| Paper |
Title |
Page |
| MOPC095 |
Mechanical and Thermal Prototype Testing for a Rotatable Collimator for the LHC Phase II Collimation Upgrade
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286 |
| |
- J. C. Smith, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz
SLAC, Menlo Park, California
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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.
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| MOPC096 |
Design of a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade
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289 |
| |
- J. C. Smith, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz
SLAC, Menlo Park, California
- L. Lari
EPFL, Lausanne
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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: - Collimator jaw deflection due to heating and sagita must be small when operated in the steady state condition,
- Collimator jaws must withstand transitory periods of high beam impaction with no permanent damage,
- Jaws must recover from accident scenario where up to 8 full intensity beam pulses impact on the jaw surface and
- The beam impedance contribution due to the collimators must be small to minimize coherent beam instabilities.
The current design will be presented.
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| MOPP031 |
Challenges and Concepts for Design of an Interaction Region with Push-pull Arrangement of Detectors - an Interface Document
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616 |
| |
- A. Seryi, T. W. Markiewicz, M. Oriunno, M. K. Sullivan
SLAC, Menlo Park, California
- D. Angal-Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
- B. Ashmanskas, V. R. Kuchler, N. V. Mokhov
Fermilab, Batavia, Illinois
- K. Buesser
DESY, Hamburg
- P. Burrows
OXFORDphysics, Oxford, Oxon
- A. Enomoto, Y. Sugimoto, T. Tauchi, K. Tsuchiya
KEK, Ibaraki
- A. Herve, J. A. Osborne
CERN, Geneva
- A. A. Mikhailichenko
Cornell University, Department of Physics, Ithaca, New York
- B. Parker
BNL, Upton, Long Island, New York
- T. Sanuki
Tohoku University, School of Scinece, Sendai
- J. Weisend
NSF, Arlington
- H. Y. Yamamoto
Tohoku University, Sendai
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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.
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| MOPP064 |
Secondary Electron Yield Measurements and Groove Chambers Update Tests in the PEP-II Beam Line
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691 |
| |
- M. T.F. Pivi, F. King, R. E. Kirby, T. W. Markiewicz, T. O. Raubenheimer, J. Seeman, L. Wang
SLAC, Menlo Park, California
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In the Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in straight sections to test this possible mitigation technique for the electron cloud effect in the positron damping ring (DR) of the future Linear Colliders such as ILC and CLIC. We have also installed chambers to monitor the secondary electron yield (SEY) of TiN, TiZrV (NEG) and technical accelerator materials under the effect of electron and photon conditioning in situ. Furthermore, we have also installed test chambers in a new 4-magnet chicane. We describe the ongoing R&D effort to mitigate the electron cloud effect in the ILC damping ring, the chambers installation in the PEP-II and latest results.
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| TUPP073 |
Bench-top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade
|
1703 |
| |
- J. C. Smith, K. L.F. Bane, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California
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| |
The Phase II upgrade to the LHC collimation system 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. Simulations have been performed in MAFIA to study both the resistive wall and geometric impedance contributions of our rotatable collimator design. Benchtop stretched coil probe impedance measurements have also been performed on prototype components to directly measure the low frequency impedance contributions. The design also calls for an RF contact interface at the jaw end. This contact resistance must be a small fraction of a milliohm in order to limit transverse impedance. DC resistance measurements in a custom built test chamber have been performed to test the performance of various metal pairs and surface coatings.
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| WEPP071 |
Preliminary Exploratory Study of Different Phase II Collimators
|
2683 |
| |
- L. Lari, R. W. Assmann, A. Bertarelli, C. Bracco, M. Brugger, F. Cerutti, A. Dallocchio, A. Ferrari, M. Mauri, S. Roesler, L. Sarchiapone, V. Vlachoudis
CERN, Geneva
- J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith
SLAC, Menlo Park, California
- L. Lari
EPFL, Lausanne
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The LHC collimation system is installed and commissioned in different phases, following the natural evolution of the LHC performance. To improve cleaning efficiency towards the end of the low beta squeeze at 7TeV, and in stable physics conditions, it is foreseen to complement the 30 highly robust Phase I secondary collimators with low impedance Phase II collimators. At this stage, their design is not yet finalized. Possible options include metallic collimators, graphite jaws with a movable metallic foil, or collimators with metallic rotating jaws. As part of the evaluation of the different designs, the FLUKA Monte Carlo code is extensively used for calculating energy deposition and studying material damage and activation. This report outlines the simulation approach and defines the critical quantities involved.
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| WEPP072 |
Evaluation of Beam Losses and Energy Deposition for A Possible Phase II Design for LHC Collimation
|
2686 |
| |
- L. Lari, R. W. Assmann, C. Bracco, M. Brugger, F. Cerutti, A. Ferrari, M. Mauri, S. Redaelli, L. Sarchiapone, V. Vlachoudis, Th. Weiler
CERN, Geneva
- J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith
SLAC, Menlo Park, California
- L. Lari
EPFL, Lausanne
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The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.
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