| Paper | Title | Page |
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| TUPFI022 | Power Load from Collision Debris on the LHC Point 8 Insertion Magnets Implied by the LHCb Luminosity Increase | 1382 |
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| LHCb is aiming to upgrade its goal peak luminosity up to a value of 2 1033 cm-2 s−1 after LS2. We investigate the collision debris impact on the machine elements by extensive FLUKA simulations, showing that the present machine layout is substantially compatible with such a luminosity goal. In particular the installation of a TAS (Target Absorber ofSecondaries, installed in front of the final focus Q1-Q3 quadrupole triplet in the LHC high luminosity insertions) turns out not to be necessary on the basis of the expected peak power deposition in the Q1 superconducting coils. A warm protection may be desirable to further reduce heat load and dose on the D2 recombination dipole, due to the absence of the TAN (Target Absorber of Neutrals, present in Point 1 and 5). | ||
| TUPFI027 | Energy Deposition Studies for Fast Losses during LHC Injection Failures | 1397 |
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| Several instances of injection kicker magnet (MKI) failures have occurred in the first years of LHC operation, leading to misinjections or to accidental kicks of circulating bunches. In a few cases, MKI modules imparted a partial or an increased beam deflection, resulting in grazing bunch impact on beam-intercepting devices and consequently leading to significant secondary showers to downstream accelerator elements. In this study, we investigate different failure occurrences where miskicked bunches were incident on the injection beam stopper (TDI) and on one of the auxiliary injection collimators (TCLIB), respectively. FLUKA shower calculations were performed to quantify the energy deposition in superconducting magnets. Different sections of the LHC insertion regions 2 and 8 were studied, including the separation dipole and the inner triplet downstream of the TDI as well as matching section and dispersion suppressor adjacent to the TCLIB. The obtained results are evaluated in view of quench and damage limits. | ||
| THPEA045 | Beam Induced Quenches of LHC Magnets | 3243 |
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| In the years 2009-2013 LHC was operating with the beam energy of 3.5 and 4 TeV instead of the nominal 7 TeV, with the corresponding currents in the superconducting magnets also half nominal. To date only a small number of beam-induced quenches have occurred, with most being due to specially designed quench tests. During normal collider operation with stored beam there has not been a single beam induced quench. This excellent result is mainly explained by the fact that the cleaning of the beam halo worked very well and, in case of beam losses, the beam was dumped before any significant energy was deposited in the magnets. However, conditions are expected to become much tougher after the long LHC shutdown, when the magnets will be working at near nominal currents in the presence of high energy and intensity beams. This paper summarizes the experience to date with beam-induced quenches. It describes the techniques used to generate controlled quench conditions which were used to study the limitations. Results are discussed along with their implication for LHC operation after the first Long Shutdown. | ||
| THPEA047 | Diamond Particle Detector Properties during High Fluence Material Damage Tests and their Future Applications for Machine Protection in the LHC | 3249 |
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| Experience with LHC machine protection (MP) during the last three years of operation shows that the MP systems sufficiently protect the LHC against damage in case of failures leading to beam losses with a time constant exceeding 1ms. An unexpected fast beam loss mechanism, called UFOs, was observed, which could potentially quench superconducting magnets. For such fast losses, but also for better understanding of slower losses, an improved understanding of the loss distribution within a bunch train is required. Diamond particle detectors with bunch-by-bunch resolution and high dynamic range have been developed and successfully tested in the LHC and in experiments to quantify the damage limits of LHC components. This paper will focus on experience gained in use of diamond detectors. The properties of these detectors were measured during high-fluence material damage tests in CERN's HiRadMat facility. The results will be discussed and compared to the cross-calibration with FLUKA simulations. Future applications of these detectors in the LHC to understand beam losses and to improve the protection against fast particle losses will be discussed. | ||
| THPFI059 | Robustness Test of a Silicon Strip Crystal for Crystal-assisted Collimation Studies in the LHC | 3427 |
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Over the past years, the UA9 experiment has successfully demonstrated the viability of enhancing the collimation efficiency of proton and ion beams in the SPS by means of bent crystals. An extension of UA9 to the LHC has been recently approved. The conditions imposed by the LHC operational environment, in particular the tremendous energy density of the beam, require a reliable understanding of the crystal integrity in view of potential accident scenarios such as an asynchronous beam dump. For this purpose, irradiation tests have been performed at the CERN-HiRadMat facility to examine the mechanical strength of a silicon strip crystal in case of direct beam impact. The tests were carried out using a 440 GeV proton beam of 0.5 mm transverse size. The crystal, 3 mm long in beam direction, was exposed to a total of 2*1014 protons, with individual pulse intensities reaching up to 3*1013. First visual inspections reveal no macroscopic damage to the crystal. Complementary post-irradiation tests are foreseen to assess microscopic lattice damage as well as the degradation of the channelling efficiency.
On behalf of the UA9 Collaboration. |
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