| Paper | Title | Page |
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| MOPC085 | High Power Neutron Converter for Low Energy Proton/Deuteron Beams: Liquid Metal Driving System | 256 |
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| Nowadays in BINP, Russia, the high-power high-temperature rotated graphite-made neutron converter is proposed in order to use neutron source for SPES (INFN-LNL, Italy) and SPIRAL-II (GANIL, France). The target is designed to produce up to 1014 neutron per second within the energy range of several MeV under irradiation by proton/deuteron beam of power up to 200 kW. One of main problem on the converter development is to provide the reliable and effective driving gear and cooling systems. The main elements of the system must be liquid metal pumps and motors, cooling channels and heat exchanger. This paper describes proposed scheme, its basic technical parameters, estimations of the system whole as well as of separate elements. The lead-tin alloy is used as the transmission agent. At present the prototype of liquid metal motor/pump is successfully manufactured and operates for more than 16000 h in continuous regime. | ||
| MOPC086 | IFMIF-EVEDA Accelerator: Beam Dump Design | 259 |
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| The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA cw deuteron accelerator prototype for verifying the validity of the accelerator design for IFMIF. A beam stop will be used for the RFQ and DTL commissioning as well as for the EVEDA accelerator tests. Therefore, this component must be designed to stop 5 MeV and 9 MeV deuteron beams with a maximum power of 1.12 MW. The first step of the design is the beam-facing material selection. The criteria used for this selection are low neutron production, low activation and good thermomechanical behavior. A thermomechanical analysis with ANSYS has been performed for a few materials which show good behavior from the radiological point of view. The input data are the expected beam shape and divergence at the beam dump entrance produced by the high energy beam line quadrupoles, a conical beam stop shape and the preliminary design of the cooling system. As a conclusion of the previous studies a conceptual design of the beam stop will be presented. | ||
| MOPC087 | The MERIT (nTOF-11) High Intensity Liquid Mercury Target Experiment at the CERN PS | 262 |
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The MERIT (nTOF-11) experiment is a proof-of-principle test of a target system for high power proton beams to be used as a front-end for a neutrino factory complex or a muon collider. The experiment took data in autumn 2007 using the fast extracted beam from the CERN Proton Synchrotron (PS) with a maximum intensity of about 30TP per pulse. The target system, based on a free mercury jet, is capable of intercepting a 4-MW proton beam inside a 15-T magnetic field Such a field is required to capture the low-energy secondary pions which will provide the source of the required intense muon beams. Particle detectors have been installed around the target setup in order to measure the secondary particle flux out of the target and probe cavitation effects in the mercury jet when hit with variable intensity beams. The data analysis is ongoing: the results presented at this conference will demonstrate the validity of the liquid mercury target concept.
For the MERIT collaboration. |
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| MOPC088 | High Power Neutron Converter for Low Energy Proton/Deuteron Beams: Test Facility | 265 |
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| This paper presents conceptual design of test facility, that is now under creation in the framework of development of high power neutron targets for SPES (INFN-LNL, Italy) and SPIRAL-II (GANIL, France). General destination of facility is to test different target systems and elements (hot converter unit, liquid metal driving gear and cooling systems) as well as experimental checking of supply, protection and control methods etc. Also, this facility must be used as a base for input quality control of targets as a whole in future. The structure, general features and experimental possibilities of facility are described. | ||
| MOPC089 | About Carbides-made Nanoceramics Fission Target for RIB Production | 268 |
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| Intensities of RIBs can be increased with improvement of release efficiency of fission targets. One of factor, which limits release efficiency of targets, is efficiency of release of isotopes from target material. This paper presents investigation of dependence of release efficiency from ceramics target on its grain size and inter-grains pores, as well shows some efficiency limits and ways to improve it. Simulations were performed for uniform target material made from powder of uranium carbide. Inter-grain spaces are taken relative to grain sizes, as another parameter to optimize is high density of target material. Results show that optimal grain size is in the range of hundreds - thousands nanometers, while recent target materials utilize one order more sizes of grains. In addition, key points of production of such ceramics are discussed. The beam technologies allow producing the nanopowders from carbides of different metals with controlled grain size. Exact methods also give to us possibilities to obtain ceramics with optimal ratio between grain and pores sizes. Possible problems and preliminary program of experiments and tests are discussed. | ||
| MOPC090 | Driver Beam-led EURISOL Target Design Constraints | 271 |
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The EURISOL (European Isotope Separation Online) Design Study is addressing new high power target design challenges. A three-step method* was proposed to split the high power linac proton driver beam into one H- branch for the 4 MW mercury target that produces radioactive ion beams (RIB) via spallation neutron-induced fission in a secondary actinide target and three 100 kW H+ branches for the direct targets producing RIBs via fragmentation and spallation reactions. This scheme minimises transient thermo-mechanical stresses on targets and preserves the cw nature of the driver beam in the four branches. The heat load for oxides, carbides, refractory metal foils and liquid metals is driven by the incident proton driver beam while for actinides, exothermic fission reactions are an additional contribution. This paper discusses the constraints that are specific to each class of material and the target design strategies. An emphasis is placed on the modern engineering numerical tools and experimental methods used to validate the target designs.
*A. Facco, R. Paparella, D. Berkovits, Isao Yamane, "Splitting of high power, cw proton beams", Physical Review Special Topics - Accelerators and Beams (2007). |
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| MOPC091 | Benchmarking of Collimation Tracking Using RHIC Beam Loss Data | 274 |
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| State-of-the-art tracking tools were recently developed at CERN to study the cleaning efficiency of the Large Hadron Collider (LHC) collimation system. These tools can be benchmarked using data taken from operations of the Relativistic Heavy Ion Collider (RHIC) multi-stage collimation system. This article reviews preliminary simulation results on both the location and the intensity of proton losses around the RHIC lattice. Comparison with live measurements from the beam loss monitors are also shown in order to assess the accuracy of the predictions in the LHC case. | ||
| MOPC092 | Single Particle Multi-turn Dynamics During Crystal Collimation | 277 |
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| As the increase in luminosity remains a high-profile issue for current and future accelerator projects, protecting superconducting magnets from beam induced quenches implies using state-of-the-art halo cleaning devices given the required beam intensities. In CERN's LHC case, a multi-stage collimation system is being set up so as to provide a halo cleaning efficiency up to 99.995%. In order to improve this system even further, US-LARP funded studies have started to appreciate the use of a silicon-based crystal as a primary target for the halo particles. Dedicated experiments have recently been performed in an SPS extraction line for a bent silicon crystal in case of single-pass particles. This article compares the published results of this experiment with simulations using established tracking codes. The goal is to better describe the main physics mechanisms involved in the beam-crystal interaction. A simple algorithm is then introduced to allow for fast tracking of the effect of a crystal on a high energy proton beam over many turns. The general feasibility of single particle, multi-turn crystal experiments at the SPS (CERN) and Tevatron (Fermilab) and their outline are discussed. | ||
| MOPC093 | Experimental Study of Radiation Damage in Carbon Composites and Graphite Considered as Targets in the Neutrino Super Beam | 280 |
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Carbon composites have been of primary interest as materials of choice for a multi-MW neutrino superbeam which desires low-Z pion production target. Beam on target experiments conducted at BNL made the case stronger in their favor, as compared to graphite, by demonstrating their excellent shock resistance which is directly linked with their extremely low thermal expansion. Since target survivability also depends on resistance to prolonged radiation, a series of irradiation damage studies on carbon composites and graphite were launched. While carbon composites at moderate doses exhibited interesting behavior of damage reversal through thermal annealing, at higher dose levels of peak proton fluences >5x1020 protons/cm2 they exhibited serious structural degradation. The experimental study also showed that graphite suffered similar damage when subjected to same fluence level. The paper discusses the findings of the experimental studies focusing on these materials and attempts to explain their structural degradation observed under high proton fluences given the excellent survivability record, especially of graphite, under high neutron fluences in nuclear reactor settings.
Work performed under the auspices of the US DOE. |
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| MOPC094 | Irradiation Effects on the Physio-mechanical Properties of Super-alloys Characterized by Low Thermal Expansion | 283 |
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In an effort to address the limitations on high power accelerator target performance prompted by the elevated dose levels and the associated irradiation damage, an experimental study has been undertaken to evaluate the potential applicability of super alloys characterized by low thermal expansion over certain thermal regimes. The intriguing properties associated with materials such as super-Invar and the “gum” metal (Ti-12Ta-9Nb-3V-6Zr-O) are observed in their un-irradiated state. Irradiations were performed using the 200 MeV protons of the BNL Linac and/or a neutron flux generated by the stopping of the primary 112 MeV protons upstream of the exposed super-alloys. The paper presents the post-irradiation analysis results which reveal interesting damage reversal by the super-invar and unexpected low threshold of radiation resistance by the “gum” metal.
Work performed under the auspices of the US DOE. |
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| MOPC095 | Mechanical and Thermal Prototype Testing for a Rotatable Collimator for the LHC Phase II Collimation Upgrade | 286 |
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| The Phase II upgrade to the LHC collimation systems calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. A series of prototype collimator jaws have been tested for both mechanical and thermal compliance with the design goals. Collimator jaw shape after thermal expansion benchtop tests were compared to ANSYS simulation results. Mechanical tests were also performed to demonstrate fabrication precision and collimator movement operation as designed. | ||
| MOPC096 | Design of a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade | 289 |
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The Phase II upgrade to the LHC collimation systems calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. Design issues include:
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| MOPC098 | LHC Particle Collimation by Hollow Electron Beams | 292 |
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| Electron Lenses built and installed in Tevatron have proven themselves as safe and very reliable instruments which can be effectively used in hadron collider operation for a number of applications, including compensation of beam- beam effects, DC beam removal from abort gaps, as a diagnostic tool. In this presentation we consider a possibility of using electron lenses with hollow electron beam for ion and proton collimation in LHC. | ||
| MOPC099 | Ion Catcher System for the Stabilisation of the Dynamic Pressure in SIS18 | 295 |
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| In synchrotrons operated with intermediate charge state heavy ion beams, intensity dependent beam losses have been observed. The origin of these losses is the change of charge state of the beam ions at collisions with residual gas atoms. The resulting m/q deviation from the reference beam ion leads to modified trajectories in dispersive elements, which finally results in beam loss. At the impact on the beam pipe, gas molecules are released by ion stimulated desorption which increase the vacuum pressure locally. In turn, this pressure rise will enhance the charge change- and particle loss process and finally cause significant beam loss within a very short time. In order to suppress and control the gas desorption process, a dedicated ion catcher system incorporating NEG coated surfaces and low-desorption rate materials has been developed and two prototypes were installed in SIS18. The design of the scraper and measured effect on the dynamic residual gas pressure are presented. |