| Paper | Title | Other Keywords | Page | ||
|---|---|---|---|---|---|
| MOPLT045 | Vacuum Induced Backgrounds in the New HERA Interaction Regions | target, wiggler, feedback, extraction | 647 | ||
|
After the rebuild of the HERA interaction regions the experimental detectors were limited by beam induced backgrounds. Four types of background mechanisms were observed and identified - proton gas scattering, lepton gas scattering, synchrotron radiation and proton beam-halo losses. With some refined beam steering methods it was possible to tune the synchrotron radiation background to acceptable limits. The remaining most important effect was the scattering of the beam particles, mostly the protons, at the residual gas. In this contribution we describe our systematic attempts to investigate the complex behavior of the beam gas background and the measures taken to improve the situation. This includes dynamic pressure profile simulations and measurements, experimental determination of the background sensitivity profile along the beamline, the pressure development with current and time, and residual gas analysis. The background conditions were finally improved due to long term conditioning with beam, modifications of internal masks which were heated by higher order mode losses and moderate improvements of the pumping speed at strategic locations.
|
|
|
||
| MOPLT046 | Overcoming Performance Limitations due to Synchrobetatron Resonances in the HERA Electron Ring | target, wiggler, extraction, undulator | 650 | ||
|
The HERA Electron Ring was suffering from strong synchrobetatron resonances which have been particularly detrimental after the HERA luminosity upgrade because of a reduced sychrotron tune due to stronger transverse focusing and a shift in the damping distribution in favor of transverse damping. It turned out to be most difficult to store a beam at the preferred working point for high electron spin polarization between the 2nd and the 3rd synchro-betatron satellite of the horizontal integer resonance. A comparative study of the resonance strength did not reveal any significant additional disadvantage of the new beam optics. However, a mechanism driven by closed orbit distortions was discovered which can increase the width of the resonance Qx+2Qs=0 by a large factor. This explains the operational difficulties. The remedy against this effect is quite straight forward. The Fourier component of the closed orbit near the horizontal tune must be avoided. This is enforced in HERA operations by rigerous orbit corrections and an orbit feedback system which reproduces well-corrected orbits reliably. Synchrobetatron resonances do not constitute a performance limitation of polarized lepton proton collisions in HERA any more.
|
|
|
||
| MOPLT047 | Lattice Design Study for HESR | wiggler, extraction, undulator, scattering | 653 | ||
|
The important feature of High Energy Storage Ring is the combination of phase space cooled beams with internal targets, which allows to reach high luminosities up to 2*1032cm-2s-1. However, the requirement to have the strongly focused beam on the target causes the high chromaticity value on the target straight section and as in result to the squeezing of dynamic aperture after sextupole correction of the chromaticity. Simultaneously, the momentum-compaction factor is one of the most important characteristics of an accelerator, which defines the collective instability threshold. Therefore, the HESR lattice has to have the following features: low or negative momentum compaction factor, dispersion free straight sections, convenient method to correct the chromaticity by the sextupoles, sufficiently large dynamic aperture. In this work we develop lattice, which meets all these requirements for HESR.
|
|
|
||
| MOPLT048 | High Current Switch-mode Power Converter Prototype for LHC Project 6kA, 8V | wiggler, extraction, undulator, scattering | 656 | ||
|
For the Large Hadron Collider (LHC) accelerator being constructed on the CERN site, very precise variable DC currents are required. The company JEMA had during year 2002, designed, manufactured and tested a power converter prototype according to CERN specifications, particularly demanding in terms of dc stability and dynamic response. The power converter is formed by four sub-converters 8V, 2kA in parallel. Isolation between mains input and magnet load is at high frequency done, 40 kHz, which means a volume reduction and better mains perturbations rejection. IGBT inverter soft switch-mode power conversion in ZVS operation reduces dramatically commutation losses, increasing total efficiency of the power converter. The sub-converter, regulated by a wide band width current loop in ACC mode, follows the current reference calculated by the overall voltage loop, providing a good sharing of the output currents and high output stability. The design of the water cooled power converter, results in a very reduce volume and modular structure, providing the system a very flexible exchangeability. The power converter was tested and accepted by CERN into year 2003, some minor points were left to be adjusted during the pre-series stage.
|
|
|
||
| MOPLT049 | A Very High-beta Optics to be used for an Absolute Luminosity Determination with Forward Detectors in ATLAS | wiggler, extraction, undulator, resonance | 659 | ||
|
Atlas detector at the LHC pursues a number of different approaches to obtain an estimate of the absolute luminosity. Measuring elastic scattering at very small angles (3 mu rad) represents a different and complimentary approach that will improve the precision of the final luminosity estimate. In this paper we show the required very hihg-beta optics, detector acceptance studies, and running conditions and calculated performance for the proposed forward detectors located near the ATLAS interaction region.
|
|
|
||
| MOPLT050 | High-beta and Very High-beta Optics for LHC | wiggler, extraction, undulator, resonance | 662 | ||
|
New high-beta and very high-beta optics has been sought in order to find the best possible configuration for measuring total cross section in TOTEM and absolute luminosity in ATLAS. They are based on nominal powering scheme of the low-beta triplet. A list of the various possible solution is given in this report. A particularly interesting solution has been found for a case where the phase advance in both planes at the detector location are close to pi/2.
|
|
|
||
| MOPLT051 | Experimental Characterization of PEP-II Luminosity and Beam-beam Performance | wiggler, extraction, undulator, resonance | 665 | ||
|
The beam-beam performance of the PEP-II B-Factory has been studied by simultaneously measuring the instantaneous luminosity, the horizontal and vertical e+ and e- beam sizes in the two rings, and the spatial extent of the luminous region as extracted from BaBar dilepton data. These quantities, as well as ring tunes, beam lifetimes and other collider parameters are recorded regularly as a function of the two beam currents, both parasitically during routine physics running and in a few dedicated accelerator physics experiments. They are used to quantify, project, and ultimately improve the PEP-II performance in terms of achieved beam-beam parameters, dynamic-beta enhancement, and current-dependence of the specific luminosity.
|
|
|
||
| MOPLT052 | Emittance Growth and Beam Lifetime Limitations due to Beam-beam Effects in e+e- Storage Ring Colliders | wiggler, extraction, undulator, resonance | 668 | ||
|
In this paper we give analytical expressions for the maximum beam-beam parameter and related beam-beam limited beam lifetime in e+e- storage ring colliders. After analysing the performances of existing or existed machines, we make some discussions on the parameter choice for the Super-B factory design.
|
|
|
||
| MOPLT053 | On Parasitic Crossings and their Limitations to e+e- Storage Ring Colliders | wiggler, extraction, undulator, resonance | 671 | ||
|
We treat the problem of parasitic crossing in e+e- storage ring colliders analytically. Analytical formulae for the beam lifetime limited by the combined effects of beam-beam interactions at interaction point and at parasitic crossings are derived, and applied to the by-2 colliding mode of PEP-II low energy ring.
|
|
|
||
| MOPLT054 | High Current Operation of Pre-bunching Cavities in the CTF3 Accelerator | wiggler, extraction, undulator, resonance | 674 | ||
|
In the framework of the CLIC studies for a 3 TeV centre of mass linear collider the CLIC Test Facility-3 accelerator (CTF3) is developed to validate the novel concept of CLIC drive beam generation. The front end of the CTF3 linac uses a 140 kV thermionic gun capable to deliver a beam with currents of up to 10 A during 1.5 microseconds. Theμtime structure of this beam is generated with two standing wave single-cell 3 GHz pre-buncher cavities. The high current demands special care in the design of the pre-bunchers to preserve beam quality and transmission. A particular concern was beamloading in the second pre-buncher. In this paper, the design and the conditioning of the pre-bunchers are reported but the main focus is on the commissioning with the electron beam, which showed unexpected results. Indeed, contrary to our expectations, the unbunched beam seems to induce a kind of beamloading in the first pre-buncher while the second one shows none.
|
|
|
||
| MOPLT055 | RF Excitation of Linear and Curved Sections of the CRFQ Project | wiggler, extraction, undulator, resonance | 677 | ||
|
The Circular Radiofrequency Quadrupole is basically a Linear Radio-Frequency Quadrupole completely bent on a circle. A 30-keV prototype is being presently designed and manufactured for testing of the fundamental principles within the scope of a collaboration between BNL and Italian research centers. The storage ring is made of a proton source, a Linear RfQ section 70 cm long, for injection and matching, and eight Curved sections also each about 70 cm long. The proton beam is provided by a modified RF source with electrostatic acceleration at the emittance, intensity and energy required by the beam dynamics.The design of the initial linear prototype is based on a 4-rods geometry having a beam gap diameter of 10mm, and circular 10mm diameters rods. The sector is placed in a 150mm diameter pipe, making it as a very compact structure. The dimensions of the device are adjusted to resonate at 202.56 MHz. A RF power source will be soon available to test the device. The paper describes the compact RF cells arrangement in the design of the two sections.
|
|
|
||
| MOPLT056 | Feasibility Study for a Very High Luminosity Phi-factory | wiggler, extraction, undulator, resonance | 680 | ||
|
Particle factories are facing their future by looking at the possibility of upgrading the luminosity by orders of magnitude. The upgrade challenges are more stringent at lower energies. Double symmetric rings, enhanced radiation damping, negative momentum compaction and very short bunches at the collision point are the main features of a phi-factory feasibility study presented in this paper. The bunch length of few millimeters at the crossing point of the beams is obtained by applying the Strong RF Focusing principle which provides a modulation of the bunch length along the ring by means of a large momentum compaction factor together with a very high RF gradient. The collider design fits the existing DAFNE infrastructures with completely rebuilt rings and upgraded injection system.
|
|
|
||
| MOPLT057 | Proposal of a Strong RF Focusing Experiment at DAFNE | wiggler, extraction, undulator, resonance | 683 | ||
|
The strong RF focusing is a recently proposed technique to obtain short bunches at the interaction point in the next generation colliders. A large momentum compaction factor together with a very high RF gradient across the bunch provide a modulation of the bunch length along the ring, which can be minimized at the Interaction Point (IP). No storage ring has been so far operated in such a regime, since it requires uncommonly high synchrotron tune values. In this paper we present the proposal of creating the experimental conditions to study the strong RF focusing in DAFNE. The proposed machine lattice providing the required high momentum compaction value, the upgrade of the RF system including the installation of a multi-cell superconducting cavity, the upgrade of the cryogenic plant and a list of the possible beam experiments are illustrated and discussed.
|
|
|
||
| MOPLT058 | Status of CTF3 Stretcher-compressor and Transfer Line | wiggler, extraction, vacuum, undulator | 686 | ||
|
The first part of the CTF3 transfer line is under installation. It includes a chicane which, because of its very flexible lattice and large aperture vacuum chamber, can change the bunch length in a wide range. The chicane can be used as a stretcher to lengthen the pulses coming from the linac in order to reduce the coherent synchrotron radiation (CSR) in the recombination rings. A possible use as a bunch compressor is also foreseen in order to make CSR experiments and to characterize beam instrumentation. This paper describes the final design of the vacuum chambers, including beam diagnostics components, and their laboratory tests. The installation status of the magnetic and vacuum chamber components together with the ancillary systems is reported.
|
|
|
||
| MOPLT059 | Design Options for the RF Deflector of the CTF3 Delay Loop | wiggler, vacuum, undulator, resonance | 689 | ||
|
Injection and extraction of bunch trains in the CTF3 Delay Loop for the recombination between adjacent bunch trains is performed by a specially designed RF deflector. A standing wave structure has been chosen. Three possible solutions have been studied and designed, and a comparative analysis is presented. All of them satisfy the essential requirements of the system up to the maximum foreseen energy with the existing klystron.
|
|
|
||
| MOPLT060 | New RF Measuring System for Cavity Characterization | wiggler, vacuum, undulator, resonance | 692 | ||
|
New computer based mobile measuring system for laboratory and online characterization of superconducting cavities has been put into operation at LNL. The system covers the frequency range from 80 to 350 MHz and represents a reliable, fast and precise instrument for cavity testing. The list of automatic and semiautomatic procedures includes line calibrations, frequency sweep, decay time measurement, Q(Eacc) curve acquisition and pulse conditioning.
|
|
|
||
| MOPLT061 | Design Study for Advanced Acceleration Experiments and Monochromatic X-ray Production @ SPARC | wiggler, vacuum, undulator, resonance | 695 | ||
|
We present a design study for an upgrade of the SPARC photo-injector system, whose main aim is the construction of an advanced beam test facility for conducting experiments on high gradient plasma acceleration and for the generation of monochromatic X-ray beams to be used in advanced medical applications and condensed matter physics studies. Main components of the proposed plan of upgrade are: two additional beam lines with interaction regions for synchronized high brightness electron and high intensity photon beams and the upgrade of the SPARC Ti:Sa laser system to reach a multi-TW power level (in excess of 1 J in pulse energy). Results of numerical simulations modeling the interaction of the SPARC electron beam and the counter-propagating laser beam are presented with detailed discussion of the monochromatic X-ray beam spectra generated by Compton backscattering: X-ray energies are tunable in the range 20 to 500 keV, with pulse duration from sub-ps to 30 ps. Preliminary simulations of plasma acceleration of the SPARC electron beam, generated in ultra-short bunches, via the LWF mechanism and with external injection are also shown: experiments of self-injection are also foreseen and illustrated.
|
|
|
||
| MOPLT062 | The Design of a Prototype RF Compressor for High Brightness Electron Beams | wiggler, vacuum, undulator, resonance | 698 | ||
|
The generation of sub-ps electron bunches with low transverse emittance at nC charge level is a crucial requirement in the design of injectors for short wavelength FEL's. The technique of velocity bunching has been by now experimentally proven in various laboratories, where bunches below the ps bunch length were obtained: however, preservation of a low transverse emittance after the bunch compression is still to be demonstrated. To this aim, the use a slow wave RF structure as a rectilinear compressor has been proposed in the past to overcome the inherent difficulties of magnetic compressors. In this paper we will review the work carried out in the last 2 years and focused on the design a RF compressor based on a 3 GHz slow-wave copper structure. The rationale of the conceptual design along with a description of the main experimental activities will be presented and the future application of such a scheme to the SPARC project will be discussed.
|
|
|
||
| MOPLT063 | Reconfigurable Hardware Resources in Accelerator Control Systems | wiggler, vacuum, undulator, resonance | 701 | ||
|
The development of modern accelerator control systems has taken advantage of the possibility to use standard architecture designs based on the experience gained in industrial applications. Communication buses, board formats, operating systems, network protocols and operator interface software are the main elements of this new approach. In this paper we will discuss the way to apply this method also to the design of electronic boards which call for custom design of particular circuits and capabilities. The use of FPGA based standard modules along with the possibility to customize them using a standard LabVIEW environment to obtain reconfigurable hardware resources will be presented.
|
|
|
||
| MOPLT066 | Induction Accelerating Cavity for a Circular Ring Accelerator | wiggler, vacuum, undulator, resonance | 704 | ||
|
This paper reports details of an induction accelerating cavity employed for induction synchrotron POP experiments [*] using the KEK 12GeV PS. This cavity is the first induction cavity in the history of accelerator that is used in a circular ring. We focus our attention on crucial aspects distinguished from well-know properties of RF cavity. The single cavity is capable of generating an acceleration voltage of 2.5kV with a pulse width of 250ns, which is operated at a repetition rate in the range of 667kHz - 882kHz. The cavity is driven by its own pulse modulator through a 25m long transmission cable of 125W, the end of which is connected with a matching resistance so as to minimize reflection in a wide range of frequency. Accelerating field characteristics are discussed and matching features of the cavity as a one-to-one transformer are presented. A longitudinal and transverse coupling impedance have been measured using a net-work analyzer.
|
* K.Takayama et al., 'POP Experiments of the Induction Synchrotron' in this conference |
|
||
| MOPLT067 | KEKB Performance | wiggler, vacuum, undulator, resonance | 707 | ||
|
The KEKB B-Factory is an electron-positron double ring collider working at KEK. Its peak luminosity surpassed 1034 /cm2/sec in May 2003 for the first time in the history of colliders. In this report, we summarize the history of KEKB with an emphasis of recent progress.
|
|
|
||
| MOPLT069 | Investigation of Injection for the Low-emittance Lattice with New-6.25 ohm Kicker Magnet System at the Photon Factory | injection, wiggler, vacuum, undulator | 710 | ||
|
We installed 6.25ohm traveling-wave kicker magnet in the Photon Factory to obtain a wide acceptance for the injected beam into the low-emittance lattice of the Photon Factory. We investigate the injection for the low-emittance lattice with this 6.25ohm kicker magnet system. Hence we have optical beam diagnostic systems which source point is inside of injection bump, we use this system for the investigation of injection. The pulse shape of the injection bump was measured by the optical beam profile monitor with high-speed gated camera by using a stored beam. The result of pulse shape of injection bump was agreed with the predicted one by using result of magnetic field measurement, and pulse duration was shorter than twice of revolution time. The instantaneous beam profile of injected beam was observed in turn by turn by using the same beam profile monitor system. We measure the turn by turn position of the injected beam from this observation and compare with a simulation. We also observe a smear out of beam oscillation by nonlinear effect from this instantaneous beam profile measurement.
|
|
|
||
| MOPLT070 | FFAG as Phase Rotator for the PRISM Project | injection, wiggler, vacuum, undulator | 713 | ||
|
A Fixed Field Alternating Gradient (FFAG) ring will be used as a phase rotator in the PRISM project. We report a design of the PRISM-FFAG in this paper. PRISM stands for "Phase Rotated Intense Slow Muon beam". It is a project to realize a super muon beam, which combines high-intensity, low-energy, narrow energy-spread and high purity. Its aimed intensity is about 1011-1012 muons per sec. The muon beam will be provided with a low kinetic energy of 20MeV to optimize for the stopped muon experiments. FFAG has some advantageous characteristics to achieve such superb beam. These are a large momentum (longitudinal) acceptance, a wide transverse acceptance with strong focusing, and synchrotron oscillation, which is needed to perform phase rotation. According to simulations, initial energy spread of 20MeV±40% is reduced down to ±6% after 5 turns of muons in the FFAG ring. In the FFAG ring almost all pions decay into muon, hence extracted beam has extremely low pion contamination. A program to construct the PRISM-FFAG ring has been started. It would be completed by the end of JFY 2005.
|
|
|
||
| MOPLT071 | EPICS Based Control System for the KOMAC RF System | injection, wiggler, vacuum, undulator | 716 | ||
|
This paper presents the RF control system for Korea Multi-purpose Accelerator Complex (KOMAC). KAERI (Korea Atomic Energy Research Institute) has been performing the project named KOMAC. As the 3nd phase of the project, 20MeV proton accelerating structure is under development. The new design is based on the use of VME based Multi-function modules connected to the specific low level RF Controllers(LLRF) via distributed I/O modules and Serial communication modules. The control system was based on EPICS (Experimental Physics and Industrial Control System) from the end of 2003. Installation and commissioning of the RF module is scheduled on 2004. Control system to integrated the RF System to the KOMAC control system is implemented. Hardware, software and various applications are developed to support the operation of RF Control system. This paper EPICS based control system for KOMAC RF
|
|
|
||
| MOPLT072 | Effects of Positrons on Relativistic Solitons in Laser-Plasma Interactions | injection, wiggler, vacuum, undulator | 719 | ||
|
An extended 1D kinetic model of relativistic solitons by high power lasers in three species plasmas is suggested and it is applied to analysis on the effects of electron-positron pairs on the solitons. Stability condition of the solitons is derived. The range of parameters for the stable solitons are specified in the frequency-temperature plane. With the creation of electron-positron pairs, relativistic solitons appear stable in wider range of frequencies and temperatures. The regions are expanded toward higher values in overall ranges in the frequency-temperature plane. The stability conditions are affected by the density of positrons. The variation of shapes, peak E-field, and width of the solitons by varying the positron density are analyzed. We discuss the implications of the variation in the soliton on the ion accelerations by it.
|
|
|
||
| MOPLT073 | Picosecond High Voltage Switching for Pulsed DC Acceleration | acceleration, laser, wiggler, vacuum | 722 | ||
|
Laser wakefield acceleration promises the production of high energy electrons from table-top accelerators. External injection of a (low energy) electron bunch into a laser wakefield requires acceleration gradients of the order GV/m. In principle DC acceleration can achieve GV/m acceleration gradients. If high voltage pulses of the order MV can be switched with picosecond precision, the performance of such an accelerator would be greatly enhanced and even multistage DC acceleration would become feasible. Presently risetime and jitter of high voltage pulses in high voltage laser triggered spark gaps are limited to the nanosecond regime by the initial stochastic breakdown process in the gap. A way to overcome this limitation is to create a line focus between the electrodes with an intensity above 1018 W/m2 using a high power femtosecond Ti:Sapphire laser. Because of the instantaneous ionization and high degree of ionization in the plasma channel, picosecond switching precision can be achieved and jitter is reduced significantly. A spark gap test setup with 3 mm interelectrode distance has been build and the first measurements have been done. Femtosecond diagnostics for characterization of the laser induced plasma and electro-optic diagnostics for the high voltage pulse have been developed.
|
|
|
||
| MOPLT075 | Ideal Waterbag Electron Bunches from an RF Photogun | laser, wiggler, acceleration, vacuum | 725 | ||
|
With the implementation of fs mode-locked Ti:Sapphire lasers in high-gradient RF photoguns, a new charged particle acceleration regime has emerged, the so-called pancake regime. Pancake bunches have by definition a restframe length which is much smaller than the bunch radius. This geometry allows a relatively simple, but effective analytical description of the space-charge dominated, critical initial part of the acceleration trajectory. In high-gradient RF photoguns the pancake regime can be relevant up to several MeV. The general opinion is that extremely short bunches should be avoided during the initial stages of the acceleration process, because high space charge densities are always detrimental to the final beam quality. We show that this is not necessarily true: shorter bunches may even lead to better beams.
|
|
|
||
| MOPLT078 | The Coupling Compensation and Measurement in the Interaction Region of BEPCII | laser, wiggler, acceleration, vacuum | 728 | ||
|
The detector solenoid field in the BEPCII interaction region will be compensated by 6 anti-solenoids, which are located nearby the interaction point. The coupling compensation scheme and the method to tune the x-y coupling at the interaction point will be introduced in detail.
|
|
|
||
| MOPLT081 | Low Energy Ion Beam Dynamics in Axisymmetric RF Undulator Linac | laser, wiggler, vacuum, resonance | 731 | ||
|
The ion beam focusing and acceleration in an axisymmetric periodic RF undulator structure is considered. There is suggested that RF field has no a synchronous wave and accelerating force is to be driven by a combination of two non-synchronous waves. The influence of non-synchronous harmonics on ion beam dynamics is studied by means of a smooth approximation. Choice and optimization of RF field harmonics are made to obtain maximal transmission coefficient. The result is verified by a numerical simulation. The comparison with a conventional RF linac, where a synchronous harmonic accelerates a beam and non-synchronous one is focusing a beam, is described. This comparison is suitable for demonstration of the capabilities of an undulator linac.
|
|
|
||
| MOPLT086 | Upgrading the Control System at KCSR | laser, wiggler, vacuum, resonance | 734 | ||
|
Till now Kurchatov Centre of Synchrotron Radiation facility control system is based on a CAMAC-oriented computers network. In this paper the project of upgrading and results of prototyping of the new equipment is submitted. Upgrading includes two levels. First, it is possible to create the modern CAMAC crate-controller, connected with standard network. More advanced variant will consist in replacement of CAMAC modules with the embedded controllers of equipment. Second level is a creation of a local managing network of personal computers, as consoles of the control system. The control system is functionally divided into four levels: 1) the controllers managing in a real-time mode by the executive equipment; 2) the workstations which are supporting the link with controllers by CAN-network; 3) the server of applications containing a dynamic database; 4) the PCs network for users applications. Examples of realisation of the software are presented.
|
|
|
||
| MOPLT087 | Research of Possibility to use Beam Polarization for Absolute Energy Calibration in High-precision Measurement of Tau Lepton Mass at VEPP-4M | laser, wiggler, vacuum, induction | 737 | ||
|
Experiments of 2002-2003 years on measurement of duration of beam polarization existence in VEPP-4M electron-positron storage ring after injection of polarized beams from VEPP-3 booster at energies in the vicinity of tau-lepton production threshold (1777 MeV) are described. Polarized beams in such conditions are planned to use in the experiment at VEPP-4M with KEDR detector on high precision measurement of tau-lepton mass wiyh the help of resonant depolarization technique for absolute calibration of particle energy. It was shown that despite of closeness of the strong depolarizing integer spin resonance (1763 MeV) the polarization lifetime though is limited, but still is sufficient for realization of energy calibration procedure with a high accuracy (10-6).
|
|
|
||
| MOPLT088 | Experimental Plasma Wake-field Acceleration Project at the VEPP-5 Injection Complex | plasma, laser, wiggler, acceleration | 740 | ||
|
The project of an experimental facility based on the VEPP-5 injection complex is described. Due to a good quality of electron or positron beams and special beam preparation system, the facility opens several possibilities for studies of the plasma wakefield acceleration: high peak beam currents, arbitrary beam profiles, long term beam-plasma interaction (up to the full driver depletion), and precise beam diagnostics. Various wakefield regimes can be experimentally demonstrated and studied: the efficient blow-out regime with a low energy spread and high acceleration rate (up to several GeV per meter); multibunch regime; long bunch instabilities; beam self-organization in plasma; plasma lens. If successfully realized, this experiment becomes a solid argument for feasibility of a high-energy collider based upon the plasma wakefield acceleration.
|
|
|
||
| MOPLT089 | SOS-diode Based Pulser for the Injection System of the Collider VEPP-2000 | plasma, laser, wiggler, acceleration | 743 | ||
|
We describe high voltage pulsers for supplying of kickers of the collider VEPP-2000 injection system. The high voltage pulse is formed as a result of a sharp break of a high current, accumulated previously in storage elements, by means SOS-diode. Pulse forming lines or inductances could be used as the storage elements. The generators form the quasi-rectangular pulses on the 50-Ohm load. The generator scheme is described also.
|
|
|
||
| MOPLT090 | High Pulse and Average Power Low-induction Load | plasma, laser, wiggler, acceleration | 746 | ||
|
A high pulse and average power low-induction load with a built-in divider is described in this report. The load has a nominal resistance of 25 Ohm and is designed to operate with a repetition rate of up to 50 Hz at a pulse duration (FWHM) of 100 ns, a rise/fall time of 50 ns and a pulse amplitude of up to 40 kV. In this mode the dissipated energy is equal to about 8 J per pulse and average power is up to 400 W. The load can be used as an absorbing load and as a block element in high-voltage engineering.
|
|
|
||
| MOPLT091 | Accelerator Physics Issues of the VEPP-4M at Low Energy | plasma, laser, wiggler, acceleration | 749 | ||
|
The VEPP-4M electron-positron collider is being prepared for a new high-energy physics run in the 1.5 - 2.0 GeV energy range. During the first run (2001-2002), precision mass measurements of the J/psi and psi' mesons using the KEDR detector have been carried out with a record accuracy. To provide high performance, efforts for investigation and further development of the machine have been done. The most important results are described. A record absolute accuracy of energy measurement was achieved using the resonant depolarization method. A possibility to use this method for the absolute energy calibration in tau-lepton mass measurements is studied. For the first time, the Moeller polarimeter based on an internal polarized gas jet target has been developed and successfully used at the VEPP-3 booster storage ring. A system of energy measurement using Compton back-scattering has been put into operation. To increase the machine luminosity, operation with dipole wigglers is studied, and a project of turn-by-turn feedback system to suppress beam instabilities has been started. For beam diagnostics, a multi-anode photomultiplier tube and a white light coronograph were installed. The VEPP-4M operation experience with the longitudinal magnetic field within the KEDR detector is also described.
|
|
|
||
| MOPLT092 | Single Mode RF Cavity for VEPP-2000 Storage Ring Based Collider | plasma, laser, wiggler, acceleration | 752 | ||
|
Accelerating cavity 172 MHz with strong damped higher-order modes (HOM) for VEPP-2000 electron-positron collider have been made in Novosibirsk. Resonance frequences and Q values of cavity HOMs are measured and analysed. Most of HOMs have Q values less than 300. We compare these results with computer calculations of HOM.
|
|
|