Slits, Ivo
Bourcey, Nicolas
Canetti, Marco
Colombet, Thierry
Gangini, Fabrizio
Parma, Vittorio
Tock, Jean-Philippe
Design, Manufacturing and Integration of LHC Cryostat Components: an Example of Collaboration between CERN and Industry
The components for the LHC cryostats and interconnections are supplied by European industry. The manufacturing, assembly and testing of these components in accordance with CERN technical specifications require a close collaboration and dedicated approach from the suppliers. This paper presents the different phases of design, manufacturing, testing and integration of four LHC cryostat components supplied by RIAL Vacuum (Parma, Italy), including 112 Insulation Vacuum Barriers (IVB), 482 Cold-mass Extension Tubes (CET), 121 cryostat vacuum vessel Jumper Elbows (JE) and 10800 Interconnection Sleeves (IS). The Quality Assurance Plan, which the four projects have in common, is outlined. The components are all leak-tight thin stainless steel assemblies (<10-8 mbar l/s), most of them operating at cryogenic temperature (2 K), however each having specific requirements. The particularities of each component are presented with respect to manufacturing, assembly and testing. These components are being integrated at CERN into the LHC cryostats and interconnections, thus validating the design and production quality. The major difficulties and improvements are discussed.
eng
CERN;
LHC;
controls;
cryogenics;
vacuum;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-959;
https://accelconf.web.cern.ch/e06/PAPERS/THPCH169.PDF;
http://cds.cern.ch/record/977779/files/lhc-project-report-959.pdf;
Imported from Invenio.
Sammut, N
Bottura, L
Micallef, J
Sanfilippo, S
The Field Description Model for the LHC Quadrupole Superconducting Magnets
The LHC control system requires an accurate forecast of the magnetic field and the multipole field errors to reduce the burden on the beam-based feed-back. The Field Description for the LHC (FIDEL) is the core of this forecast system and is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet apertures. The effects are quantified using the data obtained from series magnetic measurements at CERN and they are consequently modelled empirically or theoretically depending on the complexity of the physical phenomena. This paper presents a description of the methodology used to model the field of the LHC magnets particularly focusing on the results obtained for the LHC main quadrupoles (MQ) and insertion region wide aperture quadrupoles (MQY).
eng
CERN;
LHC;
controls;
insertion;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-958;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS103.PDF;
http://cds.cern.ch/record/977778/files/lhc-project-report-958.pdf;
Imported from Invenio.
Venturini-Delsolaro, W
Bottura, L
Chaudhari, Y
Karppinen, M
Sammut, N
Measurement and Modeling of Magnetic Hysteresis in the LHC Superconducting Correctors
The Large Hadron Collider, now under construction at CERN, relies heavily on superconducting magnets for its optics layout: besides the main magnets, almost all the correcting magnets are superconducting. Along with clear advantages, this brings about complications due to the effects of persistent currents in the superconducting filaments. Corrector magnets that trim key beam parameters or compensate field errors of the main magnets (among others those due to hysteresis), are in their turn hysteretic. In this paper we present the measured magnetic hysteresis and its possible influence on accelerator operation, with particular reference to realtime compensation of dynamic effects in the main magnets, and reproducibility issues between runs. The modeling strategy as a function of the required accuracy is discussed, and two examples are presented.
eng
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-957;
https://accelconf.web.cern.ch/e06/PAPERS/WEPCH048.PDF;
http://cds.cern.ch/record/977777/files/lhc-project-report-957.pdf;
Imported from Invenio.
Sammut, N
Bottura, L
Micallef, J
Sanfilippo, S
The Dependence of the Field Decay on the Powering History of the LHC Superconducting Dipole Magnets
The decay of the allowed multipoles in the Large Hadron Collider (LHC) dipoles is expected to perturb the beam stability during the particle injection. The decay amplitude is largely affected by the powering history of the magnet and is particularly dependent on the pre-cycle flat-top current and duration as well as the pre-injection preparation duration. With possible prospects of having different genres of cycles during the LHC operation, the powering history effect must be taken into account in the Field Description Model for the LHC and must hence be corrected during machine operation. This paper presents the results of the modelling of this phenomenon.
eng
CERN;
LHC;
collider;
dipole;
injection;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-956;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS104.PDF;
http://cds.cern.ch/record/977776/files/lhc-project-report-956.pdf;
Imported from Invenio.
Karppinen, M
Boyer, C
Castro, J-M
Gaggero, G
Giloux, C
Lopes, H
Khare, P
Loche, L
Mazet, J
Mugnai, G
Puntambekar, A
Remondino, Vittorio
Rodrigues, D
Tassisto, M
Venturini-Delsolaro, W
Wolf, R
Design, Performance and Series Production of Superconducting Trim Quadrupoles for the Large Hadron Collider
The Large Hadron Collider (LHC) will be equipped with several thousands of superconducting corrector magnets. Among the largest ones are the superconducting trim quadrupoles (MQTL). These twin-aperture magnets with a total mass of up to 1700 kg have a nominal gradient of 129 T/m at 1.9 K and a magnetic length of 1.3 m. Sixty MQTL are required for the LHC, 36 operating at 1.9 K in and 24 operating at 4.5 K. The paper describes the design features, and reports the measured quench performance and magnetic field quality of the production magnets. The MQTL magnet production is shared between CERN and industry. This sharing is simplified due to the modular construction, common to all twin-aperture correctors.
eng
CERN;
LHC;
insertion;
quadrupole;
target;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-969;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS106.PDF;
http://cds.cern.ch/record/977792/files/lhc-project-report-969.pdf;
Imported from Invenio.
Garion, C
Slits, I
Tock, J P
Installation and Quality Assurance of the Interconnections between Cryo-assemblies of the LHC Long Straight Sections
The interconnections between the cryomagnets and cryogenic utilities in the LHC long Straight Sections constitute the last machine installation activity. They are ensuring continuity of the beam and insulation vacuum systems, cryogenic fluid and electrical circuits and thermal insulation. The assembly is carried out in a constraining tunnel environment with restricted space. Therefore, the assembly sequence has to be well defined and specific tests have to be performed during the interconnection work to secure the reliability of the system and thus to ensure the global accelerator availability. The LHC has 8 long straight insertion zones composed of special cryomagnets involving specific interconnection procedures and QA plans. The aim of this paper is to present the installation and quality assurance procedures implemented for the LHC LSS interconnections. Technologies such as manual and automatic welding and resistive soldering will be described as well as the different quality controls, such as visual and radiographic inspection of welds, electrical checks and leak testing. An evaluation and statistical analysis of the results of the interconnection work will be presented.
eng
CERN;
LHC;
controls;
cryogenics;
vacuum;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-968;
https://accelconf.web.cern.ch/e06/PAPERS/THPCH183.PDF;
http://cds.cern.ch/record/977791/files/lhc-project-report-968.pdf;
Imported from Invenio.
Garion, C
Poncet, A
Seyvet, F
Sitko, M
Skoczen, B
Tock, J P
Copper Heat Exchanger for the External Auxiliary Bus-Bars Routing Line in the LHC Insertion Regions
The corrector magnets and the main quadrupoles of the LHC dispersion suppressors are powered by a special superconducting line (called auxiliary bus-bars line N), external to the cold mass and housed in a 50 mm diameter stainless steel tube fixed to the cold mass. As the line is periodically connected to the cold mass, the same gaseous and liquid helium cools both the magnets and the line. The final sub-cooling process (from around 4.5 K down to 1.9 K) consists in the phase transformation from liquid to superfluid helium. Heat is extracted from the line through the magnets via their point of junction. In dispersion suppressor zones, approximately 40 m long, the sub-cooling of the line is slightly delayed with respect to the magnets. This might have an impact on the readiness of the accelerator for operation. In order to accelerate the process, a special heat exchanger has been designed. It is located in the middle of the dispersion suppressor portion of the line. Its main function consists in providing a local point of heat extraction, creating two additional lambda fronts that propagate in opposite directions towards the extremities of the line. Both the numerical model and the sub-cooling analysis are presented in the paper for different configurations of the line. The design, manufacturing and integration aspects of the heat exchanger are described.
eng
CERN;
LHC;
cryogenics;
insertion;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-967;
https://accelconf.web.cern.ch/e06/PAPERS/MOPCH191.PDF;
http://cds.cern.ch/record/977790/files/lhc-project-report-967.pdf;
Imported from Invenio.
Rossi, Adriana
H2 Equilibrium Pressure with a Neg-Coated Vacuum Chamber as a Function of Temperature and H2 Concentration
Non Evaporable Getter (NEG) coating is used in the Large Hadron Collider (LHC) room-temperature sections to ensure a low residual gas pressure for its properties of distributed pumping, low outgassing and desorption under particle bombardment; and to limit or cure electron cloud build-up due to its low secondary electron emission. In certain regions of the LHC, and in particular close to the beam collimators, the temperature of the vacuum chamber is expected to rise due to energy deposition from particle losses. Hydrogen molecules are pumped by the NEG via dissociation on the surface, sorption at the superficial sites and diffusion into the NEG bulk. In the case of hydrogen, the sorption is thermally reversible, causing the dissociation pressure to increase with NEG temperature and amount of H2 pumped. Measurements were carried out on a stainless steel chamber coated with TiZrV NEG as a function of the H2 concentration and the chamber temperature, to estimate the residual gas pressure in the collimator regions for various LHC operation scenarios, corresponding to different particle loss rates and times between NEG regenerations. The results are presented in this paper and discussed.
eng
LHC;
collider;
injection;
instrumentation;
vacuum;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-966;
https://accelconf.web.cern.ch/e06/PAPERS/TUPCH183.PDF;
http://cds.cern.ch/record/977788/files/lhc-project-report-966.pdf;
Imported from Invenio.
Veness, R
Goddard, B
Massidda, L
Mathot, S J
Presland, A
Design of the LHC Beam Dump Entrance Window
7 TeV proton beams from the LHC are ejected through a 600 m long beam dump transfer line vacuum chamber to a beam dump block. The dump block is contained within an inert gas-filled vessel to prevent a possible fire risk. The dump vessel and transfer line are separated by a 600 mm diameter window, which must withstand both the static pressure load and thermal shock from the passage of the LHC beam. In a previous paper [1] the functional requirements and conceptual design of this window were outlined. This paper describes the analysis leading to the final design of the window. The choice of materials is explained and tests performed on the prototype window are summarized.
eng
CERN;
LHC;
kicker;
proton;
vacuum;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-965;
https://accelconf.web.cern.ch/e06/PAPERS/TUPLS123.PDF;
http://cds.cern.ch/record/977787/files/lhc-project-report-965.pdf;
Imported from Invenio.
Savary, F
Bajko, M
Beauquis, J
Emelianenko, N
Fessia, P
Hagen, P
Miles, J
de Rijk, G
Rossi, L
Todesco, E
Vlogaert, J
Völlinger, C
Wildner, E
Quality Control Techniques Applied to the Large Scale Production of Superconducting Dipole Magnets for LHC
The LHC accelerator, under construction at CERN, is characterized by the use on a large scale of high field superconducting dipoles: the 27-km ring requires 1232 15-m long dipole magnets designed for a peak field of 9 T. The coils are wound with Rutherford-type cable based on copper-stabilized Nb-Ti superconductors and will be operated at 1.9 K in pressurized superfluid helium. The challenge that had to be faced has been an efficient, cost-effective and reproducible mass production to very tight tolerances: the field quality must be better than 10-4 and the geometry of the cold bore tube and magnet controlled to 0.1 mm over the whole length, any deviation being liable to induce delays and significant cost increase. This paper presents the main methods and tools chosen to face successfully this challenge: some methods were foreseen in the technical specification, others were implemented based on the experience gained in several years of fabrication.
eng
CERN;
LHC;
controls;
dipole;
target;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-964;
https://accelconf.web.cern.ch/e06/PAPERS/MOPLS015.PDF;
http://cds.cern.ch/record/977786/files/lhc-project-report-964.pdf;
Imported from Invenio.
Bozzini, D
Caspers, Friedhelm
Chareyre, V
Duse, Y
Kroyer, T
López, R
Poncet, A
Russenschuck, Stephan
Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling
Several methods for electrical fault location have been developed and tested. As part of the electrical quality assurance program for the LHC, certain wires have to be subjected to a (high) DC voltage for the testing of the insulation. With the time difference of spark-induced electromagnetic signals measured with an oscilloscope, fault localization within ± 10 cm has been achieved. Another method used, and adapted for particular needs, is the synthetic pulse time-domain reflectometry (TDR) with a vector network analyzer (VNA). This instrument has also been applied as a low frequency sweep impedance analyzer in order to measure fractional capacitances of cable assemblies where TDR was not applicable.
eng
LHC;
cryogenics;
diagnostics;
impedance;
superconducting-magnet;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-963;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS099.PDF;
http://cds.cern.ch/record/977784/files/lhc-project-report-963.pdf;
Imported from Invenio.
Bozzini, D
Chareyre, V
Kotarba, A
Mess, Karl Hubert
Olek, S
Russenschuck, Stephan
Experience with the Quality Assurance of the Superconducting Electrical Circuits of the LHC Machine
The coherence between the powering reference database for the LHC and the Electrical Quality Assurance (ELQA) is guaranteed on the procedural level. However, a challenge remains the coherence between the database, the magnet test and assembly procedures, and the connection of all superconducting circuits in the LHC machine. In this paper, the methods, tooling, and procedures for the ELQA during the assembly phase of the LHC will be presented in view of the practical experience gained in the LHC tunnel. Some examples of detected polarity errors and electrical non-conformities will be presented. The parameters measured at ambient temperature, such as the dielectric insulation of circuits, will be discussed.
eng
LHC;
dipole;
octupole;
pick-up;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-962;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS098.PDF;
http://cds.cern.ch/record/977782/files/lhc-project-report-962.pdf;
Imported from Invenio.
Ostojic, R
Canard, P
Catalán Lasheras, N
Kirby, G
Perez, JC
Prin, H
Venturini-Delsolaro, W
The Construction of the Superconducting Matching Quadrupoles for the LHC Insertions
After several years of effort, the construction of the superconducting matching quadrupoles for the LHC insertions is nearing completion. We retrace the main events of the project from the initial development of the quadrupole magnets of several types to the series production of over 100 complex superconducting magnets, and report on the techniques developed for steering of the production. The main performance parameters for the full series, such as quench training, field quality and magnet geometry are presented. The experience gained in the production of these special superconducting magnets is of considerable value for further development of the LHC insertions.
eng
CERN;
LHC;
alignment;
insertion;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-961;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS102.PDF;
http://cds.cern.ch/record/977781/files/lhc-project-report-961.pdf;
Imported from Invenio.
Claudet, S
Design, Construction, Installation and First Commissioning Results of the LHC Cryogenic System
The cryogenic system of the Large Hadron Collider (LHC) will be, upon its completion in 2006, the largest in the world in terms of refrigeration capacity with an equivalent to 144 kW at 4.5 K, about 400'000 litres of superfluid helium with 25 km of superconducting magnets below 2 K leading to a cryogen inventory of 100 tons of helium. The challenges involved in the design, construction and installation, as well as the first commissioning results will be addressed in this talk. Particular mention will be made of the problems encountered and how they were or are being solved. Perspectives for LHC will be presented. General considerations for future large cryogenic systems will be briefly proposed.
eng
CERN;
LHC;
collider;
controls;
cryogenics;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-960;
https://accelconf.web.cern.ch/e06/PAPERS/FRXCPA01.PDF;
http://cds.cern.ch/record/977780/files/lhc-project-report-960.pdf;
Imported from Invenio.
Devred, Arnaud
Auchmann, Bernard
Boncompagni, Yann
Ferapontov, V
Koutchouk, Jean-Pierre
Russenschuck, Stephan
Sahner, T
Völlinger, C
First Computation of Parasitic Fields in LHC Dipole Magnet Interconnects
The Large Hadron Collider (LHC), now under construction at CERN, will rely on about 1600 main superconducting dipole and quadrupole magnets and over 7400 superconducting corrector magnets distributed around the eight sectors of the machine. Each magnet type is powered by dedicated superconducting busbars running along the sectors and mounted on the iron yokes of the main dipole and quadruple magnets. In the numerous magnet interconnects, the busbars are not magnetically shielded from the beam pipes and produce parasitic fields that can affect beam optics. We review the 3-D models that have been developed with ROXIE to compute the parasitic fields and we discuss their potential impacts on machine performance.
eng
CERN;
LHC;
dipole;
multipole;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-978;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS101.PDF;
http://cds.cern.ch/record/977801/files/lhc-project-report-978.pdf;
Imported from Invenio.
Tortschanoff, Theodor
Burgmer, R
Durante, M
Hagen, P
Klein, U
Krischel, D
Modena, M
Payn, A
Rossi, L
Sanfilippo, S
Schellong, B
Schirm, KM
Schmidt, P
Simon, F
Todesco, E
Wildner, E
Performance of the LHC Arc Superconducting Quadrupoles Towards the End of their Series Fabrication
The fabrication of the 408 main arc quadrupole magnets and their cold masses will come to an end in summer 2006. A rich collection of measurement and test data has been accumulated and their analysis is presented in this paper. These data cover the fabrication and the efficiency in the use of the main components, the geometrical measurements and the achieved dimensional precision, the warm magnetic measurements in the factory and the performance at cold conditions, especially the training behaviour. The scrap rate of the Nb-Ti/Cu conductor as well as that of other components turned out to be acceptably low and the quench performance measured was in general very good. Most quadrupoles measured so far exceeded the operating field gradient with one or no quench. The multipole content at cold was measured for a limited number of quadrupoles in order to verify the warm-to-cold correlation. From the point of view of field quality, all quadrupoles could be accepted for the machine. The measures taken to overcome the problem of a too high permeability of a batch of collars are discussed.
eng
CERN;
LHC;
dipole;
factory;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-977;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS105.PDF;
http://cds.cern.ch/record/977800/files/lhc-project-report-977.pdf;
Imported from Invenio.
De Rijk, Gijsbert
Piekarz, Henryk
Rossi, Lucio
Preliminary Study of Using "Pipetron-type" Magnets for a Pre-accelerator for the LHC
One of the luminosity limitations of the LHC is the rather low injection energy (0.45 TeV) with respect to the collision energy (7 TeV). The magnetic multipoles in the main dipoles at low field and their dynamic behaviour are considered to limit the achievable bunch intensity and emittance. We report on a preliminary study to increase the injection energy to 1.5 TeV using a two-beam pre-accelerator (LER) in the LHC tunnel. The LER is based on âﾜPipetronâ magnets as originally proposed for the VLHC. The aim of the study is to assess the feasibility and to identify the critical processes or systems that need to be investigated and developed to render such a machine possible.
eng
LHC;
SPS;
dipole;
injection;
lattice;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-976;
https://accelconf.web.cern.ch/e06/PAPERS/TUPLS005.PDF;
http://cds.cern.ch/record/977799/files/lhc-project-report-976.pdf;
Imported from Invenio.
Scandale, Walter
LHC Luminosity and Energy Upgrade
LHC upgrade studies are ongoing as part of the EU CARE-HHH and of the US-LARP programmes. The aim is a ten-fold increase of the LHC luminosity by the middle of next decade, a possible upgrade of the injector complex to inject at 1 TeV and, at a later stage, to raise the collider energy. The motivations for the LHC upgrade are discussed. An overview of beam dynamics and technological challenges is presented. Preferred scenarios to maximize the integrated luminosity and the physics reach are identified.
eng
LHC;
SPS;
dipole;
injection;
luminosity;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-975;
https://accelconf.web.cern.ch/e06/PAPERS/TUXPA03.PDF;
http://documents.cern.ch/archive/electronic/other/uploader/CARE/Conf/care-conf-06-022.pdf;
http://cds.cern.ch/record/977798/files/care-conf-06-022.pdf;
http://cds.cern.ch/record/977798/files/lhc-project-report-975.pdf;
Imported from Invenio.
De Rijk, Gijsbert
Bajko, Marta
Bottura, Luca
Buzio, Marco Carlo Luigi
Chohan, Vinod
Deniau, Laurent
Fessia, Paolo
García-Pérez, Juan
Hagen, Per
Koutchouk, Jean-Pierre
Kozak, Janusz
Miles, John
Missiaen, Dominique Pierre
Modena, Michele
Pugnat, Pierre
Remondino, Vittorio
Rossi, Lucio
Sanfilippo, Stephane
Savary, Frederic
Siemko, Andrzej Piotr
Smirnov, Nikolay
Stafiniak, Andrzej
Todesco, Ezio
Tommasini, Davide
Vlogaert, Jos
Völlinger, Christine
Walckiers, Louis
Wildner, Elena
Performance of LHC Main Dipoles for Beam Operation
At present about 90% of the main dipoles for the LHC have been manufactured and one of the three cold mass assemblers has already completed the production. 85% of the 1232 dipoles needed for the tunnel have been tested and accepted. In this paper we mainly deal with the performance results: the quench behaviour, the magnetic field quality, the electrical integrity quality and the geometry features will be summarized.
eng
CERN;
LHC;
controls;
dipole;
target;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-974;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS100.PDF;
http://cds.cern.ch/record/977797/files/lhc-project-report-974.pdf;
Imported from Invenio.
Koutchouk, Jean-Pierre
Investigations of the Parameter Space for the LHC Luminosity Upgrade
Increasing the LHC luminosity by a factor of ten is a major challenge, especially for the beam-beam long-range interactions and even more for the magnet technology and insertion layout. To help identifying consistent solutions in this multi-dimensional constrained space, a parametric model of an LHC insertion was prepared, based on the present LHC layout, i.e. ?quadrupole first? and small crossing angle. The model deals with the layout, beam optics, beam-beam effect, superconductor margin and peak heat deposition in the coils. The approach is simplified to obtain a large gain in the optimization time. This study puts in evidence, as critical for the luminosity upgrade, the following actions: enlarging significantly the quadrupole aperture, moving the insertion towards the interaction point, using the highest available critical field superconductors and complementing the insertion with an early separation scheme. The luminosity reach can then be extended to 2×1035 cm-2s-1 while 1×1035 can be obtained with significantly reduced requirements (lower beam currents, simpler RF system?).
eng
LHC;
insertion;
luminosity;
quadrupole;
separation-scheme;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-973;
https://accelconf.web.cern.ch/e06/PAPERS/MOPLS011.PDF;
http://documents.cern.ch/archive/electronic/other/uploader/CARE/Conf/care-conf-06-034.pdf;
http://cds.cern.ch/record/977796/files/care-conf-06-034.pdf;
http://cds.cern.ch/record/977796/files/lhc-project-report-973.pdf;
Imported from Invenio.
Koutchouk, Jean-Pierre
Sterbini, G
An Early Beam Separation Scheme for the LHC Luminosity Upgrade
The high nominal luminosity of the LHC requires a large number of bunches spaced by about 7.5 m. To prevent more than one head-on collision in each interaction region, a crossing angle of 0.285 mrad is necessary. A side effect of this crossing angle is the increase of the effective transverse beam cross-section, thereby decreasing the luminosity by some 16%. For the LHC luminosity upgrade, depending on the focusing scenarios, this loss significantly increases and largely offsets the potential gain of a stronger focusing. In this paper we analyze a strategy to circumvent this difficulty, based on an early beam separation using small dipoles placed at a few meters from the interaction point. From the beam dynamics point of view, the essential constraint is to control the long-range beamâbeam interactions in a scenario where the normalized beam separation is not constant.
eng
LHC;
beam-beam-effects;
dipole;
luminosity;
separation-scheme;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-972;
https://accelconf.web.cern.ch/e06/PAPERS/WEPCH094.PDF;
http://documents.cern.ch/archive/electronic/other/uploader/CARE/Conf/care-conf-06-033.pdf;
http://cds.cern.ch/record/977795/files/care-conf-06-033.pdf;
http://cds.cern.ch/record/977795/files/lhc-project-report-972.pdf;
Imported from Invenio.
Hagen, P
Giovannozzi, Massimo
Koutchouk, Jean-Pierre
Risselada, Thys
Sanfilippo, S
Todesco, E
Wildner, E
WISE: An Adaptative Simulation of the LHC Optics
The beam dynamics in LHC requires a tight control of the field quality and geometry of the magnets. As the production advances, decisions have to be made on the acceptance of possible imperfections. To ease decision making, an adaptative model of the LHC optics has been built, based on the information available on the day (e.g. magnetic measurements at warm or cold, magnet allocation to machine slots) as well as on statistical evaluations for the missing information (e.g. magnets yet to be built, measured, or for non-allocated slots). The uncertainties are included: relative and absolute measurement errors, warm-to-cold correlations for the fraction of magnets not measured at cold, hysteresis and power supply accuracy. The pre-processor WISE generates instances of the LHC field errors for the MAD-X program, with the possibility of selecting various sources. We present an application to estimate the expected beta-beating.
eng
CERN;
LHC;
power-supply;
quadrupole;
simulation;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-971;
https://accelconf.web.cern.ch/e06/PAPERS/WEPCH139.PDF;
http://cds.cern.ch/record/977794/files/lhc-project-report-971.pdf;
Imported from Invenio.
Laface, E
Ostojic, R
Santoni, C
Scandale, Walter
Tommasini, D
Interaction Region with Slim Quadrupoles
An optical performance's improvement of the interaction region can be obtained with the addition of new quadrupoles in the forward detectors area. Such scenario would allow decreasing the ß* below the nominal value.The basic concept consists in using quadrupoles to break the quadratic behavior of ß in the free space between the IP and the IR triplets.I In this new configuration we present the performance improvements and the hardware requirements.
eng
LHC;
beam-beam-effects;
interaction-region;
luminosity;
quadrupole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=lhcproj-2006-970;
https://accelconf.web.cern.ch/e06/PAPERS/WEPCH044.PDF;
http://documents.cern.ch/archive/electronic/other/uploader/CARE/Conf/care-conf-06-035.pdf;
http://cds.cern.ch/record/977793/files/care-conf-06-035.pdf;
http://cds.cern.ch/record/977793/files/lhc-project-report-970.pdf;
Imported from Invenio.
Auchmann, Bernard
de Maria, Riccardo
Russenschuck, Stephan
Comparative Study of Inter-Strand Coupling Current Models for Accelerator Magnets
Inter-strand coupling currents (ISCCs) contribute to field errors and losses in Rutherford-type superconducting cables in the time-transient regime. A field change induces eddy currents in loops formed by the superconducting twisted strands and the resistive matrix. The implementation of ISCC models in ROXIE allows to combine ISCC calculations with models for persistent current sand inter- filament coupling currents. Saturation effects in iron can be taken into account as well. The predictions of different ISCC models with regard to losses and field errors are compared for two design versions of the LHC main dipole.
eng
CERN;
GSI;
LHC;
coupling;
dipole;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=at-2006-011;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS107.PDF;
http://cds.cern.ch/record/978045/files/at-2006-011.pdf;
Imported from Invenio.
Bellesia, B
Santoni, C
Todesco, E
Random Errors in Superconducting Dipoles
The magnetic field in a superconducting magnet is mainly determined by the position of the conductors. Hence, the main contribution to the random field errors comes from random displacement of the coil with respect to its nominal position. Using a Monte-Carlo method, we analyze the measured random field errors of the main dipoles of the LHC, Tevatron, RHIC and HERA projects in order to estimate the precision of the conductor positioning reached during the production. The method can be used to obtain more refined estimates of the random components for future projects.
eng
LHC;
RHIC;
dipole;
multipole;
simulation;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=at-2006-010;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS097.PDF;
http://cds.cern.ch/record/978044/files/at-2006-010.pdf;
Imported from Invenio.
Fiorini, Massimiliano
Ambrosi, Giovanni
Assmann, Ralph Wolfgang
Biino, Cristina
Chesnokov, Yuri
Dalpiaz, Pietro
Efthymiopoulos, Ilias
Gatignon, Laurent
Guidi, Vincenzo
Ivanov, Yuri M
Santacesaria, Roberta
Scandale, Walter
Taratin, Alexander Mihailovich
Vomiero, Alberto
Experimental Study of Crystal Channelling at CERN-SPS for Beam-Halo Cleaning
An efficient and robust collimation system is mandatory for any superconducting hadron collider, in particular for the LHC, which will store a beam of unprecedented high intensity and energy. The usage of highly efficient and short primary bent-crystal collimators might be a possibility for reaching nominal and ultimate LHC intensity. Over the last years, groups in Italy (Ferrara) and Russia (St. Petersburg) have developed crystal production methods, that considerably improve the crystal quality. These developments led, in turn, to a surprising increase in the channeling efficiency and to the recent observation of the âﾜvolume reflectionâ mechanism. The aim of the proposed experiment is the setup of a beam test facility, directing primary protons from the SPS onto a bent silicon crystal, and the quantitative study of single-pass efficiency for all involved processes. Final goal will be the extrapolation of important information on the feasibility of a crystal collimator for halo cleaning in the LHC. The experiment will be performed in the H8 beamline at the CERN SPS where a beam with very small divergence can be provided thus representing a unique facility for tests and characterization of crystals to be used for particle channeling studies.
eng
LHC;
SPS;
alignment;
collimation;
proton;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=at-2006-009;
https://accelconf.web.cern.ch/e06/PAPERS/TUPLS022.PDF;
http://cds.cern.ch/record/978043/files/at-2006-009.pdf;
Imported from Invenio.
Guidi, V
Baricordi, S
Boscolo-Marchi, E
Carnera, A
Chesnokov, Yu A
Della Mea, G
De Salvador, D
Fiorini, M
Ivanov, Y M
Martinelli, G
Mazzolari, A
Milan, E
Milan, R
Sambo, A
Scandale, Walter
Todros, S
Vomiero, A
Characterization of Crystals for Steering of Protons through Channelling in Hadronic Accelerators
Channeling of relativistic particles through a crystal may be useful for many applications in accelerators, and particularly for collimation in hadronic colliders. Efficiency proved to be dependent on the state of the crystal surface and hence on the method used for preparation. We investigated the morphology and structure of the surface of the samples that have been used in accelerators with high efficiency. We found that crystal fabrication by only mechanical methods (dicing, lapping, and others) leads to a superficial damaged layer, which is correlated to performance limitation in accelerators. A planar chemical etching was studied and applied in order to remove the superficial damaged layer. RBS channeling analysis with low-energy protons and 4He+ highlighted better crystal perfection at surface, as a result of the etching. A protocol for preparation and characterization of crystal for channelling has been developed, which may be of interest for reliable operation with crystals in accelerators.
eng
CERN;
extraction;
lattice;
proton;
scattering;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=at-2006-008;
https://accelconf.web.cern.ch/e06/PAPERS/TUPLS016.PDF;
http://cds.cern.ch/record/978042/files/at-2006-008.pdf;
Imported from Invenio.
After a major coil insulation breakdown on two of the 47-year-old CERN PS main magnets in 2003, an extensive magnet consolidation program has been launched. This article reviews the analysis of the magnet state be-fore the repair and the applied major improvements. An overview is given of the production of the new compo-nents, the actual refurbishment and the commissioning of the main magnet system after 18 months shutdown.
eng
CERN;
LHC;
radiation;
radioactivity;
vacuum;
2006
http://documents.cern.ch/cgi-bin/setlink?base=preprint&categ=cern&id=at-2006-006;
https://accelconf.web.cern.ch/e06/PAPERS/WEPLS083.PDF;
http://cds.cern.ch/record/977803/files/at-2006-006.pdf;
Imported from Invenio.