Gyr, M Goddard, B Jeanneret, Jean Bernard Ramberger, S Septum Magnets, MSD, LBDS, Extraction 2006 2006 An analogous strategy as applied for the MSI septum magnets allows an optimisation of the installation of the MSD septa regarding magnet and chamber allocation. Even if the gain in aperture is small, of the order of half a millimetre, it is not negligible and- being essentially for free - should nevertheless be implemented. Henrist, Bernard Jiménez, J M Lacroix, Jean Michel Sgobba, Stefano Gyr, Marcel 2005 2005 Each beam arriving from the SPS has to pass through five injection septum magnets before being kicked onto the LHC orbit. The injection layout implies that the vacuum chambers for the two circulating beams pass through the septum magnet yokes at a flange distance from the chamber of the beam to be injected. Specially designed vacuum chambers and interconnections provide the required straightness and alignment precision, thus optimising the aperture for both the circulating and injected beams, without affecting the quality of the magnetic dipole field seen by the injected beam. The circulating beams are shielded against the magnetic stray field by using µ-metal chambers with a thickness of 0.9 mm to avoid saturation of the µ-metal (0.8 T), coated with copper (0.4 mm) for impedance reasons and NEG for pumping and electron cloud purposes. A 2 mm gap between the iron yoke and the µ-metal chamber allows an in-situ bake-out at 200°C, based on a polyimide/stainless steel/polyimide sandwich structure with an overall thickness of 0.2 mm. The constraints are described and the resulting vacuum system design, the apertures and the residual stray field are presented in this paper. Filippini, R Goddard, B Gyr, Marcel Kain, V Schmidt, R Uythoven, J Wenninger, J 2004 2004 The LHC machine protection systems, including the beam dumping system, are designed to ensure that failures leading to serious damage to the LHC during its lifetime are extremely unlikely. These kind of failures, for instance requiring a combination of equipment failure and surveillance failure, have to date been considered as being 'beyond the design case'. However, their consequences need to be evaluated to determine the required safety levels of the protection systems. A second objective is to understand if measures can and should be taken to further reduce the probability of such failures, or to minimise their impact. This paper considers various serious failure modes of the different machine protection systems. The probable consequences and possible ameliorating measures of the worst-case scenarios are discussed. The particular case of having a stored beam with an unavailable beam dumping system is mentioned, together with possible actions to be taken in such an event. Goddard, B Gyr, Marcel Jeanneret, J B Kain, V Lamont, M Maire, V Mertens, V Wenninger, J 2004 2004 The main LHC injection elements in interaction regions 2 and 8 comprise the injection septa (MSI), the injection kickers (MKI), together with three families of passive protection devices (TDI, TCDD and TCLI). The apertures of the two circulating beams are detailed for these elements, together with a summary of recent design modifications. The errors in the SPS, the transfer lines and the injection system are analysed, and the expected performance of the system derived, in terms of the expected delivery precision of the injected beam. Goddard, B Gyr, Marcel Kain, V Risselada, Thys 2004 2004 Skew quadrupoles are well known for their capability of tilting beams around their longitudinal axes. However, dipoles can produce the same effect. A horizontal bending dipole aligned with an inclination (slope) angle phi with respect to the reference coordinate system introduces a small tilt (roll) angle psi into the beam, which for small angles is proportional to the product of the magnet bending angle alpha and the slope phi. For transfer lines this effect has previously been neglected (it is comparable to the tilt alignment tolerance of the magnets of the order of 0.1 mrad rms), but for long lines with many horizontal bending magnets on relatively steep vertical slopes relative to the reference frame, a non-negligible tilt angle psi can accumulate between the local beam plane and the reference alignment system. This can result in mismatch at injection with subsequent emittance blow-up, and other undesirable effects, such as non-orthogonal trajectory measurement and correction. A detailed description of this effect is given, illustrated by the SPS to LHC transfer lines TI 8 and the LHC machine itself. The implications and the resulting choice of methodology for alignment of the elements along the line are described and a solution for matching to the plane of the LHC is outlined. Goddard, B Gyr, Marcel Beam Dumping System, Extraction Septum, Aperture 2003 2003 The LHC beam dumping system must safely abort the LHC beams over the whole energy range, under all realistically possible fault conditions. These include normal operation, failure of machine elements and also abnormal performance of subsystems of the beam dumping system itself. To avoid unnecessary irradiation and even equipment damage, the MSD extraction septa must provide sufficient aperture both for the circulating and extracted beams. In order to satisfy this requirement, a modified (enlarged) vacuum chamber design will be used for the limiting MSDC septa. The analysis of the available apertures is presented, with emphasis on the dependence on the local orbit and beam emittance. Gyr, M Uythoven, J Veness, R Weterings, W Goddard, B 2003 2003 The LHC beam dumping system must safely abort the LHC beams under all conditions, including those resulting from abnormal behaviour of machine elements or subsystems of the beam dumping system itself. The extraction channels must provide sufficient aperture both for the circulating and extracted beams, over the whole energy range and under various beam parameters. These requirements impose tight constraints on the tolerances of various extraction channel components, and also on the allowed range of beam positions in the region of these components. Operation of the beam dumping system under various fault states has been considered, and the resulting apertures calculated. After describing briefly the beam dumping system and the extraction channel geometry, the various assumptions made in the analysis are presented, before deriving tolerance limits for the relevant equipment and beam parameters. Bidon, S Gerard, D Guinand, M Gyr, Marcel Sassowsky, M Weisse, E Weterings, W Abramov, A Ivanenko, A I Kolatcheva, E Lapyguina, O Ludmirsky, E Mishina, N Podlesny, P Riabov, A Tyurin, N septum magnet-design injection extraction 2002 2002 The Large Hadron Collider (LHC) will be a superconducting accelerator and collider to be installed in the existing underground LEP ring tunnel at CERN. It will provide proton-proton collisions with a centre of mass energy of 14 TeV. The proton beams coming from the SPS will be injected into the LHC at 450 GeV by vertically deflecting kicker magnets and horizontally deflecting steel septum magnets (MSI). The proton beams will be dumped from the LHC with the help of two extraction systems comprising horizontally deflecting kicker magnets and vertically deflecting steel septum magnets (MSD). The MSI and MSD septa are laminated iron-dominated magnets using an all welded construction. The yokes are constructed from two different half cores, called coil core and septum core. The septum cores comprise circular holes for the circulating beams. This avoids the need for careful alignment of the usually wedge-shaped septum blades used in classical Lambertson magnets. The MSI and MSD septum magnets were designed and built in a collaboration between IHEP (Protvino) and CERN (Geneva). This paper presents the magnet design, the experience gathered during the preseries construction, and gives the results of detailed magnetic measurements of the MSIB and MSDC preseries magnets. Drozhdin, A I Gyr, Marcel Mokhov, N V Rakhno, I L Weisse, E 2001 2001 The effect of possible accidental beam loss in the LHC on the IP5 and IP6 insertion elements is studied via realistic Monte Carlo simulations. The scenario studied is beam loss due to unsynchronized abort at an accidental prefire of one of the abort kicker modules. Simulations show that this beam loss would result in severe heating of the IP5 and IP6 superconducting (SC) quadrupoles. Contrary to the previous considerations with a stationary set of collimators in IP5, collimators in IP6 close to the cause are proposed: a movable collimator upstream of the Q4 quadrupole and a stationary one upstream of the extraction septum MSD. The calculated temperature rise in the optimal set of collimators is quite acceptable. All SC magnets are protected by these collimators against damage. Gyr, Marcel Beam Dump Extraction Injection MSD MSI Septum magnets Shielding 2000 2000 Computation of the residual field inside the shielded vacuum chambers of the circulating beams that pass through the septum holes of the MSI and MSD magnets is very impractical because of the disproportionate effort involved in obtaining meaningful results. Therefore, a short model has been built to measure the order of magnitude of the residual field inside the LHC vacuum chambers. It is found, that a 0.9 mm thick µ-metal (or Permalloy$^{TM}$) shielding is sufficient to reduce the field, which is experienced by the circulating beam, below the level of the earth's field. Gyr, Marcel Beam Dump Extraction Injection MSD MSI Septum Magnets 1998 1998 Goddard, B Gyr, Marcel algorithms bumper extraction fast kicker resonant septa 1998 1998 SICOPEX is a System for Interactive Computation of Optimum Extractions. The program computes the septa positions, the kicker, bumper and septa strengths for a set of several extractions through the same extraction channel in the SPS long straight sections LSS2 or LSS6. These quantities are computed such as to maximise the relative gain of required clearances at the entrance of the electrostatic and magnetic septa. These extractions can be of different type (resonant or fast, including fast shaving) and at different energies. The first part of this paper describes the formulation of the extraction problem and the algorithm that is used to solve it. The second part explains the structure of the SICOPEX package, and gives details of how to run SICOPEX on a Windows PC. Elsener, K Fidecaro, Giuseppe Gyr, Marcel Herr, Werner Klem, J T Mikkelsen, U Weisse, E 1998 1998 The feasibility and properties of particle extraction from an accelerator by means of a bent crystal were studied extensively at the CERN SPS. The main results of the experiments are presented. This includes the evidence for multipass extraction of heavy ions. These results are compared with theoretical expectations and computer simulations. Arduini, Gianluigi Elsener, K Fidecaro, Giuseppe Gyr, Marcel Herr, Werner Klem, J T Mikkelsen, U Weisse, E Phys. Lett. B 10.1016/S0370-2693(98)00132-4 325 422 1/4 1998 1998 Proton beam extraction from the CERN SPS by means of a bent silicon crystal is reported at three different energies, 14 GeV, 120 GeV and 270 GeV. The experimental results are compared to computer simulations which contain a sound model of the SPS accelerator as well as the channeling phenomena in bent crystals. The overall energy dependence of crystal assisted proton beam extraction is understood and provides the basis to discuss such a scheme for future accelerators. Arduini, Gianluigi Cornelis, Karel Elsener, K Ferioli, G Fidecaro, Giuseppe Gyr, Marcel Herr, Werner Klem, J T Weisse, E 1998 1998 The extraction of protons from the halo of a circulating beam has been repeatedly demonstrated at the SPS. In a recent experiment a coasting lead ion beam was available at a momentum of 270 GeV/c per charge corresponding to a total momentum of 22 TeV/c per ion and the possibility to extract ultrarelativistic lead ions with a bent crystal could be demonstrated for the first time. We present the experimental challenges, the measurements performed during this experiment and the first results. Arduini, Gianluigi Elsener, K Fidecaro, Giuseppe Gyr, Marcel Herr, Werner Klem, J T Mikkelsen, U Weisse, E 1998 1998 The feasibility of extracting particles from the halo of a circulating beam has been successfully demonstrated in an experiment at the SPS. Although most measurements were obtained at an intermediate energy of 120 GeV, more recently we had the opportunity to extract protons from a coasting beam at 14 GeV and 270 GeV, thus exploiting the full available energy range of the SPS. In this report we present a comparison of the measurements at the three energies and a qualitative comparison with the predictions. Gyr, Marcel 1997 1997 Two-dimensional fields in regions with constant material properties (magnetic permeability, dielectric permittivity, heat conductivity, etc.) can be derived from a complex potential function W, where the real and imaginary parts correspond to the scalar potential function F and the stream function Y respectively. In source-free regions (no currents, electric charges, heat sinks, etc.), the field, is conservative and its complex potential W is a harmonic function where F and Y satisfy the Laplace equation. In such regions W can be expressed as a power series, the coefficients of which being the, multipole components of the field with respect to the origin of the series expansion. This note describes how these multipole coefficients are related to the amplitudes and phase angles as computed by, FLUX2D in the spectrum analysis of the magnetic vector potential. In the case of electrical or thermal problems, these same considerations apply by analogy. Arduini, Gianluigi Biino, C Clément, M Cornelis, Karel Doble, Niels T Elsener, K Ferioli, G Fidecaro, Giuseppe Freund, A Gatignon, L Grafström, P Gyr, Marcel Herr, Werner Keppler, P Klem, J T Major, J V Mikkelsen, U Møller, S P Taratin, A M Uggerhøj, Erik Weisse, E Phys. Rev. Lett. 10.1103/PhysRevLett.79.4182 4182-4185 79 1997 1997 The first results from an experiment to deflect a beam of fully stripped, ulta-relativistic Pb ions of 400 GeV/c per unit of charge, equivalent to 33 TeV/c, by means of a bent crystal are reported. Deflection efficiencies are as high as 14%, in agreement with theoretical predictions. In a second experiment a bent crsytal was used to extract 270 GeV/c per charge Pb82+ (22 TeV/c) ions from a coasting beam in the CERN-SPS, and a high extraction efficiency of up to 10% was found. These represent the first measurements to demonstrate applications of bent crystals in high energy heavy ion beams. Ferrari, A Gyr, M CERN-SPS&LHC advanced-extraction crystal-channeling 1996 Ferrari, A Gyr, M CERN-SPS&LHC advanced-extraction crystal-channeling 1996 Gyr, Marcel Ferrari, A CERN SPS and LHC advanced-extraction crystal-channeling 1996 1996 A laser scan was performed with the new U-shaped crystal G5, which has a known miscut of +1 mrad and is installed at the upstream position #1 in the TEC. The aim was to cross-check the angular sensitivity of the stepping motor of the goniometer, which theoretically should be 1.98 µrad/step. Gyr, M CERN-SPS extraction-equipment servo-spill 1995 1995 Elsener, K Fidecaro, G Gyr, M Herr, W Klem, J Mikkelson, U Weisse, E CERN-SPS advanced-extraction crystal-channeling 1995 1995 Gyr, M Halvarsson, B Klem, J Louwerse, R Milstead, I CERN-LEP advanced-extraction crystal-channeling 1995 Gyr, M Stevenson, G R Weisse, E Zazula, J M CERN-LHC beam-dumps 1995 1995 Bussa, M P Carboni, G Dehning, B Elsener, K Fidecaro, G Freund, A Gyr, M Herr, W Hustache, R Klem, J Møller, S P Scandale, W Tosello, F Uggerhøj, E Vuagnin, G Weisse, E Weisz, S CERN-SPS&LEP advanced-extraction crystal-channeling 1995 1995 Altuna, X Dehning, B Elsener, K Ferrari, A Fidecaro, G Guinand, R Gyr, M Herr, W Laffin, M Scandale, W Weisse, E Weisz, S CERN-SPS&LEP advanced-extraction crystal-channeling 1995 1995 Gyr, Marcel Halvarsson, Bjorn Klem, J T Louwerse, R Milstead, I CERN LEP advanced-extraction crystal-channeling 1995 1995 The analogue noise signal produced by a WAVETEK function generator, which is used to excite one of the horizontal dampers BDH 21437 or BDH 21451 for blowing up the beam during the crystal extraction MDs, has been analysed to determine its r.m.s. value as a function of the selected attenuation. The input/output characteristics of damper Nº 2 (BDH 21451) has been measured in order to calibrate the r.m.s. kicks (diffusion speed) which a particle experiences on its passage through the damper. Gyr, Marcel 1995 1995 Elsener, K Fidecaro, Giuseppe Gyr, Marcel Herr, Werner Klem, J T Mikkelsen, U Weisse, S P Møller, S P Uggerhøj, Erik Vuagnin, G 1995 1995 The extraction of high energy particles from a circular accelerator by means of channeling in bent crystals is an attractive alternative to classical extraction schemes, in particular for high energy proton colliders where a classical scheme becomes expensive and incompatible with normal operation this paper reviews the ongoing extraction experiments at the CERN-SPS with bent silicon crystals. it describes the principles of beam extraction by means of a bent crystal and the different extraction schemes used: firs- and multi-pass extraction and the methods to create diffusion. The limitations in tuning the accelerator to the desired impact parameters and crucial items concerning crystal preparation, bending and pre-alignment are discussed. the experimental procedures including an overview of the detection of circulation and extracted beam are given. Finally the paper summarizes the results of these experiments together with ideas for future developments. Zazula, J M Gyr, Marcel Stevenson, Graham Roger Weisse, E 1996 1996 Recent Monte Carlo cascade simulations have shown that a reduction in the maximum of deposited energy density can be obtained by applying a uniform magnetic field over a front part of the graphite core of the LHC dump. This paper shows the effect of field strength on spatial distributions of absorbed energy and temperatures, and discusses problems to be solved when designing a suitable magnet. Altuna, X Bussa, M P Carboni, G Dehning, Bernd Elsener, K Ferrari, A Fidecaro, Giuseppe Freund, A Guinand, R Gyr, Marcel Herr, Werner Klem, J T Laffin, M Lanceri, L Mikkelsen, U Møller, S Scandale, Walter Tosello, F Uggerhøj, Erik Vuagnin, G Weisse, E Weisz, S Phys. Lett. B 10.1016/0370-2693(95)00981-P 671-677 357 1995 1995 Recent measurements of 120GeV proton extraction by means of a bent silicon cryt the CERN-SPS accelerator are summarized. The existence of multi-pass extraction has been proven by blocking first-pass extraction: using a crystal covered with an amorphous layer, extracted beam with high efficiency was observed, which provides a direct proof for the importance of the multi-pass mechanism. This opens new possibilities in the design of a bent crystal extraction for LHC. Dehning, Bernd Elsener, K Fidecaro, Giuseppe Gyr, Marcel Herr, Werner Klem, J T Scandale, Walter Vuagnin, G Weisse, E Weisz, S Møller, S P Uggerhøj, Erik Freund, A Hustache, R Carboni, G Bussa, M P Tosello, F 1996 1996 The feasibility of extracting particles from the halo of a circulating proton beam using a bent silicon crystal has been demonstrated experimentally at the SPS for a beam energy of 120 GeV. Presently studies are conducted to understand the extraction mechanisms and the measured efficiencies. In particular the contribution of multi-pass extraction, where the particles can pass through the crystal many times before being channelled and extracted, is investigated. In a recent experiment, using a crystal especially fabricated with a finite amorphous layer on its surface, it has been proven that multi-pass extraction plays an important role. The experiment is described and the implication for further studies are discussed. Gyr, M CERN-SPS classical-magnets quadrupoles 1994 1994 Gyr, Marcel 1994 1994 Gyr, M CERN-SPS advanced-extraction crystal-channeling 1993 1993 Akbari, H Altuna, X Bardin, S Bellazzini, R Biryukov, V Brez, A Bussa, M P Busso, L Calcaterra, A Carboni, G Costantini, F De Sangro, R Elsener, K Ferioli, F Ferrari, G P Ferri, G P Ferroni, F Fidecaro, G Freund, A Guinand, R Gyr, M Herr, W Hilaire, A Jensen, B N Klem, J Lanceri, L Maier, K Massai, M M Mertens, V Moller, S P Morganti, S Peraire, S Petresa, S Placidi, M Santacesaria, R Scandale, W Schmidt, R Taratin, A M Tosello, F Uggerhoj, E Vettermann, B Vita, P F Vuagnin, G Weisse, E Weisz, S Palamara, O CERN-SPS advanced-extraction crystal-channeling 1993 1993 Gyr, Marcel CERN SPS advanced-extraction crystal-channeling 1993 1993 The proton beam, extracted by a bent crystal, leaves the vacuum chamber through a thin steel window and traverses a series of different detectors. Multiple Coulomb scattering inside these media leads to an increase of the beam size. A simple recursion algorithm has been developed which calculates the angular and spatial dispersion of a particle traversing a cascade of different scatterers, allowing to compute a good estimate of this effect without requiring a time consuming Monte Carlo simulation. Akbari, H Altuna, X Bardin, S Bellazzini, R Biryukov, V M Brez, A Bussa, M P Busso, L Calcaterra, A Carboni, G Costantini, F De Sangro, R Elsener, K Ferioli, F Ferrari, A Ferri, G Ferroni, F Fidecaro, Giuseppe Freund, A Guinand, R Gyr, Marcel Herr, Werner Hilaire, A Jensen, B N Klem, J T Lanceri, L Maier, K Massai, M M Mertens, V Møller, S P Morganti, S Palamara, O Péraire, S Petrera, S Placidi, Massimo Santacesaria, R Scandale, Walter Schmidt, R Taratin, A M Tosello, F Uggerhøj, Erik Vettermann, B Vita, P F Vuagnin, G Weisse, E Weisz, S Phys. Lett. B 10.1016/0370-2693(93)90024-C 491-497 313 1993 1993 Gyr, M CERN-LHC advanced-extraction crystal-channeling 1992 1992 Gyr, Marcel CERN LHC advanced-extraction crystal-channeling 1992 1992 The program CRYSTAL.BAS allows to calculate the exact alignment of the crystal with respect to thebeam. It is written in QBasic and installed on server USRV_865 connected to the PC network. This note describes how to access and to run this program from any PC which is connected to the network NICE. The angle of the two crystals actually installed has been scanned over a relatively wide range and at different positions with respect to the ideal closed orbit, thereafter referred to as beam center line. The signal (Volt) produced by the position sensitive detectors (PSD) intercepting the reflected laser beams used to monitor the crystal alignment, is plotted in the attached figures. Gyr, Marcel Vossenberg, Eugène B 1992 1992 Gyr, M CERN-SPS extraction-theory 1990 1990 Gyr, Marcel algorithms bumper extraction fast kicker manual resonant septa 1990 1990 Gyr, M CERN-SPS extraction-theory spill 1989 1989 Gyr, Marcel CP delay mains noise violation white 1989 1989 Asner, Alfred M Baconnier, Yves Bassetti, Mario Benvenuti, Cristoforo Boussard, Daniel Brandt, Daniel Brianti, Giorgio Calder, Roger Dupin, Jacques Fassò, Alberto Gareyte, Jacques Goebel, Klaus Gröbner, Oswald Guignard, Gilbert Gyr, Marcel Hagedorn, Dietrich Hilaire, Alain Hilleret, Noël Hübner, K Ijspeert, Albert Keil, Eberhard Kissler, Karl Heinz Koutchouk, Jean-Pierre Laurent, Jean Michel Lebrun, P Leroy, Daniel Morpurgo, Mario Perin, Romeo Potter, Keith M Reinhard, Hans Peter Resegotti, Lorenzo Scandale, Walter Schmid, Jörg Schnell, Wolfgang Schröder, Gerhard Stevenson, Graham Roger Thomi, Werner Tortschanoff, Theodor Verdier, André Vos, Lucien Vossenberg, Eugène B Weisse, Eberhard de Rijk, G 10.5170/CERN-1987-005 10-100TeVcm ep luminosity magnets proton proton studies superconducting 1987 1987 Gyr, Marcel conformal dimensional formula mapping two 1986 1986 Gyr, M CERN-SPS magnet-design field-errors 1985 1985 Gyr, M Kissler, K H Pahud, J D Peraire, S CERN-SPS extraction-theory shared-extraction 1985 1985 Gyr, M CERN-SPS classical-magnets quadrupoles 1985 1985 Gyr, Marcel Kissler, Karl Heinz Pahud, J D Péraire, S beams extraction fixed target time 1985 1985 Gyr, Marcel currents damage eddy insulation radiation synchrotron vetronite 1985 1985 Gyr, M Kissler, K H Peraire, S CERN-SPS extraction-theory resonant-extraction 1984 1984 Gyr, M Kissler, K H Péraire, S CERN-LEP extraction-theory 1984 1984 Gyr, Marcel Mikro Klein Comput. 43-44 83 1983 1983 Gyr, M CERN-SPS beam-optics lepton-extraction 1982 1982 Gyr, M CERN-SPS extraction-theory stochastic-RF-noise 1980 1980 Boussard, D Gyr, M Kissler, Karl Heinz Linnecar, T 1980 1980 Gyr, G CERN-SPS extraction-theory extraction-channels 1979 1979 Faugier, A Gyr, Marcel Hatton, V Hilaire, A Lauckner, R Miles, J Péraire, S Thomas, D Warman, A 2 SPS performance slow spills 1980 1980 Describes the most relevant factors that have contributed to the steady improvement in performance of the SPS are a supplier of protons for the high energy physics programme of CERN. The maximum intensity is now 2.7*10/sup 13/ protons per pulse, the slow spills are better and for 90% of the scheduled time the beam is on the targets. (0 refs) . Newman, Wolfgang Simon CERN-SPS classical-magnets bumper-dipoles 1979 1979 Gyr, M 1979 1979 Gyr, M CERN-SPS extraction-theory extraction-channel 1978 1978 Gyr, M CERN-SPS extraction-theory 1978 1978 Gyr, M CERN-SPS beam-observation coupling 1978 1978 Gyr, M Scandale, Walter 1978 1978 Gyr, Marcel 1978 1978 Gyr, M Roedel, V Spinks, A CERN-SPS operation start-up 1977 1977 Gyr, Marcel IEEE Trans. Autom. Contr. 88 19 1974 1974 Weisz, S 1993 1993 Akbari, H Elsener, K 1994 1994