposed by (a) the maximum temperature at which the magnets can o perate, (b) the cooling capacity of the cryogenic system, (c) the variability of applied heat loads and (d) the accuracy of the instrumentation. A temperature regulation with narrow control band can i n principle be achieved by implementing a Model Predictive Control (MPC)-type controller. For this purpose, and for investigating the behaviour of the cooling system, a simulation program has been dev eloped. A prototype MPC controller has been installed and completed its first run. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-221; http://cds.cern.ch/record/364771/files/lhc-project-report-221.pdf; http://cds.cern.ch/record/364771/files/lhc-project-report-221.ps.gz;

Imported from Invenio. Bézaguet, Alain-Arthur Lebrun, P Tavian, L Performance Assessment of Industrial Prototype Cryogenic Helium Compressors for the Large Hadron Collider In order to develop the technology of large-capacity refrigeration at superfluid helium temperature, essential for the LHC project, CERN has procured from industry three prototype single-stage hydrody namic cryogenic helium compressors, based on different construction choices, and tested them in the laboratory. After recalling the common functional specification, as well as the main design features of the three machines, we present comparative performance results, and draw conclusions as concerns future full-scale machines for the LHC. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-213; http://cds.cern.ch/record/364735/files/lhc-project-report-213.pdf; http://cds.cern.ch/record/364735/files/lhc-project-report-213.ps.gz;

Imported from Invenio. Hatchadourian, E Lebrun, P Tavian, L Supercritical Helium Cooling of the LHC Beam Screens The cold mass of the LHC superconducting magnets, operating in pressurised superfluid helium at 1.9 K, must be shielded from the dynamic heat loads induced by the circulating particle beams, by means of beam screens maintained at higher temperature. The beam screens are cooled between 5 and 20 K by forced flow of weakly supercritical helium, a solution which avoids two-phase flow in the long, narr ow cooling channels, but still presents a potential risk of thermohydraulic instabilities. This problem has been studied by theoretical modelling and experiments performed on a full-scale dedicated te st loop. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-212; http://cds.cern.ch/record/364733/files/lhc-project-report-212.pdf; http://cds.cern.ch/record/364733/files/lhc-project-report-212.ps.gz;

Imported from Invenio. Lebrun, P Advances in Cryogenics at the Large Hadron Collider After a decade of intensive R&D in the key technologies of high-field superconducting accelerator magnets and superfluid helium cryogenics, the Large Hadron Collider (LHC) has now fully entered its co nstruction phase, with the adjudication of major procurement contracts to industry. As concerns cryogenic engineering, this R&D program has resulted in significant developments in several fields, amon g which thermo-hydraulics of two-phase saturated superfluid helium, efficient cycles and machinery for large-capacity refrigeration at 1.8 K, insulation techniques for series-produced cryostats and mu lti-kilometre long distribution lines, large-current leads using high-temperature superconductors, industrial precision thermometry below 4 K, and novel control techniques applied to strongly non-line ar processes. We review the most salient advances in these domains. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-211; http://cds.cern.ch/record/364732/files/lhc-project-report-211.pdf; http://cds.cern.ch/record/364732/files/lhc-project-report-211.ps.gz;

Imported from Invenio. Casas-Cubillos, J Provenaz, P Serio, L Suraci, A Van Weelderen, R Operation, Testing and Long Term Behaviour of the LHC Test String Cryogenic System Since the end of 1994 we have been operating a prototype half-cell of the machine lattice, accumulating more than 10,000 hours at superfluid helium temperatures and recovering from 150, mainly provoke d, magnet resistive transitions. The system has confirmed the validity of the basic design choices of the LHC cryogenic system. Furthermore, extensive testing on the response of the system to current ramp and discharge, and to magnet resistive transition, has provided sufficient information to enable a simplification of the cryogenic scheme that fulfils the LHC requirements. We report on the cryog enic operation, testing and long-term behaviour of the LHC Test String during the last 4 years of operation. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-210; http://cds.cern.ch/record/364731/files/lhc-project-report-210.pdf; http://cds.cern.ch/record/364731/files/lhc-project-report-210.ps.gz;

Imported from Invenio. Amand, J F Casas-Cubillos, J Junquera, T Thermeau, J P Neutron Irradiation Tests in Superfluid Helium of LHC Cryogenic Thermometers For control and monitoring purposes, about 10,000 individually calibrated cryogenic temperature sensors will be installed along the 26.7 km LHC. In order to reduce maintenance constraints these sensor s should be as immune as possible to the high neutron fluence environment. For selecting the sensor to be used, a radiation hardness evaluation program at cryogenic conditions is being performed in an irradiation vault of the ISN SARA Cyclotron (Grenoble, France). The set-up is capable of simulating the whole life of a LHC thermometer: same total neutron dose (1015 n.cm-2), irradiation at low tempe rature (1.8 K) and thermal cycles. Bath temperature and sensor resistance are monitored on-line. This paper presents the latest results of this program. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-209; http://cds.cern.ch/record/364729/files/lhc-project-report-209.pdf; http://cds.cern.ch/record/364729/files/lhc-project-report-209.ps.gz;

Imported from Invenio. Darve, C Vandoni, Giovanna Thermal Performance of Insulating Cryogenic Pin Spacers Following the proposal to introduce an actively cooled radiation screen (5-10 K) for the LHC machine, the design of the LHC cryostat foresees the need for spacers between the cold mass and the radiati on screen. The thermal impedance of the chosen material should be very high and the shape selected to withstrand the contact stress due to the displacements induced by the coll-down and warm-up transi ent. A cryogenic experiment dedicated to studying the thermal behaviour of several proposed spacers was performed at the cryogenics laboratory of CERN before choosing the one to be used for further i nvestigation on the LHC full-scale Cryostat Thermal Model [1] [2]. This paper describes a quantitative analysis leading to the choice of the spacer. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-220; http://cds.cern.ch/record/361966/files/lhc-project-report-220.pdf; http://cds.cern.ch/record/361966/files/lhc-project-report-220.ps.gz;

Imported from Invenio. Skoczen, Blazej Mechanical stability of the LHC dipole-dipole 50-75K thermal shield interconnect: "floating" expansion joint concept The LHC dipole cryostats are equipped with thermal shields carrying super-insulation. A cold helium transfer line equipped with expansion joints is integrated into the shield carrying trays (aluminium profiles supported on three composite feet). The stainless steel (316 L) expansion joints compensate for thermal contraction/expansion of the aluminium panels as well as for their misalignment. Design of the LHC thermal shield interconnect is based on the "floating" expansion joint concept (distance between the supports is of around 5 m). The present paper is dedicated to the analysis of mechanical stability of this large span system working at room and at cryogenic temperatures. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=LHC-PROJECT-REPORT-207; http://cds.cern.ch/record/361677/files/lhc-project-report-207.pdf;

Imported from Invenio. Bremer, J Cundy, Donald C Dauvergne, J P Gonidec, A Kesseler, G Kubischta, Werner Linser, G Schinzel, D Taureg, Hans Wertelaers, Piet The liquid krypton calorimeter cryogenics for the NA48 experiment The NA48 cryogenic system has to provide stable thermal conditions (120 K) in a 9000 liter liquid krypton calorimeter, and has to ensure safe and loss free storage of the liquid during idle periods. Direct cooling of the krypton by nitrogen is used in emergency cases, while an intermediate cooler, containing saturated liquid argon at around 10 bar (117 K) is used under normal operation conditions when high thermal stability is needed. The krypton pressure is, during data taking, regulated to a value of (1.05 $\pm$ 0.01) bar for a period of about 8 months of continuous operation of the calorimeter. eng 1998

http://preprints.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhc-98-007; http://cds.cern.ch/record/367870/files/lhc-98-007.pdf; http://cds.cern.ch/record/367870/files/lhc-98-007.ps.gz;

Imported from Invenio. Evans, Lyndon R Lebrun, P Progress in construction of the LHC The Large Hadron Collider (LHC) project, approved by the CERN Council in December 1994, has now fully entered its construction phase, with the detailed technical definition of the major systems, and the adjudication of a number of large procurement contracts. We first recall the main features and characteristics of the LHC, report on the advances in definition of the layout and optics as well as on preparation of the injector complex, and review recent progress in the key technical systems of the main ring: magnets, cryogenics and vacuum, as well as civil construction, which has started following acceptance by authorities in the Host States. eng 1998

http://cds.cern.ch/record/367978/files/lhc-project-report-239.pdf; http://cds.cern.ch/record/367978/files/lhc-project-report-239.ps.gz; http://cds.cern.ch/record/367978/files/HEACC98_257-261.pdf;

Imported from Invenio.