linear-collider

Paper	Title	Other Keywords	Page
MOXACH01	Worldwide Perspectives in Accelerators and the Rôle of CERN	collider, proton, luminosity, factory	1
	R. Aymar CERN, Geneva
	After an analysis of the most probable medium and long-term evolution of Particle Accelerators and their worldwide perspectives, the presentation focuses on the specific role of CERN. It emphasizes CERNs mandate as defined by its convention, which is not only to build and operate the laboratory as a centre of excellence but to organize and steer particle physics in Europe. It should be the place where a coherent strategy for the whole field of European Particle Physics is discussed and elaborated in the best interest of the whole community. CERN should act as the driving force in the centre of a network of multilateral collaborating institutes where each laboratory brings its own contribution towards a common goal in a coordinated way following its specific skills and resources. It should favour mutual exchanges and collaborations to enable developments covering the whole range of CERN's activities from pure physics to accelerator and detector R&D. This is a necessary condition not only to make the LHC a success as the highest priority during the next few years, but also for Europe to continue its leading role in the quest to push further the high energy frontier in the future. That will require even more challenging and more complex facilities which will only be possible if built as unique and complementary in world-wide collaborations.
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MOZCH01	Technologies for Electron-positron Linear Colliders	collider, electron, luminosity, klystron	26
	S.D. Holmes Fermilab, Batavia, Illinois
	High energy electron-positron Linear Collider designs based on room temperature and superconducting technologies have been developed and are currently under consideration by the International Technology Recommendation Panel. This paper will review the requirements and state of development of technologies required to support a linear collider meeting the performance goals outlined by the world high energy physics community. In addition it will summarize the cold/warm comparative study completed in the U.S. with particular emphasis on unique aspects related to availability and risk analysis.
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MOZCH02	Start to End Simulations of Low Emittance Tuning and Stabilization	simulation, luminosity, collider, linac	31
	P. Tenenbaum, A. Seryi, M. Woodley SLAC, Menlo Park, California D. Schulte CERN, Geneva N.J. Walker DESY, Hamburg G.R. White Queen Mary University of London, London
	The principal beam dynamics challenge to the subsystems between the damping ring and the collision point of future linear colliders is expected to be the tuning and stabilization required to preserve the transverse emittance and to collide nanometer-scale beams. Recent efforts have focused on realistically modelling the operation and tuning of this region, dubbed the Low Emittance Transport (LET). We report on the development of simulation codes which permit integrated simulation of this complex region, and on early results of these simulations. Future directions of LET simulation are also revealed.
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MOOCH03	Status of a Linac RF Unit Demonstration for the NLC/GLC X-band Linear Collider	linac, collider, klystron, feedback	42
	D.C. Schultz, C. Adolphsen, D.L. Burke, J. Chan, S. Doebert, V.A. Dolgashev, J.C. Frisch, R.K. Jobe, D.J. McCormick, C.D. Nantista, J. Nelson, M.C. Ross, T.J. Smith, S.G. Tantawi SLAC, Menlo Park, California D.P. Atkinson LLNL, Livermore, California Y.H. Chin, S. Kazakov, A. Lounine, T. Okugi, N. Toge KEK, Ibaraki
	Designs for a future TeV scale electron-positron X-band linear collider (NLC/GLC) require main linac units which produce and deliver 450 MW of rf power at 11.424 GHz to eight 60 cm accelerator structures. The design of this rf unit includes a SLED-II pulse compression system with a gain of approximately three at a compression ratio of four, followed by an overmoded transmission and distribution system. We have designed, constructed, and operated such a system as part of the 8-Pack project at SLAC. Four 50 MW X-band klystrons, running off a common 400 kV solid-state modulator, drive a dual-moded SLED-II pulse compression system. The compressed power is delivered to structures in the NLCTA beamline. Four 60 cm accelerator structures are currently installed and powered, with four additional structures and associated high power components available for installation late in 2004. We describe the layout of our system and the various high-power components which comprise it. We also present preliminary data on the processing and initial high-power operation of this system.
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MOPLT107	Nanosecond-timescale Intra-bunch-train Feedback for the Linear Collider: Results of the FONT2 Run	feedback, collider, kicker, dipole	785
	P. Burrows, T. Hartin, S.M. Hussain, S. Molloy, G.R. White Queen Mary University of London, London C. Adolphsen, J.C. Frisch, L. Hendrickson, R.K. Jobe, T. Markiewicz, D.J. McCormick, J. Nelson, M.C. Ross, S. Smith, T.J. Smith SLAC, Menlo Park, California R. Barlow, M. Dufau, A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Myatt, C. Perry OXFORDphysics, Oxford, Oxon
	We report on experimental results from the December 2003/January 2004 data run of the Feedback On Nanosecond Timescales (FONT) experiment at the Next Linear Collider Test Accelerator at SLAC. We built a second-generation prototype intra-train beam-based feedback system incorporating beam position monitors, fast analogue signal processors, a feedback circuit, fast-risetime amplifiers and stripline kickers. We applied a novel real-time charge-normalisation scheme to account for beam current variations along the train. We used the system to correct the position of the 170 nanosecond-long bunchtrain at NLCTA, in both 'feed forward' and 'feedback' modes. We achieved a latency of 53 nanoseconds, representing a significant improvement on FONT1 (2002), and providing a demonstration of intra-train feedback for the Linear Collider.
MOPLT133	Beam Loading and Higher-band Longitudinal Wakes in High Phase Advance Traveling Wave Accelerator Structures for the GLC/NLC	beam-loading, impedance, simulation, higher-order-mode	848
	R.M. Jones, V.A. Dolgashev, Z. Li, T.O. Raubenheimer SLAC, Menlo Park, California
	A multi-bunch beam traversing traveling wave accelerator structures, each with a 5pi/6 phase advance is accelerated at a frequency that is synchronous with the fundamental mode frequency. As per design, the main interaction occurs at the working frequency of 11.424 GHz. However, modes with frequencies surrounding the dominant accelerating mode are also excited and these give rise to additional modal components to the wakefield. Here, we consider the additional modes in the context of X-band accelerator structures for the GLC/NLC (Global Linear Collider/Next Linear Collider). Finite element simulations, mode-matching and circuit models are employed in order to calculate the wakefield.
MOPLT134	X-Band Linear Collider R&D in Accelerating Structures through Advanced Computing	simulation, collider, impedance, damping	851
	Z. Li, N.T. Folwell, L. Ge, A. Guetz, V. Ivanov, K. Ko, M. Kowalski, L. Lee, C.-K. Ng, G. Schussman, R. Uplenchwar SLAC, Menlo Park, California M. Wolf University of Illinois, Urbana
	The X-band linear collider design, GLC/NLC, requires accelerating structures in the main linac to operate at 65 MV/m and to be able to control emittance growth due to dipole wakefields generated by 100 micron bunch trains. The approach to high gradient has focused mainly on testing structures for acceptable breakdown rates at the desired gradient through experiments since the problem is analytically challenging. In suppressing dipole wakefields, the damped, detuned structure (DDS) has shown capable of meeting design requirements but the analysis using equivalent circuits has thus far been limited to the lowest two dipole bands. This paper describes a computational approach that addresses these design issues through large-scale simulations, using a suite of parallel electromagnetic codes developed under the DOE SciDAC Accelerator Simulation Project. Numerical results on peak field calculation, dark current generation, and wakefield computation will be presented on the H60VG4S17 DDS structure, considered to be the baseline design for the NLC.
MOPLT136	Reliability Simulations for a Linear Collider	simulation, collider, luminosity, positron	857
	N. Phinney, T.M. Himel, M.C. Ross SLAC/NLC, Menlo Park, California P. Czarapata, H. Edwards, M. Huening Fermilab, Batavia, Illinois
	A new flexible tool for evaluating accelerator reliability was developed as part of the US Linear Collider Technology Comparison Study. The linear collider designs considered were based on the GLC/NLC X-band and TESLA Superconducting proposals, but modified to meet the US physics requirements. To better model some of the complexities of actual operation, a simulation program was written, which included details such as partial fixes or workarounds, hot-swappable repairs, multiple simultaneous repairs, cooldown periods before access, staged recovery from an outage, and both opportunistic and scheduled machine development. The main linacs and damping rings were modeled in detail with component counts taken from the designs, and using MTBFs and MTTRs from existing accelerator experience. Other regions were assigned a nominal overall failure rate. Variants such as a single tunnel or conventional positron source were also evaluated, and estimates made of the sensitivity to recovery or repair times. While neither design was predicted to be sufficiently reliable given present experience, the required improvements were estimated to increase the overall project cost by only a few percent.
TUPKF066	34 Ghz, 45 MW Pulsed Magnicon: First Results	gun, electron, plasma, cathode	1096
	O.A. Nezhevenko, V.P. Yakovlev Omega-P, Inc., New Haven, Connecticut J.L. Hirshfield, M.A. LaPointe Yale University, Physics Department, New Haven, CT
	A high efficiency, high power magnicon at 34.272 GHz has been designed and built as a microwave source to develop RF technology for a future multi-TeV electron-positron linear collider. To develop this technology, this new RF source is being perfected for necessary tests of accelerating structures, RF pulse compressors, RF components, and to determine limits of breakdown and metal fatigue. After preliminary RF conditioning of only about 200000 pulses, the magnicon produced an output power of 10.5 MW in 0.25 microsecond pulses, with a gain of 54 dB. Slotted line measurements confirmed that the output was monochromatic to within a margin of at least 30 dB.
WEILH03	Industrial Response to RF Power Requirements	power-supply, collider, monitoring, feedback	202
	M. Wilcox e2v technologies, Chelmsford, Essex
	Today, high-energy physics machines are broadly speaking of two kinds. Some machines are dedicated to providing a service using particle acceleration as an intermediate step (light sources, neutron spallation sources, cancer therapy equipment etc.)and occasionally, particle colliders are built in which the particles are used directly to probe the nature and origin of matter. The latter machines have developed to a point where the technology needed is often at the extreme edge of what is understood, let alone of what is currently achievable. In addition the scope of supply and the level of equipment integration demanded of industry is increasing as RF skills become scarcer. This reduces the supplier base so placing greater demands on those remaining. To help offset this problem, companies should be brought 'inside' the project team at an early stage of the machine design so that better account can be taken of limitations, preferences and competing obligations that the companies may have. A more collaborative approach should result in projects being completed in a shorter time, to a lower cost, and with a more certain outcome.
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WEPKF047	A Super Strong Adjustable Permanent Magnet for the Final Focus Quadrupole in a Linear Collider	quadrupole, permanent-magnet, collider, simulation	1708
	T. Mihara, Y. Iwashita Kyoto ICR, Uji, Kyoto E. Antokhin, M. Kumada NIRS, Chiba-shi C.M. Spencer SLAC, Menlo Park, California E. Sugiyama NEOMAX Co., Ltd., Mishima-gun, Osaka
	A super strong magnet, which utilizes permanent magnet material and saturated iron, is considered as a candidate for the final focus quadrupole in a linear collider beamline. This modified Halbach magnet configuration can have a higher magnetic field gradient than a normal permanent magnet quadrupole (PMQ) or electromagnet. There are some issues to be solved if a PMQ is to be used as a final focus quadrupole: the variation of its strength with temperature and the need for the field strength to be deliberately changed. One can use special temperature compensation material to improve the temperature dependence with just a small decrease in field gradient compared to a magnet without temperature compensation. The required field variability can be obtained by slicing the magnet into pieces along the beamline direction and rotating these slices. Results of performance measurements on the PMQ with variable strength will be reported including the realization of the temperature compensation technique.
WEPKF048	Characteristics of Ground Motion at KEK and SPring-8	ground-motion, site, power-supply, collider	1711
	Y. Nakayama, T. Ito JPOWER, Kanagawa-ken S. Matsui, C. Zhang JASRI/SPring-8, Hyogo R. Sugahara, S. Takeda, H. Yamaoka, M. Yoshioka KEK, Ibaraki S. Yamashita University of Tokyo, Tokyo
	Authors Y. Nakayama, T. Ito, (JPOWER); R. Sugahara, S. Takeda, H.Yamaoka, M.Yoshioka (KEK); S.Matsui, C.Zhang (SPring-8); S. Yamashita (ICEPP): Abstract Stability of ground is preferable for accelerator beam operation. We have measured ground motion of ground at the KEKB and SPring-8 site, where the ground has quite different characteristics each other. In this paper, some of analysis results are shown, and the characteristics of the ground motion at the KEKB site and those at the Spring-8 site are compared.
WEPKF076	Solid-state Marx Bank Modulator for the Next Linear Collider	klystron, cathode, pulsed-power, collider	1783
	M.A. Kempkes, F.O. Arntz, J.A. Casey, M.P.J. Gaudreau Diversified Technologies, Inc., Bedford
	The Next Generation Linear Collider (NLC) will require hundreds to thousands of pulse modulators to service more than 3300 klystrons. DTI recently investigated the use of a solid-state Marx switch topology for the NLC, and has transitioned this work into the development of a full-scale, 500 V solid state Marx system. Combined with recent advances in semiconductor technology and packaging, these efforts have moved the performance of the Marx pulser far ahead of early estimates. The Marx pulser eliminates the pulse transformer, which is associated with significant loss of performance and a 15-20% penalty in the efficiency of a conventional modulator. The increase in efficiency attributable to the Marx topology can account for over $100M in power cost savings over ten years of NLC operation, an amount comparable to the acquisition costs of the pulsed power systems. In this paper, DTI will discuss the design and development of the Marx Bank modulator. Its performance scales to 125 ns risetime (10-90%) for either a 500 kV, 265 A pulse (for one klystron), or a 500 kV, 530 A pulse (for two klystrons). The use of a unique, common mode inductive charging system allows transfer of filament power without separate isolation transformers.
WEPKF081	Prototype Development Progress toward a 500kV Solid State Marx Modulator	klystron, cathode, linac, simulation	1792
	G. Leyh SLAC, Menlo Park, California
	Recent advances in high voltage IGBT capabilities have made possible a range of novel solid-state modulator concepts that were unthinkable a decade ago. At present, there are two prototype solid-state modulator designs under evaluation at SLAC – A conventional pulse-transformer design using an 80kV solid-state switch in place of a thyratron, and an 'induction modulator', which uses a stack of magnetic cores to couple many paralleled primary windings to a common secondary winding. Both of these prototype modulators are currently driving actual klystron loads at SLAC. Another promising solid-state modulator concept still in the early stages of development is the Marx configuration – where an array of stacked modules generates high-voltage output pulses directly from a low DC input supply voltage. This scheme eliminates the large and costly magnetic cores inherent in the other two designs, resulting in a considerably simpler and cheaper mechanical solution. The main disadvantage to this approach is that the individual Marx sections must float at high voltages, complicating the distribution of power and timing signals. Several research groups have produced limited scale Marx prototypes in recent years. The largest prototype built to date [DTI] generates an output pulse of approximately 50kV, with plans to eventually move to higher voltage levels. This paper examines in closer detail the practical advantages and pitfalls of a solid-state Marx configuration, and explores a design approach with emphasis on performance, wall-plug efficiency, cost of manufacture, availability and ease of service. The paper presents electrical diagrams, mechanical CAD layout and preliminary prototype test data.
THPLT036	New Discretization Scheme for Wake Field Computation in Cylindrically Symmetric Structures	alignment, collective-effects, simulation, collider	2559
	R. Hampel, T. Weiland, I. Zagorodnov TEMF, Darmstadt
	Collective effects due to wake fields are a limiting factor in almost every new front line accelerator. Since the early 80's computer codes such as TBCI and MAFIA have been developed for computing wake fields in realistic accelerator structures. With the advent of linear collider studies and small wavelength FEL projects these codes had to face a severe limitation. For the very short bunches in these new accelerators combined with the need for an analysis of very long sections the discrete dispersion became a serious drawback. This effect of having only discrete field values rather than continous ones can be overcome by special algorithms such as semi-implicit integrators as used e.g. in the wake field code ECHO. In this paper we present a new explicit approach which combines the advantage of explicit algorithms (fast) with the absence of dispersion in beam direction.