| Paper | Title | Page |
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| TUPS036 | High Energy Beam Impacts on Beam Intercepting Devices: Advanced Numerical Methods and Experimental Set-up | 1614 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behavior of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC Tungsten Collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedicated experimental program is proposed, relying on the HiRadMat test facility at CERN. Experimental aspects such as sample-holder design and test set-up are described. |
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| TUPZ012 | Machine-induced Showers entering the ATLAS and CMS Detectors in the LHC | 1825 |
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| One source of experimental background in the LHC is showers induced by particles hitting the upstream collimators or particles that have been scattered on the residual gas. We estimate the flux and distribution of particles entering the ATLAS and CMS detectors through FLUKA simulations originating from tertiary collimator hits and inelastic beam-gas interactions. Comparisons to MARS results are also presented. | ||
| WEPC175 | FLUKA Studies of the Asynchronous Beam Dump Effects on LHC Point 6 | 2397 |
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| The LHC is a record-breaking machine for beam energy and intensity. An intense effort has therefore been deployed in simulating critical operational scenarios of energy deposition. FLUKA is the most widely used code for this kind of simulations at CERN because of the high reliability of its results and the ease to custom detailed simulations all along hundreds of meters of beam line. We have investigated the effects of an asynchronous beam dump on the LHC Point 6 where, beams with a stored energy of 360 MJ, can instantaneously release up to a few J cm-3 in the cryogenic magnets which have a quench limit of the order of the mJ cm-3. In the present paper we will briefly introduce FLUKA, describe the simulation approach, and discuss the evaluated maximum energy release onto the superconducting magnets during an asynchronous beam dump. We will then analyse the shielding provided by collimators installed in the area and discuss safety limits for the operation of the LHC. | ||
| THPS055 | Controlling Beamloss at Injection into the LHC | 3553 |
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| Losses at injection into the superconducting LHC can adversely affect the machine performance in several important ways. The high injected beam intensity and energy mean that precautions must be taken against damage and quenches, including collimators placed close to the beam in the injection regions. Clean injection is essential, to avoid spurious signals on the sensitive beam loss monitoring system which will trigger beam dumps. In addition, the use of the two injection insertions to house downstream high energy physics experiments brings constraints on permitted beam loss levels. In this paper the sources of injection beam loss are discussed together with the contributing factors and various issues experienced in the first full year of LHC operation. Simulations are compared with measurement, and the implemented and planned mitigation measures and diagnostic improvements are described. An outlook for future LHC operation is given. | ||
| THPZ032 | Evaluation of the Combined Betatron and Momentum Cleaning in Point 3 in Terms of Cleaning Efficiency and Energy Deposition for the LHC Collimation Upgrade | 3762 |
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Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. The Phase I LHC Collimation System Upgrade could include moving part of the Betatron Cleaning from LHC Point 7 to Point 3 to improve both operation flexibility and intensity reach. In addition, the partial relocation of beam losses from the current Betatron cleaning region at Point 7 will mitigate the risks of Single Event Upsets to equipment installed in adjacent and partly not adequate shielded areas. A combined Betatron and Momentum Cleaning scenario at Point 3 implies the installation of new collimators and a new collimator aperture layout. This paper shows the whole LHC Collimator Efficiency variation with the new layout proposed at different beam energies. As part of the evaluation, energy deposition distribution in the IR3 region gives indications about the effect of this new implementation not only on the collimators themselves but also on the other beam line elements. |
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