R. Schmidt
CERN
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by R. Schmidt.
New Journal of Physics | 2006
R. Schmidt; R. Assmann; Etienne Carlier; B. Dehning; R Denz; B. Goddard; Eva Barbara Holzer; V. Kain; B. Puccio; B. Todd; J. Uythoven; J. Wenninger; Markus Zerlauth
TheLargeHadronCollider(LHC)atCERNwillcollidetwocounter- rotating proton beams, each with an energy of 7TeV. The energy stored in the superconducting magnet system will exceed 10GJ, and each beam has a stored energy of 362MJ which could cause major damage to accelerator equipment in the case of uncontrolled beam loss. Safe operation of the LHC will therefore rely on a complex system for equipment protection. The systems for protection of the superconducting magnets in case of quench must be fully operational before powering the magnets. For safe injection of the 450GeV beam into the LHC, beam absorbers must be in their correct positions and specific procedures must be applied. Requirements for safe operation throughout the cycle necessitate early detection of failures within the equipment, and active monitoring of the beam with fast and reliable beam instrumentation, mainly beam loss monitors (BLM). When operating with circulating beams, the time constant for beam loss after a failureextendsfrom ≈mstoafewminutes—failuresmustbedetectedsufficiently early and transmitted to the beam interlock system that triggers a beam dump. It is essential that the beams are properly extracted on to the dump blocks at the end of a fill and in case of emergency, since the beam dump blocks are the only elements of the LHC that can withstand the impact of the full beam.
European Physical Journal A | 1995
L. Arnaudon; B. Dehning; P. Grosse-Wiesmann; R. G. Jacobsen; M. Jonker; Jean-Pierre Koutchouk; J. Miles; R. Olsen; Massimo Placidi; R. Schmidt; J. Wenninger; R. Assmann; A. Blondel
To improve the measurements of the Z boson mass and resonance width, the 1993 Large Electron Positron Collider (LEP) run was devoted to a three point beam energy scan, with one point close to the peak of the Z resonance and two points roughly 880 MeV below and above the peak. Operational energy calibration by resonant depolarization was successfully commissioned for all three beam energies. 24 energy calibrations were performed at the end of physics fills. The accuracy of each calibration is better than 1 MeV. About one third of the total integrated luminosity was recorded in calibrated fills below and above the resonance and a regular tracking of the beam energies throughout the scan was possible. The evolution of the beam energies in the course of the year showed a large variation of up to 20 MeV. Results from the energy calibrations will be presented and possible explanations for the changes of the beam energy during the year will be described.
Journal of Applied Physics | 2005
N. A. Tahir; B. Goddard; V. Kain; R. Schmidt; A. Shutov; I. V. Lomonosov; A. R. Piriz; M. Temporal; D. H. H. Hoffmann; V. E. Fortov
The large hadron collider (LHC) will allow for collision between two 7TeV∕c proton beams, each comprising 2808 bunches with 1.1×1011 protons per bunch, traveling in opposite direction. The bunch length is 0.5ns and two neighboring bunches are separated by 25ns so that the duration of the entire beam is about 89μs. The beam power profile in the transverse direction is a Gaussian with a standard deviation of 0.2mm. The energy stored in each beam is about 350MJ that is sufficient to melt 500kg of copper. In case of a failure in the machine protection systems, the entire beam could impact directly onto an accelerator equipment. A first estimate of the scale of damage resulting from such a failure has been assessed for a solid copper target hit by the beam by carrying out three-dimensional energy deposition calculations and two-dimensional numerical simulations of the hydrodynamic and thermodynamic response of the target. This work has shown that the penetration depth of the LHC protons will be between 10 and ...
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1995
L. Arnaudon; B. Dehning; A. Hofmann; P. Grosse-Wiesmann; R. G. Jacobsen; Jean-Pierre Koutchouk; J. Miles; R. Olsen; Massimo Placidi; R. Schmidt; J. Wenninger; R. Assmann; A. Blondel; G.E. Fischer
Abstract The circular e + e − collider LEP located near Geneva is used to investigate the properties of the Z boson. The measurements of the Z boson mass and resonance width are of fundamental importance for the standard model of the electroweak interactions. They require a knowledge of the LEP beam energy with a precision of ∼ 20 ppm, which is provided by a measurement of the electron spin precession frequency. To extrapolate beam energy calibrations over a longer period of time, effects causing energy changes have to be taken into account. Among these are the terrestrial tides due to the sun and moon which move the Earth surface up and down. The lateral components of this motion modify the 26.7 km LEP circumference by about 1 mm. This change in length results in variations of the beam energy up to 120 ppm. We present results of measurements on the influence of terrestrial tides on the LEP beam energy that have been performed in 1992 and 1993.
BEAM HALO DYNAMICS, DIAGNOSTICS, AND COLLIMATION: 29th ICFA Advanced Beam Dynamics Workshop on Beam Halo Dynamics, Diagnostics, and Collimation HALO'03 | 2003
R. Schmidt; R. Assmann; Helmut Burkhardt; Etienne Carlier; B. Dehning; B. Goddard; Jean Bernard Jeanneret; V. Kain; B. Puccio; J. Wenninger
At the Large Hadron Collider (LHC) with nominal parameters at 7 TeV, each proton beam has an energy of more than 330 MJ threatening to damage accelerator equipment in case of uncontrolled beam loss. To prevent such damage, kickers are fired in case of failure deflecting the beams into dump blocks. The dump blocks are the only elements that can safely absorb the beams without damage. The time constant for particle losses depends on the specific failure and ranges from microseconds to several seconds. Starting with some typical failure scenarios, the strategy for the protection during LHC beam operation is illustrated. The systems designed to ensure safe operation, such as beam dump, beam instruments, collimators / absorbers and interlocks are discussed.
Proceedings of the 2005 Particle Accelerator Conference | 2005
V. Kain; K. Vorderwinkler; J. Ramillon; R. Schmidt; J. Wenninger
The design of LHC protection elements is based on assumptions on damage levels, which are derived from simulations. A dedicated experiment was carried out to cross-check the validity of this approach by trying to damage material in a controlled way with beam. The impact of a 450 GeV beam extracted from the SPS on a specially designed high-Z target with a simple geometry, comprising several typical materials used for LHC equipment, was simulated. The beam intensities for the test were chosen to exceed the damage limits of parts of the target. Results of the simulations are presented and compared with test results.
The 6th workshop on beam instrumentation | 2008
I. Barnett; A. Beuret; B. Dehning; P. Galbraith; K. Henrichsen; M. Jonker; Massimo Placidi; R. Schmidt; L. Vos; J. Wenninger; I. Reichel; F. Tecker
A new method is presented to measure the relative offset of beam position monitors with respect to the magnetic center of quadrupole magnets. Slow unavoidable orbit drifts lead to changing beam positions. The beam position is detected by modulating the strength of the magnetic field of a quadrupole and measuring the amplitude of the induced closed orbit oscillation. The amplitude of the orbit oscillation depends linearly on the modulation strength and on the beam offset in the quadrupole magnet.
Laser and Particle Beams | 2007
N. A. Tahir; R. Schmidt; Markus Brugger; I.V. Lomonosov; A. Shutov; A. R. Piriz; S. Udrea; D. H. H. Hoffmann; C. Deutsch
The Super Proton Synchrotron (SPS) will serve as an injector to the Large Hadron Collider (LHC) at CERN as well as it is used to accelerate and extract proton beams for fixed target experiments. In either case, safety of operation is a very important issue that needs to be carefully addressed. This paper presents detailed numerical simulations of the thermodynamic and hydrodynamic response of solid targets made of copper and tungsten that experience impact of a full SPS beam comprized of 288 bunches of 450 GeV/c protons. These simulations have shown that the material will be seriously damaged if such an accident happens. An interesting outcome of this work is that the SPS can be used to carry out dedicated experiments to study High Energy Density (HED) states in matter.
Proceedings of the 2005 Particle Accelerator Conference | 2005
R. Filippini; B. Dehning; G. Guaglio; F. Rodriguez-Mateos; R. Schmidt; B. Todd; J. Uythoven; A. Vergara-Fernandez; Markus Zerlauth
A large number of complex systems will be involved in ensuring a safe operation of the CERN Large Hadron Collider, such as beam dumping and collimation, beam loss and position monitors, quench protection, powering interlock and beam interlock system. The latter will monitor the status of all other systems and trigger the beam abort if necessary. While the overall system is expected to provide an extremely high level of protection, none of the involved components should unduly impede machine operation by creating physically unfounded dump requests or beam inhibit signals. This paper investigates the resulting trade-off between safety and availability and provides quantitative results for the most critical protection elements.
Physical Review Special Topics-accelerators and Beams | 2015
Bernhard Auchmann; J. Wenninger; Mariusz Sapinski; Eleftherios Skordis; B. Dehning; G. Bellodi; Vera Chetvertkova; Chiara Bracco; Markus Zerlauth; Stefano Redaelli; Anton Lechner; Roderik Bruce; Agnieszka Priebe; Mateusz Jakub Bednarek; R. Schmidt; P.P. Granieri; M. Solfaroli; Arjan Verweij; E. Nebot Del Busto; T Baer; Nikhil Vittal Shetty; Daniel Valuch; D Wollmann; Belen Salvachua; Jens Steckert; Eva Barbara Holzer; Wolfgang Höfle; F. Cerutti
In the years 2009-2013 the Large Hadron Collider (LHC) has been operated with the top beam energies of 3.5 TeV and 4 TeV per proton (from 2012) instead of the nominal 7 TeV. The currents in the superconducting magnets were reduced accordingly. To date only seventeen beam-induced quenches have occurred; eight of them during specially designed quench tests, the others during injection. There has not been a single beam- induced quench during normal collider operation with stored beam. The conditions, however, are expected to become much more challenging after the long LHC shutdown. The magnets will be operating at near nominal currents, and in the presence of high energy and high intensity beams with a stored energy of up to 362 MJ per beam. In this paper we summarize our efforts to understand the quench levels of LHC superconducting magnets. We describe beam-loss events and dedicated experiments with beam, as well as the simulation methods used to reproduce the observable signals. The simulated energy deposition in the coils is compared to the quench levels predicted by electro-thermal models, thus allowing to validate and improve the models which are used to set beam-dump thresholds on beam-loss monitors for Run 2.