AIP Conf. Proc. AIP Conf. Proc. The Common Cryogenic Test Facility for the Atlas Barrel and End-Cap Toroid Magnet Delruelle N Haug F Junker S Passardi Giorgio Pengo R Pirotte O 2004 710 249 256 The large ATLAS toroidal superconducting magnet made of the Barrel and two End-Caps needs extensive testing at the surface of the individual components prior to their final assembly into the underground cavern of LHC. A cryogenic test facility specifically designed for cooling sequentially the eight coils making the Barrel Toroid (BT) has been fully commissioned and is now ready for final acceptance of these magnets. This facility, originally designed for testing individually the 46 tons BT coils, will be upgraded to allow the acceptance tests of the two End-Caps, each of them having a 160 tons cold mass. The integrated system mainly comprises a 1.2 kW@4.5 K refrigerator, a 10 kW liquid-nitrogen precooler, two cryostats housing liquid helium centrifugal pumps of respectively 80 g/s and 600 g/s nominal flow and specific instrumentation to measure the thermal performances of the magnets. This paper describes the overall facility with particular emphasis to the cryogenic features adopted to match the specific requirements of the magnets in the various operating scenarios. research-article

The Design of Cold to Warm Transitions of the LHC Knaster J R CERN Jenninger B Ramos D Ratcliffe G Veness R J M 2004 The Large Hadron Collider (LHC), the next accelerator being constructed on the CERN site, will accelerate and collide 7 TeV protons and heavier ions up to lead. More than 1700 cryomagnets working at 1.9 or 4.5 k will form part of the magnetic lattice of the LHC. The beam pipe passage from cryogenic temperatures to room temperature zones will be achieved by 200 cold to warm transitions (CWTs). The CWTs will compensate for longitudinal and transversal displacements between beam screens and cold bores, ensuring vacuum continuity without limiting the aperture for the beam. The transverse impedance contribution is kept below the assigned total budget of 1 MO/m by means of a 4 µm thick Cu coating that also minimises the dynamic heat load through image currents. Tests have been performed that confirm that the static heat load per CWT to the cryomagnets remains below 2.5 W, hence validating the design. research-article

The Management of Cryogens at CERN Barth K Passardi Giorgio Serio L Tavian L Delikaris D 2005 CERN is a large user of industrially procured cryogens essentially liquid helium and nitrogen. Recent contracts have been placed by the Organization for the delivery of quantities up to 280 tons of liquid helium over four years and up to 50000 tons of liquid nitrogen over three years. Main users are the very large cryogenic system of the LHC accelerator complex, the physics experiments using superconducting magnets and liquefied gases and all the related test facilities whether industrial or laboratory scale. With the commissioning of LHC, the need of cryogens at CERN will considerably increase and the procurement policy must be adapted accordingly. In this paper, we discuss procurement strategy for liquid helium and nitrogen, including delivery rates, distribution methods and adopted safety standards. Global turnover, on site re-liquefaction capacity, operational consumption, accidental losses, purification means and storage capacity will be described. Finally, the short to medium term evolution of the Organization’s requirements will be reviewed. research-article

Thermal Performance of the Supporting System for the Large Hadron Collider (LHC) Superconducting Magnets Castoldi M Pangallo M Parma Vittorio Vandoni Giovanna 1999 The LHC collider will be composed of approximately 1700 main ring superconducting magnets cooled to 1.9 K in pressurised superfluid helium and supported within their cryostats on low heat in-leak column-type supports. The precise positioning of the heavy magnets and the stringent thermal budgets imposed by the machine cryogenic system, require a sound thermo-mechanical design of the support system. Each support is composed of a main tubular thin-walled structure in glass-fibre reinforced epoxy resin, with its top part interfaced to the magnet at 1.9 K and its bottom part mounted onto the cryostat vacuum vessel at 293 K. In order to reduce the conduction heat in-leak at 1.9 K, each support mounts two heat intercepts at intermediate locations on the column, both actively cooled by cryogenic lines carrying helium gas at 4.5-10 K and 50-65 K. The need to assess the thermal performance of the supports has lead to setting up a dedicated test set-up for precision heat load measurements on prototype supports. This paper presents the thermal design of the support system of the LHC arc magnets. The results of the thermal tests of a prototype support made in industry are illustrated and discussed. A mathematical model has been set up and refined by the comparison with test results, with the scope of extrapolating the observed thermal performance to different geometrical and material parameters. Finally, the calculated estimate of the heat load budgets of the support system and their contribution to the total cryogenic budget for an LHC arc are presented. PREPRINT

Thermal Conductivity of Structural Glass/Fibre Epoxy Composite as a Function of Fibre Orientation Cugnet D Hauviller Claude Kuijper A Parma Vittorio Vandoni Giovanna 2002 The LHC, the new superconducting particle accelerator presently under construction at CERN, makes use of some 1200 dipole magnets for orbit bending and 500 quadrupole magnets for focusing/defocusing of the circulating high-energy proton beams. Two or three column-type support posts sustain each cryomagnet. The choice of a convenient material for these supports is critical, because of the required high positioning accuracy of the magnets in their cryostats and stringent thermal budget requirements imposed by the LHC cryogenic system. A glass-fibre/epoxy resin composite has been chosen for its good combination of high stiffness and low thermal conductivity over the 2-293 K temperature range. Plies of long glass-fibres are stacked optimally yielding the best mechanical behaviour. However, heat leaks from the supports are influenced by the thermal characteristics of the composite, which in turn depend on the orientation of the fibres. To study the dependence of the thermal conductivity on fibre's orientation, we performed high precision thermal conductivity measurements of various samples of glass-fibre/epoxy resin composite. The results of the thermal conductivity measurements are compared with integral measurements on support posts for LHC cryomagnets and with mixing models. research-article

The liquid krypton calorimeter cryogenics for the NA48 experiment Bremer J Cundy Donald C Dauvergne J P Gonidec A Kesseler G Kubischta Werner Linser G Schinzel D Taureg Hans Wertelaers Piet 1998 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. research-article

Technical Analysis and Statistics from Long Term Helium Cryoplant Operation with Experimental Superconducting Magnets at CERN Dauvergne J P Delikaris D Haug F 1997 CERN regularly uses a large number of liquid helium cryoplants for cooling the superconducting magnets of large particle detectors. They are installed in the experimental areas of the electron-positron collider LEP and the proton (and heavy ion) accelerator SPS for the observation of high-energy interactions of elementary particles. The typical cold mass of a detector magnet ranges from 1 to 40 tons, and typical cryoplant cooling capacities are between 400 and 800 W/4.5 K entropy equivalent. Operation must be very flexible to meet the varying experimental requirements. We intend to present technical data of the system and statistics from over 180'000 running hours during the four years from 1992 to 1995. Operation includes phases of cool-down, steady-state cooling, recovery after magnet quench or other incidents and warm-up of the superconducting magnets. Emphasis will be laid on the analysis of fault conditions, multiple interaction between perturbations and consequences for the users of liquid helium supply interruption. research-article

Thermal Characterization of the HeII LHC Heat Exchanger Tube Camacho D Chevassus S Policella C Rieubland Jean Michel Vandoni Giovanna Van Weelderen R 1998 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. research-article

Phys. Lett. B Phys. Lett. B Three pion correlations in sulphur-lead collisions at the CERN SPS Bøggild H Boissevain J G Dodd J Esumi S C Fabjan Christian Wolfgang Ferenc D Franz A Hardtke D van Hecke H Humanic T J Ikemoto T Jacak B V Kalechofsky H Kobayashi T Kvatadze R A Lee Y Y Leltchouk M Lörstad B Maeda N Miake Y Miyabayashi A Murray M Nagamiya S Nishimura S Paic G Pandey S U Piuz François Polychronakos V Potekhin M V Poulard G Rahm David Charles Rieubland Jean Michel Sakaguchi A Sarabura M Shigaki K Simon-Gillo J Schmidt-Sørensen J Sondheim W E Sugitate T Sullivan J P Sumi Y Willis W J 1999 455 77 83 $\pi^+\pi^+\pi^+$ correlations from Sulphur-Lead collisions at 200 GeV/c per nucleon are presented as measured by the focusing spectrometer of experiment NA44 at CERN. We have investigated the three-pion correlation function at mid-rapidity and found that a genuine three-body correlation is suppressed. A possible interpretation of this result is that the emission of particles is partially coherent. research-article

The $\mu$ polarimeter for experiment SMC at CERN SPS Baum G Bültmann S Thiel W Dulya C M Grosse-Perdekamp M Igo G Trentalange S Whitten C Hautle P Niinikoski T O Rieubland Jean Michel Voss Rüdiger CERN Postma H Brüll A Engelien H Kaiser R Kessler H J Landgraf U Witzmann A Knop W Stuhrmann H B Wagner R Berglund P Kyynäräinen J Lau K Mayes B W Pinsky L Pyrlik J Sanders D Tzamouranis Yu Weinstein R Golutvin I A Kadykov M G Karev A G Kiryushin Yu T Kiselev Yu F Krivokhizhin V G Kukhtin V V Neganov B S Peshekhonov V D Pose D Savin I A Sergeev S Smirnov G Yatsunenko Yu A Von Harrach D Kabuss E M Mallot G K Seitz R Windmolders R Betev L Heusch C A Meyer-Berkhout U Staude A Hasegawa T Hayashi N Horikawa N Ishimoto S Iwata T Kishi A Okumi S Ballintijn M K Van Dantzig R De Jong M Ketel T Klostermann L Van Middelkoop G Oberski J Sever F von Goeler E Moromisato J H Fasching D Miller D Segel R E Shanahan P Velasco M Adams D L Ahmad S Bonner B E Buchanan J Clement J Corcoran M D Cranshaw J Eichblatt S Gaussiran T Loewe M Miettinen H Mutchler G S Roberts J B Bardin G Bird I G De Botton N R Bystrický J Cavata C Faivre Jean-Claude Feinstein F Frois Bernard Lehár F de Lesquen A Magnon A Marie F Martino J Perrot-Kunne F Platchkov S K Pussieux T Adeva B Fernández C Gómez A Garabatos C Garzón J A López-Ponte S Pló M Rodríguez M Saborido J Yañez A Lichtenstadt J Sabo I Birsa R Bradamante Franco Dalla Torre S Giorgi M A Lamanna M Martin A Penzo Aldo L Salvato G Schiavon R P Tessarotto F Villari A C C GANIL, Caen Zanetti A M Arvidson A Björkholm P Dyring A Kullander Sven Lindqvist T Day D Chen J P Crabb D McCarthy J Mitchell J Rondon-Aramayo O A Badelek B Nassalski J P Rondio Ewa Ropelewski Leszek Sandacz A Wislicki W Boutemeur M Butt Y M Dhawan S K Hughes V W Piegaia R Schüler P 1992 research-article

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Tests of industrial ethylene-propylene rubber high voltage cable for cryogenic use Balhan B CERN Blin M CERN Goddard B CERN Muratori G Univ. of California at Los Angeles, USA Otwinowski S Univ. of California at Los Angeles, USA Rieubland Jean Michel CERN Wang H Univ. of California at Los Angeles, USA 1999 At the beginning of 1999 UCLA has received a prototype High Voltage Cryogenic Cable supplied fee of charge by Pirelli. The cable is intended for more than ten years of service at 100 kV D.C. and liquid argon temperature. Thecable uses an all welded construction, whichi is axially tight and free of ionizable voids. The cable was submitted to a number of mechanical and electrical tests as described below. SLINTNOTE

Thermal performance measurements on ATLAS-SCT KB forward modules Donegà M Clark A D'Onofrio M Ferrère D Hirt C Ikegami Y Kohriki T Kondo T Lindsay S Mangin-Brinet M Niinikoski T O Pernegger H Perrin E Taylor G Terada S Unno Y Wallny R Weber M 2003 The thermal design of the KB module is presented. A Finite Elements Analysis (FEA) has been used to finalize the module design. The thermal performance of an outer irradiated KB module has been measured at different cooling conditions. The thermal runaway of the module has been measured. The FEA model has been compared with the measurements and has been used to predict the thermal performance in a realistic SCT scenario. INTNOTEATLASPUBL

AIP Conf. Proc. AIP Conf. Proc. The helium cryogenic plant for the CMS superconducting magnet Perinic G Caillaud A Dagut F Dauguet P Hirel P 2002 613 232 238 A new helium refrigeration plant with a cooling capacity of 800 W at 4.45 K, 4500 W between 60 K and 80 K, and 4 g/s liquefaction simultaneously has been designed and is presently being constructed by Air Liquide for CERN. The refrigeration plant will provide the cooling power for the cool down and the operation of the CMS (Compact Muon Solenoid) superconducting coil whose cold mass weighs 225 t. The refrigeration plant will at first be installed in a surface building for the tests of the superconducting magnet. On completion of the tests the cold box will be moved to its final underground position next to the CMS experimental cavern. This paper presents the process design, describes the main components and explains their selection. (4 refs). research-article

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 The Helium Cryogenic System for the ATLAS Experiment Delruelle N Haug F Passardi Giorgio ten Kate H H J 2000 10 1511 13 The magnetic configuration of the ATLAS detector is generated by an inner superconducting solenoid and three air-core toroids (the barrel and two end-caps), each of them made of eight superconducting coils. Two separated helium refrigerators will be used to allow cool-down from ambient temperature and steady-state operation at 4.5 K of all the magnets having a total cold mass of about 600 tons. In comparison with the preliminary design, the helium distribution scheme and interface with the magnet sub-systems are simplified, resulting in a considerable improvement of the operational easiness and the overall reliability of the system at some expense of the operational flexibility. The paper presents the cryogenic layout and the basic principles for magnets cool-down, steady state operation and thermal recovery after a fast energy dump. research-article

Upgrade of the CERN Cryogenic Station for Superfluid Helium Testing of Prototype LHC Superconducting Magnets Benda V Dauvergne J P Haug F Knoops S Lebrun P Momal F Sergo S Tavian L Vullierme B 1997 research-article

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 The Chimney And Superconducting Bus Lines For The ATLAS Central Solenoid Makida Y KEK, Tanashi Doi Y KEK, Tanashi Yamamoto A KEK, Tanashi Kondo Y KEK, Tanashi Haruyama T KEK, Tanashi Kondo T KEK, Tanashi Wachi Y KEK, Tanashi Mine S KEK, Tanashi Mizumaki S KEK, Tanashi Kobayashi T KEK, Tanashi Hang F KEK, Tanashi Delruelle N KEK, Tanashi Tischhauser Johann KEK, Tanashi Passardi Giorgio KEK, Tanashi ten Kate H H J KEK, Tanashi 2001 11 1590 3 research-article

Test Results of a 1.2 kg/s Centrifugal Liquid Helium Pump for the ATLAS Superconducting Toroid Magnet System Pengo R Junker S Passardi Giorgio Pirotte O ten Kate H H J 2002 The toroid superconducting magnet of ATLAS-LHC experiment at CERN will be indirectly cooled by means of forced flow of liquid helium at about 4.5 K. A centrifugal pump will be used, providing a mass flow of 1.2 kg/s and a differential pressure of 40 kPa (ca. 400 mbar) at about 4300 rpm. Two pumps are foreseen, one for redundancy, in order to feed in parallel the cooling circuits of the Barrel and the two End-Caps toroid magnets. The paper describes the tests carried out at CERN to measure the characteristic curves, i.e. the head versus the mass flow at different rotational speeds, as well as the pump total efficiency. The pump is of the "fullemission" type, i.e. with curved blades and it is equipped with an exchangeable inducer. A dedicated pump test facility has been constructed at CERN, which includes a Coriolis-type liquid helium mass flow meter. This facility is connected to the helium refrigerator used for the tests at CERN of the racetrack magnets of the Barrel and of the End-Cap toroids. research-article

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 The ATLAS magnet test facility at CERN Miele P Acerbi E Baynham D Elwyn Cataneo F Daël A Dudarev A Haug F ten Kate H H J Passardi Giorgio Sbrissa E Schilly P Yamamoto A 2000 10 377 80 The magnet system for the ATLAS detector at CERN consists of a Barrel Toroid (BT), two End-Cap Toroids (ECT) and a Central Solenoid (CS). The overall dimensions of the system are 20 m in diameter by 26 m in length. Before underground installation all coils will be tested on surface in a magnet test facility which is under construction. Moreover two model coils are tested as well as subsystems. In this paper the design and construction of the test facility is presented. (3 refs). research-article

AIP Conf. Proc. AIP Conf. Proc. The Proximity Cryogenic System for the ATLAS Toroidal Magnets Baynham D Elwyn Bradshaw T Brown G Cragg D Crook M Haug F Mayri C Orlowska A H Passardi Giorgio Pengo R ten Kate H H J Rochford J Sole D 2002 613 155 160 ATLAS is a very high-energy detector for the Large Hadron Collider (LHC) at CERN. The superconducting magnet used to provide the required magnetic field consists of four sub-systems: a central solenoid and a very large toroidal magnet comprising two end-cap magnets and the barrel toroid magnet. The associated cryogenic system, currently in the final specification and procurement phase has been sub-divided into three parts: internal, proximity and external. The internal cryogenics minimizes and extracts the heat loads to/from the 4.5 K cold mass and its thermal shields, while the proximity cryogenics takes the cooling capacity generated by the external common system and distributes it to the four magnets according to the various operating scenarios. Two independent proximity cryogenic systems have been designed taking into account the difference in cooling principle of the solenoid and the three toroids, respectively. research-article

The cryogenic system for the superconducting solenoid magnet of the CMS experiment Delikaris D Dauvergne J P Passardi Giorgio Lottin J C Lottin J P Lyraud C 1998 The design concept of the CMS experiment, foreseen for the Large Hadron Collider (LHC) project at CERN, is based on a superconducting solenoid magnet. The large coil will be made of a four layers winding generating the 4 T uniform magnetic induction required by the detector. The length of the solenoid is 13 m with an inner diameter of 5.9 m. The mass kept at liquid helium temperature totals 220 t and the electromagnetic stored energy is 2.7 GJ. The windings are indirectly cooled with a liquid helium flow driven by a thermosyphon effect. The external cryogenic system consists of a 1.5 kW at 4.5 K (entropy equivalent) cryoplant including an additional liquid nitrogen precooling unit and a 5000 litre liquid helium buffer. The whole magnet and cryogenic system will be tested at the surface by 2003 before final installation in the underground area of LHC. PREPRINT

The CERN Cryogenic Test Facility for the Atlas Barrel Toroid Magnets Haug F Cambon A Delruelle N Orlic J P Passardi Giorgio Tischhauser Johann 1999 The superconducting magnet system of the ATLAS detector will consist of a central solenoid, two end-cap toroidal magnets (ECT) and the barrel toroid magnet (BT) made of eight coils symmetrically placed around the central axis of the detector. The magnets will be tested individually in a 5000 m2 experimental area prior to their final installation at an underground cavern of the LHC Collider. For the BT magnets, a dedicated cryogenic test facility has been designed which is currently under the construction and commissioning phase. A liquid nitrogen pre-cooling unit and a 1200 W@4.5K refrigerator will allow flexible operating conditions via a rather complex distribution and transfer line system. Flow of two-phase helium for cooling the coils is provided by centrifugal pumps immersed in a saturated liquid helium bath. The integration of the pumps in an existing cryostat required the adoption of novel mechanical solutions. Tests conducted permitted the validation of the technical design of the cryostat and its instrumentation. The characteristics of one pump were measured and pressure rise of 300 mbar at nominal flow of 80 g/s confirmed the specifications. research-article

The Cryogenic System for the ATLAS Liquid Argon Detector Bremer J 2000 The ATLAS experiment will include three argon detectors of unprecedented size. The total liquid argon fill of the three cryostats is 83 m3. Gas bubble formation which is detrimental for the functioning of the detector is avoided by sub-cooling of the liquid argon volume with saturated liquid nitrogen heat exchangers placed in the cryostats. Furthermore, to prevent degradation of the detector performance, the maximum temperature gradient across the total liquid volume must be kept within 0.6 K. Additional severe constraints are imposed by the request of uninterrupted cryogenic operation during several years and by the safe handling of a large amount of argon in a 100 m deep underground area. research-article

Studies on Cooling of the TOTEM Particle Detector at the LHC Haug F 2005 TOTEM is an experiment at the CERN LHC collider to measure the total pp cross section and elastic scattering of protons. For the detection of the elastically scattered particles at very small angles with respect to the beams edgeless silicon detectors will be contained in 36 small vacuum vessels called “roman pots” to be installed inside the LHC beam vacuum pipe. The final -not yet fixed-operating temperature is expected to be between 130 K and 220 K. The preferred cooling method applies a combination of cryogenic heat pipes and pulse tube refrigerators. research-article

Status of RF superconductivity work at CERN Weingarten Wolfgang Barranco-Luque M Benvenuti Cristoforo Bloess D Boussard Daniel Bressani G Brown P Brunner O C Calatroni Sergio Cavallari Giorgio Chiaveri Enrico Ciapala Edmond Cosso R Darriulat Pierre Durand C Erdt W K Geissler Kryno K Geschonke Günther Güsewell D Häbel E Hauviller Claude Hilleret Noël CERN Kindermann H P Lacarrère D Marino M Nakai H Passardi Giorgio Peschardt E Rieubland Jean Michel Rödel V Russo R Schirm K M Stirbet M Taufer M Tischhauser Johann Tückmantel Joachim Uythoven J Veshcherevich V G Wahl H Wyss C 1996 research-article

Status Report on the Construction of the Mechanical Outer Forward Module Prototypes for the SCT. Fortin R Niinikoski T O Roe S Weilhammer Peter Clark A G Ferrère D Macina Daniela CERN Morone C Perrin E Weber M Zsenei A 2000 It is foreseen to assemble and test ~600 silicon detector modules of the Forward Silicon Tracker (SCT), using facilities at CERN and the University of Geneva. The mechanical tolerances of the modules being constructed are stringent, making the large scale fabrication of detector modules a challenge. An assembly procedure has been developed with the aim of meeting the required mechanical tolerances. The production of four prototype mechanical modules using this procedure is described. Improvements of the assembly technique planned for the production of future forward modules are outlined. INTNOTEATLASPUBL

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 Status of the CMS magnet (MT17) Hervé A Acquistapace G Campi D Cannarsa P Fabbricatore P Feyzi F Gerwig H Grillet J P Horváth I L Kaftanov V S Kircher F Loveless R Maugain J M Perinic G Rykaczewski H Sbrissa E Smith R P Veillet L 2002 12 385 90 The CMS experiment (Compact Muon Solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with a free bore of 6 m diameter and 12.5-m length, enclosed inside a 10 000-ton return yoke. The magnet will be assembled and tested in a surface hall at Point 5 of the LHC at the beginning of 2004 before being transferred by heavy lifting means to an experimental hall 90 m below ground level. The design and construction of the magnet is a common project of the CMS Collaboration. The task is organized by a CERN based group with strong technical and contractual participation from CEA Saclay, ETH Zurich, Fermilab, INFN Genova, ITEP Moscow, University of Wisconsin and CERN. The magnet project will be described, with emphasis on the present status of the fabrication. (15 refs). research-article

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 Status of the construction of the CMS magnet Hervé A Blau Bertrand Brédy P Campi D Cannarsa P Curé B Dupont T F Fabbricatore P Farinon S Feyzi F Fazilleau P Gaddi A Gerwig H Greco Michela Grillet J P Kaftanov V Kircher F Klyukhin V Levesy B Loveless R Maire G Musenich R Pabot Y Payn A Perinic G Petiot P Rondeaux F Rykaczewski H Sbrissa E Sequeira-Lopes-Tavares S Sgobba Stefano Smith R P Veillet L Waurick G 2004 14 542 547 research-article

Refrigeration system for the ATLAS Experiment. LHC Project Report Cragg D Cure C Dauvergne J P Haug F Mayri C Pailler P Passardi Giorgio 1996 INTNOTEATLASPUBL

Refrigeration System for the ATLAS Experiment Cragg D Cure C Dauvergne J P Haug F Mayri C Pailler P Passardi Giorgio Yamamoto A 1997 INTNOTEATLASPUBL

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 Review of the ATLAS B0 model coil test program Dolgetta N Miele P Acerbi E Berriaud C Boxman H Broggi F Cataneo F Daël A Delruelle N Dudarev A Foussat A Haug F ten Kate H H J Mayri C Paccalini A Pengo R Rivoltella G Sbrissa E 2004 14 495 499 The ATLAS B0 model coil has been extensively tested, reproducing the operational conditions of the final ATLAS Barrel Toroid coils. Two test campaigns have taken place on B0, at the CERN facility where the individual BT coils are about to be tested. The first campaign aimed to test the cool-down, warm-up phases and to commission the coil up to its nominal current of 20.5 kA, reproducing Lorentz forces similar to the ones on the BT coil. The second campaign aimed to evaluate the margins above the nominal conditions. The B0 was tested up to 24 kA and specific tests were performed to assess: the coil temperature margin with respect to the design value, the performance of the double pancake internal joints, static and dynamic heat loads, behavior of the coil under quench conditions. The paper reviews the overall test program with emphasis on second campaign results not covered before. 10 Refs. research-article

Refrigeration System for the ATLAS Experiment Haug F Dauvergne J P Passardi Giorgio Cragg D Curé C Pailler P Mayri C Yamamoto A 1997 The proposed ATLAS detector for the 27 km circumference LHC collider is of unprecedented size and complexity. The magnet configuration is based on an inner superconducting solenoid and large superconducting air-core toroids (barrel and two end-caps) each made of eight coils symmetrically arranged outside the calorimetry. The total cold mass approaches 600 tons and the stored energy is 1.7 GJ. The cryogenic infrastructure will include a 6 kW @ 4.5 K refrigerator, a precooling unit and distribution systems and permits flexible operation during cool-down, normal running and quench recovery. A dedicated LN2 refrigeration system is proposed for the three liquid argon calorimeters (84 m3 of LAr). Magnets and calorimeters will be individually tested prior to their definitive installation in a large scale cryogenic test area on the surface. The experiment is scheduled to be operational in 2005. research-article

AIP Conf. Proc. AIP Conf. Proc. Quench Induced Pressure Rise in the Cooling Pipes of the Atlas Barrel Toroid Model Haug F CERN Bottura L CERN Broggi F INFN/LASA, Segrate, Milano, Italy Junker S CERN 2004 710 711 718 The ATLAS superconducting magnet system consists of a Barrel Toroid, two End-Cap Toroids and a Solenoid. Eight individual racetrack coils will be assembled to form the Barrel Toroid with overall dimensions of 26 m length and 20 m diameter. In order to verify the design concept a 9 m long short version of a single Barrel Toroid coil was built. A test program was conducted at the CERN cryogenic test facility which included the evaluation of the pressure rise in the helium cooling channels during quenches of the coil. A specific experimental set-up with cold pressure transducers and capillaries was installed for online measurement of the pressure signals. In addition a computer model was used to simulate these events. The data obtained are presented. research-article

Adv. Cryog. Eng., A Adv. Cryog. Eng., A Precise wide range heatmeters for 1.5 K up to 80 K Ferlin G Jenninger B Rieubland Jean Michel 1998 43 811 818 Two heatmeters were designed at CERN for applications below 20 K with the option to work also at temperatures up to 80 K. The new calibration principle and design permits the construction of wide rang e heatmeters with precision in the range of milliwatts. The calibration function takes into account the temperature dependence of the thermal conductivity of the heatmeter material. The heat flow meas urement is, therefore, independent of the base temperature, i.e. it is also independent on the temperature drop across thermal contact between heatmeter and the cold source. The simple calibration fun ction makes the heatmeter a user-friendly portable diagnostic device. It is possible to quantify parasitic heat flow without a previous calibration, or to calibrate the heatmeter during a measurement with a specimen. research-article

Preliminary Measurements on Micro-Calorimeters Foreseen to Be Used As Beam-Loss Monitors Bosser Jacques CERN Bouyaya H CERN Ferioli G CERN Jenninger B CERN Policella C CERN Rieubland Jean Michel CERN Rijllart A CERN 1996 LHCPROJNOTE

AIP Conf. Proc. AIP Conf. Proc. Performance of a proximity cryogenic system for the ATLAS central solenoid magnet Doi Y Yamamoto A Makida Y Kondo Y Kawai M Aoki K Haruyama T Kondo T Mizumaki S Wachi Y Mine S Haug F Delruelle N Passardi Giorgio ten Kate H H J 2002 613 47 54 The ATLAS central solenoid magnet has been designed and constructed as a collaborative work between KEK and CERN for the ATLAS experiment in the LHC project The solenoid provides an axial magnetic field of 2 Tesla at the center of the tracking volume of the ATLAS detector. The solenoid is installed in a common cryostat of a liquid-argon calorimeter in order to minimize the mass of the cryostat wall. The coil is cooled indirectly by using two-phase helium flow in a pair of serpentine cooling line. The cryogen is supplied by the ATLAS cryogenic plant, which also supplies helium to the Toroid magnet systems. The proximity cryogenic system for the solenoid has two major components: a control dewar and a valve unit In addition, a programmable logic controller, PLC, was prepared for the automatic operation and solenoid test in Japan. This paper describes the design of the proximity cryogenic system and results of the performance test. (7 refs). research-article

Nucl. Instrum. Methods Phys. Res., A Nucl. Instrum. Methods Phys. Res., A 0167-5087 Performance of the ATLAS Electromagnetic Calorimeter End-cap Module 0 Aubert Bernard Abouelouafa M Alexa C Astesan F Augé E Aulchenko V M Ballansat J Barreiro F Barrillon P Battistoni G Bazan A Beaugiraud B Beck-Hansen J Belhorma B Belorgey J Belymam A Ben-Mansour A Benchekroun D Benchouk C Bernard R Bertoli W Boniface J Bonivento W Bourdarios C Bremer J Breton D Bán J Camard A Canton B Carminati L Cartiglia N Chalifour M Chekhtman A Chen H Cherkaoui R Chevalley J L Chollet F Citterio M Clark A Cleland W Clément C Colas Jacques Collot J Costa G Cros P Cunitz H Del Peso J Delebecque P Delmastro M Di Ciaccio Lucia Dinkespiler B Djama F Dodd J Driouichi C Dumont-Dayot N Duval P Y Efthymiopoulos I Egdemir J El-Kacimi M El-Mouahhidi Y Engelmann R Ernwein J Falleau I Fanti M Farrell J Fassnacht P Ferrari A Fichet S Fournier D Gallin-Martel M L Gara A García G Gaumer O Ghazlane H Ghez P Gianotti F Girard C Gordon H Gouanère M Guilhem G Hackenburg B Hakimi M Hassani S Henry-Coüannier F Hervás L Hinz L Hoffman A Hoffman J Hostachy J Y Hoummada A Hubaut F Idrissi A Imbault D Jacquier Y Jevaud M Jérémie A Jézéquel S Kambara H Karst P Kazanin V Kierstead J A Kolachev G M Kordas K de La Taille C Labarga L Lacour D Lafaye R Laforge B Lanni F Le Coroller A Le Dortz O Le Maner C Le Van-Suu A Le Flour T Leite M Leltchouk M Lesueur J Lissauer D Lund-Jensen B Lundqvist J M Ma H Macé G Makowiecki D S Malsyshev V Mandelli L Mansoulié B Marin C P Martin D Martin L Martin O Martin P Maslennikov A L Massol N Mazzanti M McCarthy R McDonald J Megner L Merkel B Mirea A Moneta L Monnier E Moynot M Nagy E Negroni S Neukermans L Nicod D Nikolic-Audit I Noppe J M Ohlsson-Malek F Olivier C Orsini F Pailler P Parrour G Parsons J A Pearce M Perrodo P Perrot G Poggioli Luc Pospelov G E Pralavorio Pascal CRN, IN2P3-CNRS/ULP, Strasbourg, France Prast J Przysiezniak H Puzo P Pétroff P Radeka V Rahm David Charles Rajagopalan S Raymond M Renardy J F Repetti B Rescia S Riccadona X Richer J P Rijssenbeek M Rodier S Rossel F Rousseau D Rydström S Saboumazrag S Sauvage D Sauvage G Schilly P Schwemling P Schwindling J Seguin-Moreau N Seidl W Seman M Serin L Shousharo A Simion S Sippach W Snopkov R Steffens J Stroynowski R Stumer I Taguet J P Takai H Talyshev A A Tartarelli F Teiger J Thion J Tikhonov Yu A Tisserant S Tocut V Tóth J Veillet J J Vossebeld Joost Herman Vuillemin V Wielers M Willis W J Wingerter-Seez I Ye J Yip K Zerwas D Zitoun R Zolnierowski Y 2003 500 178 201r The construction and beam test results of the ATLAS electromagnetic end-cap calorimeter pre-production module 0 are presented. The stochastic term of the energy resolution is between 10% GeV^1/2 and 12.5% GeV^1/2 over the full pseudorapidity range. Position and angular resolutions are found to be in agreement with simulation. A global constant term of 0.6% is obtained in the pseudorapidity range 2.5 < eta < 3.2 (inner wheel). research-article

New Long-term Historical Data Recording and Failure Analysis System for the CERN Cryoplants Barbeau H Barth K Baud R Dauvergne J P Delikaris D 1999 CERN uses several liquid helium cryoplants (total of 21) for cooling large variety of superconducting devices namely: accelerating cavities, magnets for accelerators and particle detectors. The cryoplants are remotely operated from several control rooms using industrial standard supervision systems, which allows the instant display of all plant data and the trends, over several days, for the most important signals. The monitoring of the cryoplant performance during transient conditions and normal operation over several months asks for a long-term recording of all plant parameters. An historical data recording system has been developed, which collects data from all cryoplants, stores them in a centralized database over a period of one year and allows an user-friendly graphical visualization. In particular, a novel tool was developed for debugging causes of plant failures by comparing selected reference data with the simultaneous evolution of all plant data. The paper describes the new system, already in operation with 11 cryoplants. PREPRINT

Measurements of Multi-Layer Insulation at High Boundary Temperature, using a Simple Non-Calorimetric Method Mazzone L Ratcliffe G Rieubland Jean Michel Vandoni Giovanna 2002 In spite of abundant literature, the thermal performance of Multi-Layer Insulation (MLI) still deserves dedicated investigation for specific applications, as the achievable insulation strongly depends on installation details. Furthermore, less accurate information is available for warm than for cold boundaries, since errors due to edge effects in small test benches increase strongly with warm boundary temperature. We establish here the thermal performance of MLI between 300 K and 77 K or 4 K, without bringing calorimetric methods into play, through the accurate measurement of a temperature profile. A cylinder in thin copper, wrapped with MLI, is cooled at one extremity while suspended under vacuum inside a sheath at room temperature. For known thermal conductivity and thickness of the tube, the heat flux can be inferred from the temperature profile. In-situ measurement of the thermal conductivity is obtained by applying a know heat flow at the warm extremity of the cylinder. Results, cross-checked with a calibrated heatmeter, compare well with what previously obtained on a large-scale measuring facility. research-article

Measurement of the Thermal Properties of Prototype Lambda Plates for the LHC Marie R Métral L Perin A Rieubland Jean Michel 2005 In order to power the LHC superconducting magnets, thousands of busbars will be routed from electrical feedboxes containing saturated helium at 4.5 K to magnets operating in pressurized superfluid helium at 1.9 K. Between those two volumes, the busbars will pass through special feedthroughs also called lambdaplates. This article presents heat flow measurements performed on several configurations of vertical prototype lambda-plates feedthroughs. The results show that the heat flow is strongly influenced by the configuration of the busbar insulation in the saturated helium. research-article

Memorandum Amblard B Autones P Cozzika G Derégel J Ducros Y Fontaine G Hansroul M Lehár F de Lesquen A Merlo J P Movchet J Raoul J C Rieubland Jean Michel Van Rossum L 1969 SCICOMMPUBLPHI

Memorandum Amblard B Autones P Cozzika G Derégel J Ducros Y Hansroul M Lehár F de Lesquen A Merlo J P Movchet J Raoul J C Rieubland Jean Michel Van Rossum L 1969 SCICOMMPUBLPHI

Manufacturing of the test cryostat. The test cryostat is used to simulate heat loads of the CMS magnet for the acceptance tests of the refrigeration system. 2002 The picture shows the testing configuration of the helium refrigeration system with the intermediate cryostat (6000l) and the temporary test cryostat. PHOTOCMS

Montage photograph: Cryogenic components mounted on top of the central yoke barrel in the configuration for the acceptance tests of the helium refrigeration system comprising the intermediate cryostat (right), the test cryostat (left) and the cryogenic transfer lines. 2003 The picture shows the cryogenic components mounted on top of the central yoke barrel in the configuration for the acceptance tests of the helium refrigeration system. PHOTOCMS

Measurement and analysis of thermal performance of LHC prototype cryostats Benda V Dufay L Ferlin G Lebrun P Rieubland Jean Michel Riddone G Szeless Balázs Tavian L Williams L 1995 research-article

Lowering of the cryogenic transfer line segments to USC55. 2004 The pictures show the transfer of the helium transfer line segments to the USC55 cavern. The transport of the just under 12m long segments has been achieved by the means of a tilting table. PHOTOCMS

Latest news from the Magnet System Delruelle N CERN Rabbers J J CERN Ruber R University of Uppsala Zaitsev I Russian Institute for High Energy Physics ENEWSPUBLATLAS

Influence of Thermal Cycling on Cryogenic Thermometers Balle C Casas-Cubillos J Rieubland Jean Michel Suraci A Togny F Vauthier N 1999 The stringent requirements on temperature control of the superconducting magnets for the Large Hadron Collider (LHC), impose that the cryogenic temperature sensors meet compelling demands such as long-term stability, radiation hardness, readout accuracy better than 5 mK at 1.8 K and compatibility with industrial control equipment. This paper presents the results concerning long-term stability of resistance temperature sensors submitted to cryogenic thermal cycles. For this task a simple test facility has been designed, constructed and put into operation for cycling simultaneously 115 cryogenic thermometers between 300 K and 4.2 K. A thermal cycle is set to last 71/4 hours: 3 hours for either cooling down or warming up the sensors and 1 respectively 1/4 hour at steady temperature conditions at each end of the temperature cycle. A Programmable Logic Controller (PLC) drives automatically this operation by reading 2 thermometers and actuating on 3 valves and 1 heater. The first thermal cycle was accomplished in a temperature calibration facility and all the thermometers were recalibrated again after 10, 25 and 50 cycles. Care is taken in order not to expose the sensing elements to moisture that can reputedly affect the performance of some of the sensors under investigation. The temperature sensors included Allen-Bradley and TVO carbon resistors, Cernox, thin-film germanium, thin-film and wire-wound Rh-Fe sensors. PREPRINT

Installation of the liquid nitrogen tank for the external cryogenics system 2001 The picture shows the installation of the 50000l liquid nitrogen tank in its first position next to the SHL annex of the SX5 building. The tank will be moved to its final position after the completion of the surface tests. PHOTOCMS

Installation of the intermediate cryostat. 2003 The picture shows the installation of the intermediate cryostat suspended within its support frame. PHOTOCMS

Introduction to cryogenic engineering Perinic Goran CERN Vandoni Giovanna CERN Niinikoski Tapio O CERN 2005 Cryogenic engineering is one of the key technologies at CERN. It is widely used in research and has many applications in industry and last but not least in medicine. In research cryogenic engineering and its applications are omnipresent from the smallest laboratories to fusion reactors, hughe detectors and accelerators. With the termination of the LHC, CERN will in fact become the world's largest cryogenic installation. This series of talks intends to introduce the non-cryogenist to the basic principles and challenges of cryogenic engineering and its applications. The course will also provide a basis for practical application as well as for further learning. VIDEOARC

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 Installation and commissioning of the helium refrigeration system for the CMS Magnet Perinic G Dupont T F Legrand Dominique Pezzetti M 2004 14 1708 1710 A new helium refrigeration plant with a cooling capacity of 800 W at 4.45 K, 4500 W between 60 K and 80 K, and 4 g/s liquefaction simultaneously has been installed in its temporary position inside the Compact Muon Solenoid assembly hall at CERN. The commissioning of the compressor station has been achieved, the commissioning of the cold box and the cryostats is under way. First operation results are presented. research-article

Installation of the Liquid Argon Calorimater Barrel in the ATLAS Experimental Cavern Vandoni G. CERN ENEWSPUBLATLAS

Ann. Phys. Ann. Phys. Is the Lorentz signature of the metric of spacetime electromagnetic in origin? Itin Y Hehl F W 2004 312 60 83 We formulate a premetric version of classical electrodynamics in terms of the excitation H and the field strength F. A local, linear, and symmetric spacetime relation between H and F is assumed. It yields, if electric/magnetic reciprocity is postulated, a Lorentzian metric of spacetime thereby excluding Euclidean signature (which is, nevertheless, discussed in some detail). Moreover, we determine the Dufay law (repulsion of like charges and attraction of opposite ones), the Lenz rule (the relative sign in Faraday's law), and the sign of the electromagnetic energy. In this way, we get a systematic understanding of the sign rules and the sign conventions in electrodynamics. The question in the title of the paper is answered affirmatively. research-article

Heat Flow Measurements on LHC Components Camacho D Chevassus S Ferlin G Pangallo M Policella C Rieubland Jean Michel Simon L Vandoni Giovanna 1999 The refrigeration and liquefaction capacity necessary to operate at 1.9 K the 27 km long string of superconducting magnets of the LHC has been determined on the basis of heat load estimates, including static heat inleaks from ambient temperature, resistive heating and dynamic beam-induced heat loads. At all temperature levels, the static heat inleaks determine at least one third of the total heat loads in nominal operating conditions of the machine. Design validation of individual cryocomponents therefore requires a correct estimate of the heat inleaks they induce at all temperature levels, in order not to exceed the allocated heat budget. This paper illustrates the measurements of heat inleaks for several cold components of the future machine, including insulating supports, radiation shields, multi-layer insulation, instrumentation current leads. Distinct methods to determine the heat flow are chosen, depending on the expected heat loads, the temperature range spanned by the heat intercepts, and the working conditions of the component itself. PREPRINT

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 Heat Load Measurements on a Large Superconducting Magnet Pengo R Dolgetta N Junker S Passardi Giorgio ten Kate H H J 2004 14 1704 1707 ATLAS is one of the two major experiments of the LHC project at CERN using cryogenics. The superconducting magnet system of ATLAS is composed of the Barrel Toroid (BT), two End Caps Toroids and the Central Solenoid. The BT is formed of 8 race-track superconducting dipoles, each one 25 m long and 5 m wide. A reduced scale prototype (named B0) of one of the 8 dipoles, about one third of the length, has been constructed and tested in a dedicated cryogenic facility at CERN. To simulate the final thermal and hydraulic operating conditions, the B0 was cooled by a forced flow of 4.5 K saturated liquid helium provided by a centrifugal pump of 80 g/s nominal capacity. Both static and dynamic heat loads, generated by the induced currents on the B0 casing during a slow dump or a ramp up, have been measured to verify the expected thermal budget of the entire BT. The instrument used for the heat load measurements was a Void Fraction Meter (VFM) installed on the magnet return line. The instrument constructed at CERN was calibrated in order to provide direct readings of heat loads. An example of application of the VFM measuring method to a largescale apparatus cooled at liquid helium temperature. research-article

High capacity Helium purifier for 14 g/s at 200 bar Neumann H ITP, Forschunszentrum, Karlsruhe Perinic G CERN 2000 research-article

Helium Tank for Cryoplant 2001 Helium Tank point5 PHOTOCMS

Fluorocarbon evaporative cooling developments for the ATLAS pixel and semiconductor tracking detectors Anderssen E Bintinger D L Berry S Bonneau P Bosteels Michel Bouvier P Cragg D English R Godlewski J Górski B Grohmann S Hallewell G D Hayler T Ilie S Jones T Kadlec J Lindsay S Miller W Niinikoski T O Olcese M Olszowska J Payne B Pilling A Perrin E Sandaker H Seytre J F Thadome J Vacek V 1999 Heat transfer coefficients 2-5.103 Wm-2K-1 have been measured in a 3.6 mm I.D. heated tube dissipating 100 Watts - close to the full equivalent power (~110 W) of a barrel SCT detector "stave" - over a range of power dissipations and mass flows in the above fluids. Aspects of full-scale evaporative cooling circulator design for the ATLAS experiment are discussed, together with plans for future development. INTNOTEATLASPUBL

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Factory acceptance of the compressor skids at Samifi-Babcock. All pictures show the second stage compressor skid. 2001 Most recent pictures taken during the factory acceptance of the compressor skids at Samifi-Babcock. All pictures show the second stage compressor skid. Picture two was taken during the leak tests and shows all the pockets around flanges and valves. PHOTOCMS

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 First Cryogenic Testing of the ATLAS Superconducting Prototype Magnets Delruelle N Dudarev A Haug F Mayri C Orlic J P Passardi Giorgio Pirotte O ten Kate H H J 2002 12 1336 1338 The superconducting magnet system of the ATLAS detector will consist of a central solenoid, two end-cap toroids and the barrel toroid made of eight coils (BT) symmetrically placed around the central axis of the detector. All these magnets will be individually tested in an experimental area prior to their final installation in the underground cavern of the LHC collider. A dedicated cryogenic test facility has been designed and built for this purpose. It mainly consists of a 1'200 W at 4.5 K refrigerator, a 10 kW liquid nitrogen pre-cooling unit, a cryostat housing liquid helium centrifugal pumps, a distribution valve box and transfer lines. Prior to the start of the series tests of the BT magnets, two model coils are used at this facility. The first one, the so-called B00 of comparatively small size, contains the three different types of superconductors used for the ATLAS magnets which are wound on a cylindrical mandrel. The second magnet, the B0, is a reduced model of basically identical design concept as the final BT magnets. Full commissioning of all sub-systems including cryogenics, electrical powering, magnet protection and control is done ahead of the arrival of the BT series magnets. This cryogenic test facility reproduces the final thermo-hydraulic conditions in the cooling circuits of the magnets in order to validate the design concept. research-article

Final Testing of the ATLAS Central Solenoid before Installation Haug F Doi Y Haruyama T Kawai M Kondo T Kondo Y Makida Y Metselaar J Passardi Giorgio Pavlov O Pezzetti M Pirotte O Ruber Roger J M Y Sbrissa E ten Kate H H J Tyrvainen H Yamamoto A 2005 The central solenoid is part of the superconducting magnet system of the ATLAS experiment at the CERN LHC collider. It provides a 2 tesla axial magnetic field for the inner 24 m3 volume centre particle tracker. Design and construction was done in Japan by KEK and Toshiba in collaboration with CERN. Factory tests were made in Japan with the proximity cryogenics in a geometrical arrangement corresponding to the final installation and, a full magnet test. After shipment to CERN the proximity cryogenics has been installed at a surface hall and recommissioning with load simulations and the instrumentation adapted for radiation hard requirements at the final underground area. The solenoid has recently been integrated in the common cryostat vessel of the liquid argon barrel. Cool down for final surface testing has started. The final control systems architecture and process logics are applied which is tested. research-article

AIP Conf. Proc. AIP Conf. Proc. Conclusions from 12 Years Operational Experience of the Cryoplants for the Superconducting Magnets of the LEP Experiments Barth K Dauvergne J P Delikaris D Passardi Giorgio 2002 613 247 254 The Large Electron Positron Collider (LEP) has ended its last physics run in November 2000, and it is at present being dismantled to liberate the tunnel for the Large Hadron Collider (LHC) project to be completed by end of 2005. The cryogenic systems for the superconducting solenoid and focusing quadrupoles for the two LEP experiments, ALEPH and DELPHI, each supplying a cooling power of 800 W/4.5 K entropy equivalent, have accumulated more then 100'000 hours of running time. The paper summarises the 12 years cryogenic experience in the various operating modes: cool-down, steady state, recovery after energy fast dump, utilities failures and warm-up of the superconducting magnets. The detailed operation statistics is presented and compared to the other CERN cryogenic systems. Emphasis is given to the technical analysis of the fault conditions and of their consequences on the helium refrigeration production time in view of the future operation of the LHC cryogenics. research-article

Cryogenics for Particle Accelerators and Detectors Lebrun P Tavian L Vandoni Giovanna Wagner U 2002 Cryogenics has become a key ancillary technology of particle accelerators and detectors, contributing to their sustained development over the last fifty years. Conversely, this development has produced new challenges and markets for cryogenics, resulting in a fruitful symbiotic relation which materialized in significant technology transfer and technical progress. This began with the use of liquid hydrogen and deuterium in the targets and bubble chambers of the 1950s, 1960s and 1970s. It developed more recently with increasing amounts of liquefied noble gases - mainly argon, but also krypton and even today xenon - in calorimeters. In parallel with these applications, the availability of practical type II superconductors from the early 1960s triggered the use of superconductivity in large spectrometer magnets - mostly driven by considerations of energy savings - and the corresponding development of helium cryogenics. It is however the generalized application of superconductivity in particle accelerators - RF acceleration cavities and high-field bending and focusing magnets - which has led to the present expansion of cryogenics, with kilometer-long strings of helium-cooled devices, powerful and efficient refrigerators and superfluid helium used in high tonnage as cooling medium. This situation was well reflected over the last decades by the topical courses of the CERN Accelerator School (CAS). In 1988, CAS and DESY jointly organized the first school on Superconductivity in Particle Accelerators, held at Haus Rissen in Hamburg, where I shared the h. and duty of lecturing on cryogenics with Professor J.L. Olsen of ETH Z rich, while P. Seyfert of CEA Grenoble delivered an evening seminar on superfluidity. This successful school was reiterated in 1995, with cryogenics being addressed by Professor W.F. Vinen of University of Birmingham (superfluidity), as well as J. Schmid (thermodynamics and refrigeration) and myself (superfluid helium technology) of CERN. In the CAS School on Superconductivity and Cryogenics for Particle Accelerators and Detectors held in May 2002 in Erice, Sicily, I am particularly pleased to see a more complete syllabus in cryogenics, most of which is covered by CERN colleagues and published in this report. This is in my view, another sign of the development and vitality of this discipline at CERN, primarily in the LHC division which, by virtue of its mandate and competence, is presently building the largest helium cryogenic system in the world for the Large Hadron Collider and its experiments. I hope this report constitutes a useful source of information and updated reference for our staff dedicated to this formidable endeavour. PREPRINT

AIP Conf. Proc. AIP Conf. Proc. Commissioning and First Operation of the Cryogenics for the CERN Axion Solar Telescope (CAST) Barth K Delikaris D Passardi Giorgio Pezzetti M Pirotte O Stewart L Vullierme B Walckiers L Zioutas Konstantin 2004 710 168 175 A new experiment, the CERN Axion Solar Telescope (CAST) was installed and commissioned in 2002. Its aim is to experimentally prove the existence of an as yet hypothetical particle predicted by theory as a solution of the strong CP problem and possible candidate for galactic dark matter. The heart of the detector consists of a decommissioned 10-m long LHC superconducting dipole prototype magnet, providing a magnetic field of up to 9.5 T. The whole telescope assembly is aligned with high precision to the core of the sun. If they exist, axions could be copiously produced in the core of the sun and converted into photons within the transverse magnetic field of the telescope. The converted low-energy solar axion spectrum, peaked around a mean energy of 4.4 keV, can then be focused by a special x-ray mirror system and detected by low-background photon detectors, installed on each end of the telescopes twin beam pipes. This paper describes the external and proximity cryogenic system and magnet commissioning as well as the first operational experience with the overall telescope assembly. research-article

Cryogenics at CERN Passardi Giorgio Tavian L 2002 The use of cryogenics at CERN was originated (in the 1960s) by High Energy Physics detectors requiring low temperature technologies to achieve the desired performance and indicates a sustained trend during the entire evolution of the CERN experimental program. More recently (in the 1980s) the need of cryogenics for CERN accelerators has shown an impressive increase due to the development of superconducting accelerating cavities and high field bending magnets. Today, the two largest detectors (ATLAS and CMS) of the LHC accelerator ask for a considerable variety of cryogenic equipments and the 27 km LHC magnets ring requires the largest 1.8 K helium refrigeration and distribution systems in the world. The status of CERN cryogenics is briefly reviewed including those systems not related to the LHC complex. research-article

Cryogenics for the CERN Solar Axion Telescope (CAST) using a LHC Dipole Prototype Magnet Barth K Passardi Giorgio Pezzetti M Pirotte O Riege H Vullierme B Walckiers L Zioutas Konstantin 2002 The axion, an as yet hypothetical particle predicted from the solution of the strong CP problem, constitutes a prime candidate for the galactic dark matter and also arises in supersymmetry and superstring theories. If existing, axions should be copiously produced in stellar interiors and there are theoretical expectations for a low-energy axion emission spectrum peaked around a mean energy of ~ 4.4 keV. To provide the experimental proof, a solar axion telescope is at present installed at CERN, which is expected to be in total 10-12 times more efficient than the present largest set-up in operation at the University of Tokyo. The telescope will use a decommissioned 10-m long LHC superconducting dipole prototype magnet, providing a magnetic field of 9 T in operation, to catalyse the solar axion to photon conversion, which then can be detected by low-background x-ray detectors. The paper describes the external and proximity cryogenic systems and their integration into the overall telescope assembly. research-article

Cryogenic Facilities at 1.9 K for the Reception of the Superconducting Wires and Cables of the LHC Dipoles Magnets Barth K Dauvergne J P Delruelle N Ferlin G Juillerat A C Pirotte O 2000 CERN's LHC project has moved to an implementation phase. The fabrication of 1600 high-field superconducting magnets operating at 1.9 K will require about 6400 km of Nb-Ti cables. A cryogenic test facility has therefore been set up in order, on the one hand, to verify the quality of individual wires and, on the other hand, to control the critical current of the assembled cables. The facility is composed of a helium liquefier, a transfer line, a dewar and pumps. The paper describes the fully automatic operation of this installation and the different test cycles applied to these wires and cables. research-article

Cryogenics for CERN experiments Bremer J Dauvergne J P Delikaris D Delruelle N Kesseler G Passardi Giorgio Rieubland Jean Michel Tischhauser Johann Haug F 1997 Use of cryogenics at CERN was originated (in the 1960s) by bubble chambers and the associated s.c. solenoids. Complex cryoplants were installed to provide cooling at LH2 and LHe temperatures. Continuity (in the 1970s) in He cryogenics for experiments was provided by spectrometer magnets for fixed target physics of the SPS accelerator. More recently (in the 1980s), large "particle-transparent" s.c. solenoids for collider experiments (LEP) have been built demanding new cryoplants. The LHC experiments (in the 2000s) will continue the tradition with s.c. dipoles (ALICE and LHCb), solenoids (CMS, ATLAS) and toroids (ATLAS) of unusual size. Cryogenics for experiments using noble liquids follows the same trend since the development (in the 1970s) of the first shower LAr detectors. A LKr calorimeter (about 10 m3) will be operated in 1996 and the ATLAS experiment foresees a set of three huge LAr calorimeters (almost 90 m3 total volume of liquid) to be installed underground. research-article

Cryogenic R&D at the CERN Central Cryogenic Laboratory Blin M Ferlin G Gauss P Policella C Rieubland Jean Michel Vandoni Giovanna 1998 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. research-article

Components of the test cryostat. 2001 The pictures show components of the test cryostat which will simulate the cold mass and its shield during the comissioning of the external cryogenics plant. The test cryostat shall allow to test all possible operation modes of the CMS magnet - cool down and normal operation as well as emergency cooling modes. PHOTOCMS

Compressor station of the external cryogenic system during installation. 2002 The picture shows the compressor station for the external cryogenics system in an advanced stage of installation. PHOTOCMS

Cryogenic cold box during installation. 2003 The picture shows the cold box on the SHL platform during installation work. PHOTOCMS

Cryogenics for the Large Hadron Collider Experiments Bremer J Delikaris D Delruelle N Haug F Passardi Giorgio Perinic G 2000 High Energy Physics experiments have frequently adopted cryogenic versions of their apparatus to achieve the desired performance. Among the four new experiments for the CERN Large Hadron Collider (LHC) the two largest, ATLAS and CMS, include spectrometers using 4.5 K superconducting magnets and detectors filled with liquid argon at 87 K, respectively for particle momentum and energy measurements. These detectors are of unprecedented size and complexity and the definition of the associated cryogenic systems is the result of a collaboration between CERN and several external institutes all around the world. A review of the various systems is presented with particular emphasis to the basic cooling principles, the special cryogenic features and the operation scenarios. PREPRINT

Cryogenics Safety Review of the ATLAS Experiment at CERN Haug F 2005 The ATLAS detector at CERN to be installed at 90 m depth in a 50,000 m3 underground cavern is of unprecedented size and complexity. This is reflected in the helium and nitrogen cryogenic systems required respectively by the magnets (three large superconducting toroids and the central solenoid with 1.6 GJ stored energy) and by the argon calorimeters containing 82 m3 of liquid which can be drained into two 50 m3 dewars in case of emergency. Further coolants of 11 m3 of liquid helium and 15 m3 of liquid nitrogen are stored underground. The potential hazards of the large quantities of cryogens in underground areas require specific attention. Design, construction and quality assurance strictly follow applicable safety rules and the cryogenic process and controls are conceived to actively cope with a number of faults. In severe cases of accidental coolant loss (helium, nitrogen) or argon, detection systems produce alarms which result in the activation of emergency gas extraction. Reviews with international experts confirmed the good safety standard of the systems. research-article

Computer Simulation of the Cool Down of the ATLAS Liquid Argon Barrel Calorimeter Korperud N Bremer J Fabre C Owren G Passardi Giorgio 2002 The ATLAS electromagnetic barrel calorimeter consists of a liquid argon detector with a total mass of 120 tonnes. This highly complicated structure, fabricated from copper, lead, stainless steel and glass-fiber reinforced epoxy will be placed in an aluminum cryostat. The cool down process of the detector will be limited by the maximum temperature differences accepted by the composite structure so as to avoid critical mechanical stresses. A computer program simulating the cool down of the detector by calculating the local heat transfer throughout a simplified model has been developed. The program evaluates the cool down time as a function of different contact gasses filling the spaces within the detector. research-article

Application of Object-Based Industrial Controls for Cryogenics Casas-Cubillos J Gayet P Gomes P Pezzetti M Sicard Claude Henri Varas F J 2002 The first application of the CERN Unified Industrial Control system (UNICOS) has been developed for the 1.8 K refrigerator at point 1.8 in mid-2001. This paper presents the engineering methods used for application development, in order to reach the objectives of maintainability and reusability, in the context of a development done by an external consortium of engineering firms. It will also review the lessons learned during this first development and the improvements planned for the next applications. research-article

A Microcryostat for Refrigeration at 1.8 K Bouyaya A Policella C Rieubland Jean Michel Vandoni Giovanna 1998 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. research-article

Arrival of the cold box for the cryogenic refrigeration plant and installation in building SHL5. 2002 The pictures show the arrival of the cold box and the installation of both the cold box and the valve panel in building SHL5. The installation was achieved by lowering the components through an opening in the roof which had been specially forseen for this operation. PHOTOCMS

IEEE Trans. Appl. Supercond. IEEE Trans. Appl. Supercond. 1051-8223 ATLAS magnet common cryogenic, vacuum, electrical and control systems Miele P Cataneo F Delruelle N Geich-Gimbel C Haug F Olesen G Pengo R Sbrissa E Tyrvainen H ten Kate H H J 2004 14 504 508 The superconducting Magnet System for the ATLAS detector at the LHC at CERN comprises a Barrel Toroid, two End Cap Toroids and a Central Solenoid with overall dimensions of 20 m diameter by 26 m length and a stored energy of 1.6 GJ. Common proximity cryogenic and electrical systems for the toroids are implemented. The Cryogenic System provides the cooling power for the 3 toroid magnets considered as a single cold mass (600 tons) and for the CS. The 21 kA toroid and the 8 kA solenoid electrical circuits comprise both a switch-mode power supply, two circuit breakers, water cooled bus bars, He cooled current leads and the diode resistor ramp-down unit. The Vacuum System consists of a group of primary rotary pumps and sets of high vacuum diffusion pumps connected to each individual cryostat. The Magnet Safety System guarantees the magnet protection and human safety through slow and fast dump treatment. The Magnet Control System ensures control, regulation and monitoring of the operation of the magnets. The updated design, layout, development and construction of the systems, as well as the first results of prototyping and commissioning are presented. 10 Refs. research-article

A full-scale thermal model of a prototype dipole cryomagnet for the CERN LHC project Dufay L Ferlin G Lebrun P Riddone G Rieubland Jean Michel Rijllart A Szeless Balázs Williams L 1994 research-article

A Facility for Accurate Heat Load and Mass Leak Measurements on Superfluid Helium Valves Bézaguet Alain-Arthur Dufay L Ferlin G Losserand-Madoux R Perin A Vandoni Giovanna Van Weelderen R 1999 The superconducting magnets of the Large Hadron Collider (LHC) will be protected by safety relief valves operating at 1.9 K in superfluid helium (HeII). A test facility was developed to precisely determine the heat load and the mass leakage of cryogenic valves with HeII at their inlet. The temperature of the valve inlet can be varied from 1.8 K to 2 K for pressures up to 3.5 bar. The valve outlet pipe temperature can be regulated between 5 K and 20 K. The heat flow is measured with high precision using a Kapitza-resistance heatmeter and is also crosschecked by a vaporization measurement. After calibration, a precision of 10 mW for heat flows up to 1.1 W has been achieved. The helium leak can be measured up to 15 mg/s with an accuracy of 0.2 mg/s. We present a detailed description of the test facility and the measurements showing its performances. PREPRINT

AIP Conf. Proc. AIP Conf. Proc. A Large-scale Test Facility for Heat Load Measurements down to 1.9 K Dufay L Policella C Rieubland Jean Michel Vandoni Giovanna 2002 613 98 105 Laboratory-scale tests aimed at minimizing the thermal loads of the LHC magnet cryostat have gone along with the development of the various mechanical components. For final validation of the industrial design with respect to heat inleaks between large surfaces at different temperatures, a full-scale test cryostat has been constructed. The facility reproduces the same pattern of temperature levels as the LHC dipole cryostat, avoiding the heat inleaks from local components like supports and feedthroughs and carefully minimizing fringe effects due to the truncated geometry of the facility with respect to the LHC cryostats serial layout. Thermal loads to the actively cooled radiation screen, operated between 50 K and 65 K, are measured by enthalpy difference along its length. At 1.9 K, the loads are obtained from the temperature difference across a superfluid helium exchanger. On the beam screen, the electrical power needed to stabilize the temperature at 20 K yields a direct reading of the heat losses. Precise in-situ calibration is achieved by subcooling the thermal screen, thereby zeroing radiative heat loads. Minimizing fringe effects has been rewarded by a high precision measurement, yielding one of the more accurate quantifications to date of an industrial application of MLI. The influence of possible openings in the thermal screen is monitored both at the 1.9 K bath and with a radiation sensitive bolometer. research-article