| Paper | Title | Page |
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| WEAZ01 | Overview of beam loss mechanisms in injection and extraction | 172 |
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| WEAZ02 | Beam Loss at the Fermilab Booster and Main Injector: Recent Experience and the Road to MW Class Beams | 0 |
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| The Fermilab Booster and Main Injector synchrotrons produce high-rate proton beams for neutrino and antiproton production. Operation of these machines at high beam power has required novel approaches to managing beam loss during acceleration and at extraction. Routinely, the beam loss in the Booster limits it throughput, instead of any physical limitation. With pending intensity upgrades the same may also become true of the Main Injector. Future advances in beam power require a fully complementary reduction of oncontrolled losses. | ||
| WEAZ03 | DESIGN AND TESTS OF A LOW-LOSS MULTI-TURN EJECTION FOR THE CERN PS | 192 |
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| Following the positive results of the three-year measurement campaign at the CERN Proton Synchrotron, the study of a possible implementation of the proposed multi-turn extraction based on beam splitting with stable islands in the transverse phase space was undertaken. A substantial reduction of beam losses, with respect to the present extraction scheme, should be achieved with the proposed technique when delivering the high-intensity proton beams required for the planned CERN Neutrino to Gran Sasso Project. Major modifications to the ring layout are foreseen, such as a new design of the extraction bumps including also the installation of three additional kickers to create a closed-bump over the five turns used to extract the split beam. The ring aperture was reviewed and improvements are proposed to reduce possible beam losses between beam splitting and extraction. The goal consists of implementing the proposed changes by beginning of 2008 and to commission the novel extraction during the 2008 PS physics run. | ||
| WEAZ04 | Beam-Induced Damage to the Tevatron Components and What Has Been Done About It | 205 |
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| The Tevatron collimators and magnets were damaged and two thirds of the superconducting ring were quenched on December 5, 2003, induced by a failure in the CDF Roman Pot detector positioning at the end of a 2-TeV proton-antiproton colliding beam store. Analysis of a failure in the abort kicker AC distribution, and detailed modeling of a misbehaved beam dynamics, induced energy deposition and ablation process in the collimator material, have provided a good understanding of the event. The improvements to the detectors, Tevatron quench protection and beam loss monitor systems to avoid such an accident in the future are described. | ||
| WEAZ05 | Very Fast Beam Losses at HERA, and what has been done about it | 215 |
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| During the Luminosity upgrade of HERA in 2000/2001 more than 50 new magnets were installed close to the interaction region to provide a stronger focussing of the two beams. Some of these magnets are located at very large values of the betatron function and therefore act with a large gain on the beam. Sudden changes in the power supply currents had led to very fast beam losses, creating quenches and increased radiation levels. This talk will discuss the improvements made to the HERA machine protection system to make sure that the beam is dumped in time in case of these events. | ||
| WEAZ06 | Transfer line damage during high intensity proton beam extraction from the SPS in 2004 | 228 |
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| During extraction of a high intensity beam from the SPS in 2004 an incident occurred in which the vacuum chamber of a transfer line quadrupole magnet was badly damaged. The beam was a 450 GeV full LHC injection batch of 3.4·1013 p+ in 288 bunches, and was extracted with the wrong trajectory. The incident causes have been identified, with details reconstructed from the logged data and the damage to the vacuum chamber. The remedial measures which were taken are explained, and further recommendations made concerning the interlocking system performance and tests, as well as the operational procedures which must be adopted when commissioning with high intensities. The specific issues of how the incident happened, why the existing protection system was not sufficient and what can/has been done about it are addressed. | ||
| WEAZ07 | Shock wave propagation near 7 TeV proton beam in LHC collimator materials | 241 |
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A study is presented to estimate the influence of the impact of a 7 TeV proton beam on the physical-mechanical material properties, such as C for collimators, and Cu elsewhere. The high energy stored in each bunch can produce a shock wave near the impacting proton beam in these materials. The theoretical model for the investigations of shock wave propagation in the collimator materials takes into account ionization, electronic excitation, and energy transfer from excited electronic subsystem in the materials to the ionic subsystem. The change of other physical properties of the material is also considered. The deposited energy is calculated with FLUKA [1]. The numerical results of the microstructure change in the material are presented for different numbers of bunches. The method allows investigating changes of density and internal pressure, the distributions of atomic and sound velocities, and the temperature profiles in electronic and ionic subsystems of materials near the front of shock wave. These results are very relevant for the understanding the behavior of collimator materials used in LHC under 7 TeV proton beam.
[1] A. Fasso et al. The physics models of FLUKA: status and recent development, CHEP 2003, LA Jolla, California, 2003 |