Paper | Title | Page |
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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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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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MOPP036 | Dark Current Model for ILC Main Linac | 625 |
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In the ILC Main Linac the dark current electrons, generated in SRF cavity can be accelerated to hundreds of MeV before being kicked out by quadrupoles and thus will originate electromagnetic cascade showers in the surrounding materials. Some of the shower secondaries can return back into vacuum and re-accelerated again. The results of simulation of the dark current dynamics and energy deposition along the linac are discussed in paper. | ||
WEPC053 | An Experimental Study of Radiation-induced Demagnetization of Insertion Device Permanent Magnets | 2112 |
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High brilliance in the 3GeV new light source NSLS II is obtained from the high magnetic fields in insertion devices (ID). The beam lifetime is limited to 3h by single Coulomb scattering in the Bunch (Touschek effect). This effect occurs everywhere around the circumference and there is unavoidable beam loss in the adjacent low-aperture insertion devices. This raises the issue of degradation and damage of the permanent magnetic material by irradiation with high energy electrons and corresponding shower particles. It is expected that IDs, especially those in-vacuum, would experience changes resulting from exposure to gamma rays, x-rays, electrons and neutrons. By expanding an on-going material radiation damage study at BNL the demagnetization effect of irradiation consisting primarily of neutrons, gamma rays and electrons on a set of NdFeB magnets is studied. Integrated doses of several Mrad to a few Grad were achieved at the BNL Isotope Facility with a 112-MeV, 90-uA proton beam. Detailed information on dose distributions and particle energy spectra on the NdFeB magnets was obtained with the MARS15 Monte-Carlo code. This paper summarizes the results of this study.
Work performed under the auspices of the US DOE. |
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WEPD036 | Radiation and Thermal Analysis of Superconducting Quadrupoles in the Interaction Region of Linear Collider | 2488 |
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The upcoming and disrupted electron and positron beams in the baseline design of ILC interaction region are focused by compact FD doublets each consisting of two small-aperture superconducting quadrupoles and multipole correctors. These magnets will work in a severe radiation environment generated primarily by incoherent pairs and radiative Bhabhas. This paper analyzes the radial, azimuthal and longitudinal distributions of radiation heat deposition in incoming and disrupted beam doublets. Operation margins of baseline quadrupoles based on NbTi superconductor and direct wind technology as well as alternative designs based on NbTi or Nb3Sn Rutherford cables are calculated and compared. The possibilities of reducing the heat deposition in magnet coils using internal absorbers are discussed. | ||
WEPD037 | Nb3Sn Quadrupoles in the LHC IR Phase I Upgrade | 2491 |
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After some years of operation at nominal parameters, the LHC will be upgraded for higher luminosity. At the present time it is planned to perform the IR upgrade in two phases with the target luminosity for Phase I of ~2.5· 1034 cm-2s-1 and up to 1035 cm-2s-1 for Phase II. In Phase I the baseline 70-mm NbTi low-beta quadrupoles will nominally be replaced with larger aperture NbTi magnets and in Phase II with higher performance Nb3Sn magnets. U. S.-LARP is working on the development of large aperture high-performance Nb3Sn magnet technologies for the LHC Phase II luminosity upgrade. Recent progress also suggests the possibility of using Nb3Sn quadrupoles in the Phase I upgrade, improving the luminosity through an early demonstration of Nb3Sn magnet technology in a real accelerator environment. This paper discusses the possible hybrid optics layouts for Phase I upgrades with both NbTi and Nb3Sn quadrupoles, introducing magnet parameters and issues related to using Nb3Sn quadrupoles including magnet length and aperture limitations, field quality, operation margin, etc. Possible transition scenarios to Phase II are also discussed. | ||
WEPP031 | Energy Deposited in the High Luminosity Inner Triplets of the LHC by Collision Debris | 2587 |
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The 14 TeV center of mass proton-proton collisions in the LHC produce not only interesting events for physics but also debris ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of the deposited heat, that has to be transferred to the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC baseline are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the comparison and consolidation of the calculations, a dedicated study of a simplified model has been made, showing satisfactory agreement. | ||
WEPP047 | Optics Implications of Implementing Nb3Sn Magnets in the LHC Phase I Upgrade | 2626 |
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CERN has encouraged the US-LARP collaboration to participate in Phase I of the LHC luminosity upgrade by analyzing the benefits gained by using Nb3Sn technology to replace the functionality of select magnets CERN is commited to construct using NbTi magnets. Early studies have shown that the much higher gradients (shorter magnetic lengths) and energy load of Nb3Sn magnets compared to their NbTi counterpars is very favorable allowing the insertion of additional absorbers between Q1 & Q2, for example. This paper discusses the relative merits of the NbTi and Nb3Sn options. | ||
MOPP031 | Challenges and Concepts for Design of an Interaction Region with Push-pull Arrangement of Detectors - an Interface Document | 616 |
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Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics system, for alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent. | ||
WEPP169 | The MERIT High-power Target Experiment at the CERN PS | 2886 |
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The MERIT experiment was designed as a proof-of-principle test of a target system based on a free mercury jet inside a 15-T solenoid that is capable of sustaining proton beam powers of up to 4MW. The experiment was run at CERN in the fall of 2007. We describe the results of the tests and their implications. |