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| TUAZ01 | Overview of recent halo diagnosis and non-destructive beam profile monitoring | electron, synchrotron, laser, diagnostics | 54 | ||
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Beam profile (emittance) and beam halo are characteristic properties of high-intensity and high energy beams that might limit the performance of the adjacent accelerator. Therefore a reliable measurement and determination of these parameters is most helpful for understanding, tuning and improvement of the whole accelerator chain to achieve the best (at least the design-) performance. This talk will give an overview over recent instruments used for non-destructive beam profile and halo monitoring and will discuss their limits, experiences and latest improvements.
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| TUAZ02 | High-Intensity Beam Collimation and Targetry | collimation, target, beam-losses, proton | 74 | ||
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Principles, design criteria and realization are described for reliable collimation systems for the high-power accelerators (Fermilab Booster and Main Injector, SNS, J-PARC), hadron colliders (Tevatron and LHC) and e+e- linear colliders (ILC). Factors affecting the expected and achieved collimation performances are analyzed. Functionality of collimators as the key elements of the machine protection system are considered using as an example a recent beam accident case in the Tevatron. A substantial progress on the crystal collimation front is described. The key issues are considered in design of high-power target systems and achieving their best performance. Simulation code requirements and recent benchmarking results are presented. A status of conventional neutrino targets and neutrino factory target concepts is described along with performed and planned beam tests. Overview of the target and collimator material beam tests concludes this report.
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| TUAZ05 | Comparison of Graphite and Diamond Structured Carbon Stripper Foils under Operational Conditions at the Los Alamos PSR | proton, injection, beam-losses, electron | 112 | ||
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In the Los Alamos Proton Storage Ring H–Ions merge with circulating protons in a bending magnet and are stripped of their two electrons in a carbon stripper foil. The circulating protons continue to interact with the foil. Despite efforts to minimize the number of these foil hits, like “painting” of the vertical phase space, they can not totally be eliminated. As a result foil heating and radiation damage limit the lifetime of these foils. In recent years LANL has collaborated with KEK to improve the graphite foils in use at PSR and these foils now last typically for two months. Recently an alternative in the form of diamond structured carbon foils has been proposed for use at SNS. Depending on the grain size these are referred to as microcrystalline or nanocrystalline foils. Both types have been tested in PSR, with quite different results. While the microcrystalline foil failed catastrophically before production beam currents were reached the nanocrystalline foil was successfully used in normal operation for several weeks. Advantages of the diamond foil concept as well as some noteworthy differences that we observed with respect to the LANL graphite foils will be discussed here.
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| TUBZ04 | Experimental Studies of Targets and Collimators for High Intensity Beams | target, proton, controls, isotope-production | 143 | ||
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Intense muon or neutrino beams require high-performance targets intercepting multi MW proton beams. To achieve it one must push the envelope of the current knowledge regarding material behavior and endurance for both short and long exposure. It is also true for collimator structures intercepting the halo of the intense beam under normal or the entire beam during off-normal conditions. The limitations of most materials in playing such pivotal roles have led to an extensive search and experimentation with new alloys and composites that, at first glance, appear to possess the right combination of properties satisfying target and /or collimation requirements. In this study, a number of new and “smart” materials are experimentally evaluated for resilience to radiation damage and potential use in target and collimation schemes. These include targets for the muon collider and the neutrino superbeam as well as LHC collimation. Results of the on-going experimental effort under way at BNL and involving heavy irradiation of candidate materials using 200 MeV proton beams and post-irradiation analysis for irradiation damage assessment will be presented.
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| WEAZ07 | Shock wave propagation near 7 TeV proton beam in LHC collimator materials | proton, target, coupling, electron | 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.
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[1] A. Fasso et al. The physics models of FLUKA: status and recent development, CHEP 2003, LA Jolla, California, 2003 |
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| THAZ01 | Experience with high-power operation of the PSI proton accelerator facility | target, cyclotron, proton, diagnostics | 274 | ||
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The PSI proton accelerator delivers a maximun current of 2 mA (routinely 1.9 mA) at 590 MeV. Ongoing developments aim at an upgrade of the beam current to 3 mA. This will result in an increase of the beam power from 1.2 to 1.8 MW on the pion/muon production targets and from 0.8 to 1.2 MW on the neutron spallation source SINQ. Our approach to the safe operation of a facility a these power levels will be presented. This includes considerations on the design of the cyclotrons, the beam lines and the tools to handle highly radioactive components. The protection of the facility via device controls, beam diagnostics and loss monitoring will be discussed. The specific requirements for operation with a sensitive liquid metal target like MEGAPIE will also be addressed.
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