Technology, Components, Subsystems

Technology, Components, Subsystems, Other

Paper	Title	Page
TUP85	J-PARC Linac Alignment	474
	M. Ikegami, C. Kubota, F. Naito, E. Takasaki, H. Tanaka, K. Yoshino KEK, Ibaraki H. Ao, T. Itou JAERI/LINAC, Ibaraki-ken K. Hasegawa, T. Morishita, N. Nakamura, A. Ueno JAERI, Ibaraki-ken
	J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac, and its total length is more than 400 m including the beam transport line to the succeeding RCS (Rapid Cycling Synchrotron). In high-current proton accelerators, precise alignment of accelerator components is indispensable to reduce uncontrolled beam loss and beam quality deterioration. In this paper, planned schemes for the linac alignment is presented together with instrumentation for the long-term ground-motion watching.
TUP86	Coupler Development and Gap Field Analysis for the 352 MHz Superconducting CH-Cavity	477
	H. Liebermann, H. Podlech, U. Ratzinger, A.C. Sauer IAP, Frankfurt-am-Main
	The cross-bar H-type (CH) cavity is a multi-gap drift tube structure based on the H-210 mode currently under development at IAP Frankfurt and in collaboration with GSI. Numerical simulations and rf model measurements showed that the CH-type cavity is an excellent candidate to realize s.c. multi-cell structures ranging from the RFQ exit energy up to the injection energy into elliptical multi-cell cavities. The reasonable frequency range is from about 150 MHz up to 800 MHz. A 19-cell, β=0.1, 352 MHz, bulk niobium prototype cavity is under development at the ACCEL-Company, Bergisch-Gladbach. This paper will present detailed MicroWave Studio simulations and measurements for the coupler development of the 352 MHz superconducting CH cavity. It will describe possibilities for coupling into the superconducting CH-Cavity. The development of the coupler is supported by measurement on a room temperature CH-copper model. We will present the first results of the measurements of different couplers, e.g. capacitive and inductive couplers, at different places of the CH Cavity.
TUP87	Technologies of The Peripheral Equipments of The J-PARC DTL1 for the Beam Test	480
	K. Yoshino, Y. Fukui, E. Kadokura, T. Kato, C. Kubota, F. Naito, E. Takasaki, H. Tanaka KEK, Ibaraki T. Itou JAERI/LINAC, Ibaraki-ken
	First beam test of the DTL1 was performed in November of 2003 at KEK site. A 30 mA H- beam was successfully accelerated from 3 to 19.7 MeV. In order to prepare the beam test, various peripheral equipments were developed: the electrode plates for connecting the hollow-conductor coil and the power cable were developed since quadrupole electromagnets are built in all DTs (77 sets) of the DTL1, the water-cooled multiconductor copper tube (Control Copper Tube) were used as the power cable from the electrode plate to power supply, and the interlock system assembled by PLCs (Programmable Logic Controller) was also prepared for the surveillance of many cooling channel.
TUP88	CLIC Magnet Stabilization Studies	483
	S. Redaelli, R.W. Assmann, W. Coosemans, G. Guignard, D. Schulte, I. Wilson, F. Zimmermann CERN, Geneva
	One of the main challenges for future linear colliders is producing and colliding high energy e+e- beams with transverse spot sizes at the collision point in the nanometre range. Preserving small emittances along several kilometres of linac requires the lattice quadrupoles to be stable to the nanometre level. Even tighter requirements are imposed on the stability of the final focus quadrupoles, which have to be stable to a fraction of the colliding beam size to reliably steer the opposing beams in collision. The Compact LInear Collider (CLIC), presently under investigation at CERN, aims at colliding e+e- beams with a vertical spot size of 0.7 nm, at a centre-of-mass energy of 3 TeV. This requires a vertical stability to the 1.3 nm level for the 2600 linac quadrupoles and to the 0.2 nm level for the two final focus quadrupoles. The CLIC Stability Study has demonstrated for the first time that CLIC prototype quadrupoles can be stabilized to the 0.5 nm level in a normal working area on the CERN site. Detailed tracking simulations show that with this level of stability, approximately 70% of the CLIC design luminosity would be achieved. This paper summarizes the work and the achievements of the CLIC Stability Study.
	Transparencies
TUP89	Static Absolute Force Measurement for Preloaded Piezoelements Used for Active Lorentz Force Detuning System	486
	S. P. Sekalski, A. Napieralski, S. P. Sekalski TUL, Lodz A. Bosotti INFN/LASA, Segrate (MI) M. Fouaidy IPN, Orsay L. Lilje, S. Simrock DESY, Hamburg R. Paparella, P.F. Puricelli INFN Milano, Milano
	To reach high gradients in pulsed operation of superconducting (SC) cavities an active Lorentz force detuning compensation system is needed. For this system a piezoelement can be used as an actuator (other option is a magnetostrictive device). To guarantee the demanded lifetime of the active element, the proper preload force adjustment is necessary. To determine this parameter an absolute force sensor is needed which will be able to operate at cryogenic temperatures. Currently, there is no calibrated commercial available sensor, which will be able to measure the static force in such an environment. The authors propose to use a discovered phenomenon to estimate the preload force applied to the piezoelement. The principle of the proposed solution based on a shape of impedance curve, which changes with the value of applied force. Especially, the position of resonances are monitored. No need of specialized force sensor and measurement in-situ are additional advantages of proposed method.
TUP98	The Finite State Machine for Klystron Operation for VUV-FEL and European X-FEL Linear Accelerator	510
	W. Cichalewski, B. Koseda, A. Napieralski TUL, Lodz F.-R. Kaiser, S. Simrock DESY, Hamburg
	In order to provide a pulsed RF power signal that fulfills all designers and users demands the work on power supplies, pulse transformers, waveguides and klystrons has to be well coordinated. Because operators not engineers will operate mention user facility therefore software has to be implemented in order to automate the enormous quantity of hardware operation accompanying regular operation of linear accelerator collider. A finite state machine is adequate formal description of reactive systems that has become starting point for designing our control software. To present the complexity of the task that establishing FSM for Klystron system would be, one has to become acquainted with complexity of the system itself. Therefore this article describes the construction and principles of the klystron and modulator as well as ideas concerning the implementation of a FSM for such a system.
TH103	Summary of the Argonne Workshop on High Gradient RF	564
	J. Norem ANL, Argonne, Illinois
	Workshop on High Gradient rf was held at Argonne from October 7 - 9, 2003. This workshop reviewed the problems encountered when a number of accelerator technologies approached the high gradient limits. The aim of the workshop was to involve materials scientists and try to look at trigger mechanisms and surface interactions, in addition to reviewing progress. Talks were presented on superconducting rf, progress with high and low frequency copper cavities, and dielectrics. The focus was on both experimental and theoretical aspects of the problem. The overall picture presented at the workshop will be summarized.
	Transparencies
TH202	Review of Fast Beam Chopping	578
	F. Caspers CERN, Geneva
	Several types of fast beam chopping systems in use or under construction are presented. Emphasis is given to their specific technologies and in particular their various fields of application. Important parameters are duty cycle, rise-and falltime, ringing and overall bandwidth. Certain systems have very specific driver concepts since the generation of multi kW peak power with nanosecond transients, high repetition rate and very good pulse shape fidelity is not a trivial issue. The design of driver amplifier and actual chopper structure are not always mutually independent and thus some of the limiting aspects will be discussed.
	Transparencies
THP35	Development of a Non-Magnetic Inertial Sensor for Vibration Stabilization in a Linear Collider	681
	J. Frisch, A. Chang, V. Decker, L. Hendrickson, T. Markiewicz, R. Partridge, A. Seryi SLAC, Menlo Park, California D. Eric, T. Himel SLAC/NLC, Menlo Park, California
	One of the options for controlling vibration of the final focus magnets in a linear collider is to use active feedback based on accelerometers. While commercial geophysics sensors have noise performance that substantially exceeds the requirements for a linear collider, they are physically large, and cannot operate in the strong magnetic field of the detector. Conventional nonmagnetic sensors have excessive noise for this application. We report on the development of a non-magnetic inertial sensor, and on a novel commercial sensor both of which have demonstrated the required noise levels for this application.
	Transparencies
THP36	Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet	684
	J. Frisch, A. Chang, V. Decker, L. Hendrickson, T. Markiewicz, R. Partridge, A. Seryi SLAC, Menlo Park, California E. Eric, L. Eriksson, T. Himel SLAC/NLC, Menlo Park, California
	The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.
THP37	Approaches to Beam Stabilization in X-Band Linear Colliders	687
	J. Frisch, L. Hendrickson, T. Markiewicz, A. Seryi SLAC, Menlo Park, California P. Burrows, S. Molloy, G. White Queen Mary University of London, London C. Perry OXFORDphysics, Oxford, Oxon T.O. Raubenheimer, T. Thomas SLAC/NLC, Menlo Park, California
	In order to stabilize the beams at the interaction point, the X-band linear collider proposes to use a combination of techniques: inter-train and intra-train beam-beam feedback, passive vibration isolation, and active vibration stabilization based on either accelerometers or laser interferometers. These systems operate in a technologically redundant fashion: simulations indicate that if one technique proves unusable in the final machine, the others will still support adequate luminosity. Experiments underway for all of these technologies, have already demonstrated adequate performance.
THP38	High Precision Survey and Alignment of Large Linear Accelerators	690
	J. Prenting, M. Schlösser DESY, Hamburg J. Green, G. Grzelak, A. Mitra, A. Reichold OXFORDphysics, Oxford, Oxon A. Herty CERN, Geneva
	For the future linear accelerator TESLA the demanded accuracy for the alignment of the components is 0.5 mm horizontal and 0.2 mm vertical, both on each 600 m section. Other accelerators require similar accuracies. These demands can not be fulfilled with open-air geodetic methods, mainly because of refraction. Therefore the RTRS (Rapid Tunnel Reference Surveyor), a measurement train performing overlapping multipoint alignment on a reference network is being developed. Two refraction-free realizations of this concept are being developed at the moment: the first one (GeLiS) measures the horizontal co-ordinates using stretched wires, combined with photogrammetric split-image sensors in a distance measurement configuration. In areas of the tunnel where the accelerator is following the earth curvature GeLiS measures the height using a new hydrostatic leveling system. The second concept (LiCAS) is based on laser straightness monitors (LSM) combined with frequency scanning interferometry (FSI) in an evacuated system. LiCAS measures both co-ordinates with respect to its LSM-beam and is thus suitable for geometrically straight tunnel sections. Both measurement systems will be placed on a train, which could do the reference survey autonomously.
THP94	Cold Tests of a 160 MHz Half-Wave Resonator	821
	R. Stassen, R. Maier FZJ/IKP, Jülich R. Eichhorn, F. M. Esser, B. Laatsch, G. Schug, H. Singer FZJ, Jülich
	The number of polarized particle in the cooler synchrotron COSY is limited by the present injector system. A new linac was projected based on superconductive half-wave resonators to fill COSY up to the space charge limit. The first prototype of a 160 MHz Half-Wave Resonator (HWR) has been built and tested. RF-measurements in CW as well as in a pulsed operation will be presented. A second prototype with a slightly different way of fabrication will be completed soon. All measurements have been done using the new 4 kW loop-coupler. The use of a cold window allows to change the coupling from 1· 106 to 1· 1010 without any risk of contamination. The mechanical tuner consisting of a stepper motor driven coarse tuner and a fast piezo system to compensate the Lorentz-Force detuning has successfully integrated into the vertical test-cryostat.
THP95	Electro Polishing of Niobium Cavities at DESY	824
	A. Matheisen, L. Lilje, H. Morales, B. Petersen, M. Schmoekel, N. Steinhau-Kühl DESY, Hamburg
	At DESY a facility for electro polishing (EP) of the super conducting (s.c.) TESLA/TTF cavities have been built and is operational since summer 2003. The EP infrastructure is capable to handle single-cell structures and the standard TESLA/ TTF nine-cell cavities. Several electro polishing processes have been made since and acceleration voltage up to 40 MV/m have been reached in nine cell structures. We report on measurements and experiences gained since 2003 as well as on handling procedures developed for the preparation of electro polished resonators. Specific data like heat production, variation of current density and bath aging will be presented. Another important point for reproducible results is the quality control of the electro polishing process. First quality control steps to be implanted in the EP procedure for large-scale production will be described.
FR102	Muon Ionization Cooling Experiment (MICE)	832
	M.S. Zisman LBNL, Berkeley, California
	There is presently considerable activity worldwide on developing the technical capability for a “neutrino factory” based on a muon storage ring and, a muon collider. Muons are obtained from the decay of pions produced when an intense proton beam hits a high-Z target, so the initial muon beam has a large 6-dimensional phase space. To increase the muons’ phase-space density, we use ionization cooling, which is based on energy loss in an absorber, followed by re-acceleration with high-gradient, normal-conducting RF cavities. The absorber of choice is liquid hydrogen to minimize multiple scattering. A superimposed solenoidal focusing channel contains the muons. Although the physics is straightforward, the technology and its implementation are not. The international MICE collaboration will demonstrate ionization cooling of a muon beam in a short section of a typical cooling channel. The experiment is approved for operation at Rutherford Appleton Lab. We will measure the cooling effects of various absorber materials at various initial emittance values using single-particle counting techniques. The experiment layout and goals will be discussed, along with the status of component R&D.
	Transparencies