| Paper |
Title |
Page |
| WEPP060 |
Abort Gap Cleaning Using the Transverse Feedback System: Simulation and Measurements in the SPS for the LHC Beam Dump System
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2656 |
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- A. Koschik, B. Goddard, W. Höfle, G. Kotzian, D. K. Kramer, T. Kramer
CERN, Geneva
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The critical and delicate process of dumping the beams of the LHC requires very low particle densities within the 3 microseconds of the dump kicker rising edge. High beam population in this so-called 'abort gap' might cause magnet quenches or even damage. Constant refilling due to diffusion processes is expected which will be counter-acted by an active abort gap cleaning system employing the transverse feedback kickers. In order to assess the feasibility and performance of such an abort gap cleaning system, simulations and measurements with beam in the SPS have been performed. Here we report on the results of these studies.
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| TUPC037 |
Development, Production and Testing of 4500 Beam Loss Monitors
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1134 |
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- E. B. Holzer, P. Chiggiato, B. Dehning, G. Ferioli, V. Grishin, J. M. Jimenez, M. Taborelli, I. Wevers
CERN, Geneva
- A. Koshelev, A. Larionov, V. Seleznev, M. Sleptsov, A. Sytin
IHEP Protvino, Protvino, Moscow Region
- D. K. Kramer
TUL, Liberec
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Beam-loss monitoring (BLM) is a key element in the LHC machine protection. 4250 nitrogen filled ionization chambers (IC) and 350 secondary emission monitors (SEM) have been manufactured at the Institute for High Energy Physics (IHEP) in Protvino, Russia, following their development at CERN. Signal speed and robustness against ageing were the main design criteria. Each monitor is permanently sealed inside a stainless-steel cylinder. The quality of the welding was a critical aspect during production. The SEMs are requested to hold a vacuum of 1·10-7 bar. Impurity levels from thermal and radiation-induced desorption should remain in the range of parts per million in the ICs. The difference in sensitivity is about 3·104. To avoid radiation aging (up to 2·108 Gy in 20 years) production of the chambers followed strict UHV requirements. IHEP designed and built the UHV production stand. Due to the required dynamic range of 1·109, the leakage current of the monitors has to stay below 1 pA. Several tests during and after production were performed at IHEP and CERN. A consistently high quality during the whole production period was achieved and the tight production schedule kept at the same time.
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| THPC149 |
Beam Scraping to Detect and Remove Halo in LHC Injection
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3339 |
| |
- P. A. Letnes, S. Bart Pedersen, A. Brielmann, H. Burkhardt, D. K. Kramer
CERN, Geneva
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Fast scrapers are installed in the SPS to detect and remove beam halo before extraction of beams to the LHC, to minimize the probability for quenching of super-conducting magnets in the LHC. We shortly describe the current system and then focus on our recent work, which aims at providing a system which can be used as operational tool for standard LHC injection. A new control application was written and tested with the beam. We describe the current status and results and compare these with detailed simulations.
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| THPC147 |
Generation of 1.5 Million Beam Loss Threshold Values
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3333 |
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- E. B. Holzer, B. Dehning, L. Ponce, M. Sapinski, M. Stockner
CERN, Geneva
- D. K. Kramer
TUL, Liberec
- P. Priebe
Poznan University of Technology, Poznan
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CERN's Large Hadron Collider will store an unprecedented amount of energy in its circulating beams. Beam-loss monitoring (BLM) is, therefore, critical for machine protection. It must protect against the consequences (equipment damage, quenches of superconducting magnets) of excessive beam loss. 4000 monitors will be installed at critical loss locations. Each monitor has 384 beam abort thresholds associated; for 12 integrated loss durations (40 us to 83 s) and 32 energies (450 GeV to 7 TeV). Depending on monitor location, the thresholds vary by orders of magnitude. For simplification, the monitors are grouped in 'families'. Monitors of one family have the same thresholds at start-up; they protect similar magnets against equivalent loss scenarios. The start-up calibration of the BLM system is required to be within a factor of five in accuracy; and the final accuracy should be a factor of two. Simulations (backed-up by control measurements) determine the relation between the BLM signal, the deposited energy and the critical energy deposition for damage or quench (temperature of the coil). The paper presents the details and systematic of determining 1.5 million threshold values.
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