| Paper | Title | Page |
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| MOPD001 | Spin Dynamics Simulations At AGS | 666 |
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To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electro-magnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained. |
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| MOPD002 | Acceleration of Intermediate Charge State Heavy Ions in SIS18 | 669 |
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After partially completing the upgrade program of SIS18, the number of intermediate charge state heavy ions accelerated to the FAIR booster energy of 200 MeV/u, could be increased by a factor of 50. Meanwhile, more than 1010 Uranium ions with charge state 27+ have been accelerated with moderate beam loss by ionization and reasonably stable residual gas pressure conditions. The specific challenge for the SIS18 booster operation is the high cross section for ionization due to the low charge state in combination with gas desorption processes and the dynamic vacuum pressure. Especially for this operation mode which is requied to match the intensity requirements for FAIR, an extended upgrade program of SIS18 is presently ongoing and partially completed. The achieved progress in minimizing the ionization beam loss underlines that the chosen technical strategies described in this report are appropriate. |
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| MOPD003 | Engineering Status of SIS100 | 672 |
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The engineering design, including the specifications for the accelerator components of the FAIR synchrotron SIS100 has been summarized in the Technical Design Report. The final stage of technical planning shall approach production readiness for the major technical systems in 2010. Significant progress has been achieved in the design of the cryomagnetic system with its main dipole and quadrupole modules, enabling the production of the first pre-series dipole magnet. Slight modifications of the lattice have been implemented to equalize most of the cryostat interconnections, leading to a simplified design and installation effort, and a reduced variety of components and spar parts. The new parallel tunnel allows optimal short interconnections between the supply units and power converters and the accelerator components. The status of the engineering design of SIS100 will be reported. |
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| MOPD004 | Magnetic Field Correction in Normal Conducting Synchrotrons | 675 |
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While ramping the magnets in a synchrotron the magnetic fields deviate from their set values. Especially the field errors in dipole and quadrupole magnets result in different problems during operation. At the Heidelberg Ion Therapy Center HIT a measuring system with extremely high precision has been developed. It can measure in real time integral magnetic fields with a precision of better than 5*10-5 in a reproducible way. A feed-back control system for the magnetic fields is being installed and will be operational in May 2010. This control loop lets the magnets reach the nominal field much faster and thus shortens the dead time in a synchrotron cycle. The cycle can be reduced by 30% and more patients can be treated. |
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| MOPD005 | Design of PEFP RCS | 678 |
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As a feasible extension plan of the proton engineering frontier project (PEFP) 100-MeV proton linac, the conceptual design of an rapid cycling synchrotron (RCS) is under progress. The main purpose of the synchrotron is a spallation neutron source and it also includes the slow extraction option for basic and applied science research. In the initial stage, the beam power is 60 kW by using a scheme of 100-MeV injection and 1-GeV extraction. There is a scheme to increase power to 500 kW through a 3-stage upgrade. The injection and extraction energies will be 200-MeV and 2-GeV respectively after the final upgrade. This article summarizes the present status of the RCS design. It includes the physics design including injection and acceleration, and conceptual design of some magnets and RF cavity. |
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| MOPD007 | Design of the Nuclotron Booster in the NICA Project | 681 |
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The main goal of the Nuclotron booster construction are following: accumulation up to 4·10+9 Au32+ ions; acceleration of the ions up to energy of 600 MeV/u that is sufficient for stripping of the ions to the bare nucleus state; simplification of the requirements to the vacuum conditions in the Nuclotron; forming of the required beam emittance at the energy of 100 MeV/u with electron cooling system. The features of this booster, the requirement to the main synchrotron systems and their parameters are presented. |
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| MOPD008 | Status of the Nuclotron. 'Nuclotron-M' project | 684 |
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The 'Nuclotron-M' project started in 2007 is considered as the key point of the first stage of the NICA/MPD project. General goal of the 'Nuclotron-M' project is to prepare all the systems of the Nuclotron for its long and reliable operation as a part of the NICA collider injection chain. Additionally the project realization will increase the Nuclotron ability for realization of its current experimental program. Results of the last runs of the Nuclotron operation are presented. |
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| MOPD009 | Injector Complex of the NICA Facility | 687 |
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The injector complex of the NICA facility consists of existing Alvarez-type linac LU-20 and new heavy ion linac HILac. The LU-20 is under modernization now, the HILac will be constructed during coming years. Parameters of the accelerators are presented. |
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| MOPD010 | Lattice of the NICA Collider Rings | 690 |
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Main element of the NICA facility is the collider equipped with stochastic and electron cooling systems to provide experiment with heavy ions like Au, Pb or U at energy from 1 to 4.5 GeV/u with average luminosity of the level of 1027 cm-2 s-1. The possible lattices providing the required parameters are discussed. |
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| MOPD011 | Project of the Nuclotron-Based Ion Collider Facility (Nica) at JINR | 693 |
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The Nuclotron-based Ion Collider fAcility (NICA) is the new accelerator complex being constructed at JINR aimed to provide collider experiments with heavy ions up to uranium at the center of mass energy from 4 to 11 GeV/u. It includes 6 Mev/u linac, 600 MeV/u booster, upgraded SC synchrotron Nuclotron and collider consisting of two SC rings, which provide average luminosity of the level of 1027cm-2s-1. |
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| MOPD013 | Upgrade of the Quench Protection Systems for the Superconducting Circuits of the LHC Machine at CERN: From Concept and Design to the First Operational Experience | 696 |
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Two events, occurring in 2008 during commissioning of the LHC circuits, lead to fundamental changes to the scope of circuit protection. The discovery of aperture-symmetric quenches and the accidental rupture at 9kA of an interconnecting busbar resulted in an emergency program for development and implementation of new protection facilities. The new scheme comprises a distributed busbar supervision system with early warning capabilities based on high-precision splice resistance measurements and system interlocks for rapid de-excitation of the circuit in case of a sudden splice resistance increase. The developed symmetric quench detectors are digital systems with radiation-resistant FPGA logic controllers, having magnet heater firing capabilities. This program successfully allowed a safe re-powering of the collider. The concept of the new electronics boards and the powering modules will be described. More than 14'600 extra cables and 6'000 new detector and control cards were added to the existing QPS system. A first evaluation of the system performance as well as a number of interesting discoveries made during the commissioning will be presented. |
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| MOPD014 | Single-batch Filling of the CERN PS for LHC-type Beams | 699 |
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Since the CERN PS Booster cannot simultaneously provide the beam brightness and intensity required, the nominal (25ns bunch spacing) proton beam for the LHC involves double-batch filling of the PS machine. Linac 4, which is under construction, will eventually remove this restriction. In the meantime, the request for 50 and 75ns bunch spacings to mitigate electron cloud effects has lowered the intensity demand such that the Booster can meet this in a single batch without compromising beam brightness. Single-batch transfer means providing two bunches from each of three Booster rings and, in turn, that the bunch spacing is modified by the addition of an h=1 rf component to the h=2 in the Booster in order to fit the h=7 rf buckets waiting in the PS (whilst leaving one bucket empty for kicker purposes). Following the first experiments performed in 2008, the rf manipulations in the Booster have been refined and those in the PS have been modified to cope with single-batch beams. This latest work is presented for both the 50 and 75ns variants. |
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| MOPD015 | Status of the Linac4 Project at CERN | 702 |
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The construction of Linac4, a 160 MeV H- Linac, is the first step in upgrading the LHC injector chain. Unlike CERN's present injector linac, Linac4 will inject into the subsequent synchrotron via charge exchange injection. In a first stage, it will inject into the existing CERN PS Booster. At a later stage, Linac4 has the option to be extended by a superconducting linac (SPL) which could then inject into a new synchrotron (PS2). Construction of Linac4 has started in 2008, and beam operation is presently planned for 2014. An overview of the Linac4 main parameters and design choices is given, and the status of the construction reported. |
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| MOPD016 | Injection Upgrades for the ISIS Synchrotron | 705 |
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The ISIS Facility based at the Rutherford Appleton Laboratory in the UK is the world's most productive spallation neutron source. Presently it runs at beam powers of 0.2 MW, with RF upgrades in place to supply increased powers for the new Second Target Station. Increasing injection energy into the synchrotron beyond the existing 70 MeV level has significant potential to increase intensity as a result of reduced space charge. This paper outlines studies for this upgrade option, which include magnet and power supply upgrades to achieve a practical injection system, management of increased injection region activation levels due to higher energy un-stripped particles and ensuring the modified longitudinal and transverse beam dynamics during injection and acceleration are possible with low loss at higher intensity levels. |
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| MOPD017 | Impedance Considerations for the Design of the Vacuum System of the CERN PS2 Proton Synchrotron | 708 |
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In order for the LHC to reach an ultimate luminosity goal of 1035, CERN is considering upgrade options for the LHC injector chain, including a new 50 GeV synchrotron of about 1.3 km length for protons and heavy ions, to be called the PS2. In this ring the proton energy is ramped from 4 GeV in 1.2 s, and the design (proton) current is 2.7 A. The present baseline of the vacuum system considers elliptical stainless steel chambers bakeable up to 300°C, various coatings to mitigate electron cloud are under study. For a bare stainless steel or Inconel chamber, the resistive wall wake alone will lead to multi-bunch instability, whereas for transverse mode coupling (TMCI), the threshold is above the design beam current, though this instability may become an issue once other impedance contributions are taken into account. A copper layer of varying thickness is shown to raise the TMCI threshold but to have relatively little effect on the multi-bunch resistive-wall growth rate unless the coating is very thick. We are also studying the effect of the copper coating on the penetration of the guide field during the energy ramp, which sets an upper limit on the allowable thickness. |
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| MOPD018 | A New Life for High Voltage Electrostatic Accelerators | 711 |
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Air insulated Cockcroft-Walton (Grienacher) cascades have been historically used to generate high voltages for accelerating particles. This paper explores how this technology can be utilised through a system level approach to develop more compact accelerator configurations with much higher voltages and gradients. One such concept is presented that realises a 20MeV, 1mA tandem accelerator that has a footprint ~2m^2 |
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| MOPD019 | Tandem Accelerator as the Injector for the Medical-use Synchrotron at the Wakasa-wan Energy Research Center | 714 |
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We have operated the accelerator system which consists of a tandem accelerator and a synchrotron since the completion of the construction and beam commissioning at the Wakasa-wan Energy Research Center, Tsuruga, Japan in 2000. The acceleration voltage of the tandem accelerator amounts to 5 MV and is generated by the Dynamitron-type cascade voltage doubler rectifier. The beam from the tandem accelerator is transported to the MeV-ion experimental area for the irradiation to the industrial or biological material and for the ion beam analysis. The tandem beam is also injected to the 200 MeV proton synchrotron. The synchrotron beam has been used for the high energy irradiation and the cancer therapy. The tandem accelerator is used for a lot of purposes including cancer therapy, therefore, stable operation of the system and efficient sharing of the operation duration are required. Developments of the accelerator are presented putting a stress on the stable and efficient operation of the system in this paper. |
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| MOPD020 | Ion Injector Based on Tandem Accelerator | 717 |
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An electrostatic tandem accelerator with 1.25 MV at the high voltage terminal was designed, assembled and successfully commissioned at BINP. The accelerator of ELV-type will be used as injector for cancer therapy facility by carbon ions beams. The 10 keV beam of negative carbon ions with current up to 100 mkA is injected into the tandem and charge exchange in the vacuum heat insulation magnesium vapor target. The results of commissioning tests and beam parameters measurements are presented. |
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| MOPD021 | Low Energy Ion Injector at KACST | 720 |
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At the National Centre for Mathematics and Physics (NCMP), at the King Abdulaziz City for Science and Technology (KACST), Saudi Arabia, a versatile low energy ion injector has been developed in collaboration with the QUASAR group. This project will allow for a broad experimental program with most different kinds of ions both in single pass setups, but also with ions stored in a fixed-energy electrostatic storage ring. In this contribution, the design of the injector is presented. It was designed for beams with energies of up to 30 kV/q and will allow for switching between different ion sources from e.g. duoplasmatron to electrospray ion sources and to thus provide the users with a wide range of different beams. The mechanical construction of the injector is summarized and the status of its assembly at KACST presented. |
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| MOPD022 | Design of a Combined Fast and Slow Extraction for the Ultra-low Energy Storage Ring (USR) | 723 |
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The Ultra-Low energy Storage Ring (USR) within the future Facility for Low-energy Antiproton and Ion Research (FLAIR) will decelerate antiproton beams from 300 keV to energies of only 20 keV. Cooled beams will then be extracted and provided to external experiments. The large variety of planned experiments requires a highly flexible longitudinal time structure of the extracted bunches, ranging from ultra-short pulses in the nanosecond regime to quasi DC beams. This requires fast as well as slow extraction in order to cover whole range of envisaged beam parameters. A particular challenge was to combine elements for fast and slow extraction in one straight section of this electrostatic ring. In this contribution we present the results of beam dynamic simulations and describe the overall extraction scheme in detail. |
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| MOPD023 | DITANET - Investigations into Accelerator Beam Diagnostics | 726 |
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The Marie Curie Initial Training Network DITANET covers the development of advanced beam diagnostic methods for a wide range of existing or future accelerators, both for electrons and ions. The network brings together research centres like CERN or DESY, Universities, and private companies. DITANET currently has 27 partners from Europe and the USA and is committed to training young researchers in this field, performing cutting edge research in beam instrumentation, and exploiting synergies within this community. This contribution presents an overview of the research outcomes within the first two years of DITANET and summarizes the network's training activities. on behalf of the DITANET Consortium. |
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| MOPD024 | Scintillating Screen Studies for Low Energy, Low Intensity Beams | 729 |
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Future atomic and nuclear physics experiments put challenging demands on the required beam instrumentation. Low energy (<1 MeV), low intensity (<107 pps) beams will require highly sensitive monitors. This is especially true for the Facility for Low-energy Antiproton and Ion Research (FLAIR) where antiproton beams will be decelerated down to 20 keV and as few as 5·105 particles per second will be slowly extracted for external experiments. In order to investigate the limits of scintillating screens for beam profile monitoring in the low energy, low intensity regime a structured analysis of several screen materials, including CsI:Tl, YAG:Ce and scintillating fibre optic plate (SFOP), has been done under different irradiation conditions with keV proton beams. This contribution will present the experimental setup and summarize the results of this study. |
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| MOPD025 | Status of the SPIRAL 2 Superconducting LINAC | 732 |
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SPIRAL2 is a radioactive beams facility, composed of a superconducting linac driver, delivering deuterons with an energy up to 40 MeV (up to 5 mA) and heavy ions with an energy up to 14.5 MeV/u (up to 1 mA). The superconducting linac is composed of two families of quarter wave resonators: type A (optimized for beta=0.07, 1 per cryomodule) and B (beta=0.12, 2 per cryomodule). The accelerator is scheduled to be commissioned from mid-2011 onwards. The project is therefore in production phase. This paper summarizes the latest results and the status of the superconducting linac. All 16 type B cavities have been tested. Cryomodules from both families are presently being assembled in series. Installation of the cryomodules in the new building in GANIL shall begin in August 2011. |
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| MOPD026 | Unsegmented vs. Segmented 4-Vane RFQ: Theory and Cold Model Experiments | 735 |
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The RF design of a RFQ should satisfied several conditions, namely: voltage profile required by beam dynamics, a tunable structure, RF stability and reasonable sensitivity to possible perturbations induced by power operation. Voltage profile may be obtained either by a dedicated profiling of 2D cross-section and/or slug tuner adjustment. Tunability is directly related to spatial distribution of tuners. RF stability requires sufficient separation between accelerating quadrupole mode and (i) adjacent quadrupole modes, or (ii) adjacent dipole modes. Quadrupole modes separation is directly related to RFQ length, and can be increased if necessary via segmentation; position of dipole modes spectrum w.r.t. quadrupole spectrum may be adjusted using rod stabilizers inserted at RFQ ends and on either side of coupling circuits. We present a thorough comparison of these two options for a 6-meter long structure at 352 MHz, and show they both lead to a tunable structure. The design includes 3D electromagnetic simulation and application of transmission line to tuning. The sensitivity of both designs to perturbations is also evaluated. |
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| MOPD027 | The RF Design of the Linac4 RFQ | 738 |
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In the Linac 4 and the SPL, a 3 MeV RFQ is required to accelerate the H- beam from the ion source to the DTL input energy. While the 6-meter long IPHI RFQ was initially chosen for this application, a CERN study* suggested that a dedicated, shorter 3-meter RFQ might present several advantages. The 2D cross-section is optimized for lower power dissipation, while featuring simple geometrical shape suitable for easy machining. RF stability is evaluated using a 4-wire transmission model and 3D simulations, taking electrode modulation into account. The resulting RFQ is intrinsically stable and do not require rod stabilizers. End circuits are tuned with dedicated rods. RF power is fed via a ridged waveguide and a slot iris. Vacuum port assemblies are positioned prior to brazing to minimize RF perturbation. The 32 tuning slugs form a set of stable sampling, able to tune 9 modes. Tuner parameters are derived from bead-pull accuracy specification and fabrication tolerances. Signals delivered by pickup loops inserted in 16 of these tuners will be used to reconstruct the voltage profile under operation. Thermo-mechanical simulations are used to design temperature control specifications. |
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| MOPD028 | Commissioning of a New CW Radio Frequency Quadrupole at GSI | 741 |
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The super heavy element research is one of the outstanding projects at GSI. At SHIP* six new elements have been discovered; moreover, nuclear chemical experiments with transactinides were recently performed at TASCA**. This experimental program strongly benefits from high average beam intensities. In the past beam currents were raised significantly by a number of improvements. The present upgrade program comprises the installation of a superconducting (sc) 28 GHz ECR ion source, a new frontend (low energy beam transport and RFQ), and, in the long term, an sc cw Linac. For the short term, the new RFQ will raise the duty factor by a factor of two (50%), limited by the following accelerator only. This bottleneck will be resolved by the applied cw Linac. Beam tests with a newly developed sc CH cavity are scheduled for 2012. The setup of the RFQ as the major upgrade of the 20 year old HLI*** is in progress, the commissioning will be finished in March 2010. Besides a higher duty factor, improved longitudinal beam quality and transmission are expected. This paper reports on the challenging rf and beam commissioning. * Separator for Heavy Ion Reaction Products |
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| MOPD029 | Development of a new Broadband Accelerating System for the SIS18 Upgrade at GSI | 744 |
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This paper describes the development of a new rf accelerating cavity based on novel magnetic alloy materials (MA-materials) for operation at harmonic number h=2 (f=0,43- to 2,8 MHz) to provide the necessary accelerating voltage for SIS18 injector operation with high intensity heavy ion beams in a fast operation mode with three cycles per second. The acceleration system consist of three units which are able to operate independently from each other. That is important, since each ion for FAIR has to cross the h=2-rf-system and in the case of a damage a reduced operation has to be ensured. Since the cavities are filled with lossy MA-ring-cores, which are iron based Finemet FT3M ring cores from Hitachi, the cavities show a broadband behaviour and thus no cavity tuning during the acceleration ramp will be necessary. Due to the high saturation field strength of Finemet (1,2 T) the overall length of all three cavity units can be very short. This is an important feature since due to many insertions which were additionally inserted into the synchrotron ring SIS12/18 in the meantime, the available length in SIS12/18 for the cavity units is with 4 m very short. |
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| MOPD030 | The New CW RFQ Prototype | 747 |
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Abstract A short RFQ prototype was built for tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-Simulations with CST Microwave Studio and measurements were done. Conditioning of the facility with 20 kW/m and simulations of thermal effects with ALGOR are on focus now. First results and the status of the project will be presented. |
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| MOPD031 | Development And Measurements on a Coupled CH Proton Linac for FAIR | 750 |
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For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six coupled CH-cavities operated at 325 MHz. Each cavity will be powered by a 3 MW klystron. For the second acceleration unit from 11.7 to 24.3 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH-cavities. For this second tank technical and mechanical investigations have been done in 2009 to prepare a complete technical concept for manufacturing. Recently, the construction of the prototype has started. The main components of this second cavity will be ready for measurements in spring 2010. At that time the cavity will be tested with dummy stems (made from aluminum) wich will allow precise frequency and field tuning. This paper reports on the technical development and achievements during the last year. It will outline the main fabrication steps towards that novel type of proton DTL. |
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| MOPD032 | Superconducting CH-Cavity Development | 753 |
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At the Institute for Applied Physics a superconducting CH-Cavity (Crossbar H-Mode) has been developed. It is the first multi-cell drift tube cavity for the low and medium energy range of proton and ion linacs. A 19 cell, β = 0.1 prototype cavity has been fabricated and tested successfully with a voltage of 5.6 MV corresponding to gradients of 7 MV/m. The construction of a new superconducting 325 MHz 7-gap CH-cavity has started. This cavity has an optimized geometry with respect to tuning possibilities, high power RF coupling, minimized end cell lengths and options for surface preparation. Static tuning is carried out by small niobium cylinders on the girders. Dynamic tuning is performed by a slow bellow tuner driven by a step motor and a fast bellow tuner driven by a piezo. Additional thermal and mechanical simulations have been performed. It is planned to test the cavity with a 10 mA, 11.4 AMeV (β = 0.158) beam delivered by the Unilac at GSI. Another cavity (f = 217 MHz, β = 0.059) is currently under development for the cw Heavy Ion Linac at GSI. It is the first of nine sc CH-Cavities planned for this project covering an energy range from 1.4 to 7.3 AMeV. |
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| MOPD033 | Simulation for a Beam Matching Section with RFQSIM | 756 |
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The goal of the Frankfurt Funneling Experiment is to multiply beam currents by merging two low energy ion beams. In an ideal case this would be done without any emittance growth. Our setup consists of two ion sources, a Two-Beam-RFQ accelerator and a multi cell deflector which bends the beams to one common beam axis. The end section of the RFQ electrodes are designed to achieve a 3d focus at the crossing point of the two beam axis. New simulations with the RFQSIM-Code for a matching system with extended electrodes will be presented. |
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| MOPD034 | Beam measurements at the Frankfurt Funneling Experiment | 759 |
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Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with electrostatic lens systems, a Two-Beam-RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ. A funneling deflector combines the bunches to a common beam axis. Current work is beam tests with the new beam matching section. First funneling beam and energy measurements with the improved Two-Beam-RFQ will be presented. |
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| MOPD035 | Tuning of the 4-rod RFQ for MSU | 762 |
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A new reaccelerator facility ReA3 is currently under construction for National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). As part of that project a new 3.5 m long 4-rod Radio Frequency Quadrupole (RFQ) has been build. This RFQ accelerates ions with a Q/A ratio of 0.2 up to 0.5 from an input energy of 12 keV/u to the final energy of 600 keV/u. We have designed the 80.5 MHz-RFQ with a square cavity cross section. It was build and tuned in Frankfurt and has been delivered to MSU. The design and the tuning process of the ReA3-RFQ will be discribed in this paper. |
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| MOPD036 | Simulations of Buncher-cavities with Large Apertures | 765 |
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Buncher-cavities re-accelerate, bunch or re-bunch particle beams. A special form of these buncher-rf-cavities is a spiral-structure. Two different spiral resonators were simulated and build for the new EBIS LINAC at Brookhaven National Laboratory. These buncher-cavities have a remarkably large aperture of 100 mm. To optimize the cavities to the BNL-frequency of 100 MHz, simulations have been carried out. The impact of changing the gap width, drifttube-, and spiral arm-length on the design of the spiral cavities, has been analyzed. Results of simulations and measurement will be presented. |
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| MOPD037 | Recent Studies on a 3-17MeV DTL for EUROTRANS with Respect to RF Structures and Beam Dynamics | 768 |
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EUROTRANS is a EUROpean Research Programme for the TRANSmutation of High Level Nuclear Waste in an Accelerator-Driven System. Frankfurt University is responsible for the development of the 352MHz injector which mainly consists of a 3MeV RFQ and a 3-17MeV CH-DTL. Based on the beam dynamics design, the CH-cavities were designed with the concern to optimize the RF properties. In the cavity design, the tube-gap configurations were modified, so the beam dynamics has been adjusted to fit the new effective gap voltage profiles accordingly. A comparison of the beam dynamics results before and after the RF optimization is presented. |
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| MOPD040 | Secondary Particles in the Acceleration Stage of High Current, High Voltage Neutral Beam Injectors: the Case of the Injectors of the Thermonuclear Fusion Experiment ITER | 771 |
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The thermonuclear fusion experiment ITER, requires 33 MW of auxiliary heating power from two Neutral Beam Injectors (NBI), each of them providing 40 A of negative deuterium ions. The EU activities oriented to the realisation of the electrostatic accelerator comprise the construction in Padova of SPIDER, a facility devoted to the optimisation of the beam source. SPIDER parameters are: 100 keV acceleration, 40/60 A (deuterium/hydrogen) current. For the optimised SPIDER accelerator the present contribution provides a characterisation of secondary particles, which include electrons produced by impact of ions on grid surfaces, stripped from negative ions inside the accelerator, and produced by ionisation of the background gas, and the corresponding positive ions. Currents and heat deposited on the various grids and spatial distribution by secondaries will be described. It is found that most of the heat loads on the accelerator grids is due to electrons; moreover the features of secondaries exiting the accelerator and back-streaming towards the source will be presented. The results will be compared with old investigations concerning the NBI 1 MeV accelerator. |
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| MOPD041 | Recent Progress in the Beam Commissioning of J-PARC Linac | 774 |
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The user operation of J-PARC linac was started in December 2008, and it has been operated with the limited beam power of less than 1.2 kW making efforts at improving hardware availability. Since November 2007, the beam power from the linac has been increased to 7.2 kW that corresponds to 120 kW from the downstream 3-GeV synchrotron. We also performed a high-power demonstration run with 18 kW (or 300 kW from the synchrotron) that corresponds to the design beam power for the present configuration. In the course of the beam power ramp-up, we have suffered from significant beam losses in the beam transport line after the linac. Accordingly, the emphasis of the beam tuning has been shifted to the mitigation of the uncontrolled beam losses. Some of the loss mechanisms are identified in the beam studies, and we have succeeded in mitigating them. In this paper, we present recent progress in the beam commissioning of J-PARC linac with emphasis on the effort to mitigate the beam losses. |
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| MOPD042 | Commissionning of the IFMIF/EVEDA Accelerator Prototype – Objectives & Plans | 777 |
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In the frame of the IFMIF/EVEDA project, a high-intensity (125 mA) CW deuteron accelerator will be installed and commissioned at the Rokkasho's Broader Approach (BA) site. The main objective of this 9 MeV prototype is to provide information on the feasibility of the design, the manufacturing and the operation of the two linacs (up to 40 MeV) foreseen for IFMIF*. Based on the requirements for each System (Accelerators, Lithium target and Tests Facility) which are deduced from the IFMIF fusion material irradiation requirements, given by the users, the objectives of this accelerator prototype are defined and presented here. Also, because of the distributed nature of the design work and the procurement of the accelerator, organization of the installation and commissioning phase is essential. The installation and commissioning schemes, the organization proposed and the overall plans are presented. *IFMIF International Team, IFMIF Comprehensive Design Report (CDR) 2003. |
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| MOPD043 | Thermal Characteristics of a New RFQ for J-PARC | 780 |
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A new RFQ for the J-PARC linac is under construction for more stable operation. The requirement of this RFQ is almost same as the now-operating one; the resonant frequency is 324MHz, the injection energy is 50 keV, the extraction energy is 3 MeV, peak beam current is 30 mA, and RF duty is 1.5%. The resonant frequency tuning during operation will be done by adjusting the temperatures of the cooling waters. In this paper, thermal characteristics of this RFQ and control system of the cooling water temperature is described. |
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| MOPD044 | Fabrication of the New RFQ for the J-PARC Linac | 783 |
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The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a negative hydrogen beam from 0.05MeV to 3MeV toward the following DTL. As the trip rates of the practically using RFQ increased in autumn 2008, we started the preparation of a new RFQ as a backup machine. The beam dynamics design of the new RFQ is the same as the current cavity, however, the engineering and RF designs are changed. The processes of the vane machining and the surface treatments have been carefully considered to reduce the discharge problem. The vacuum brazing technique has been chosen for vane integration. In this report, the detailed design will be described with the progress of the fabrication of the new RFQ. |
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| MOPD045 | Design and Simulation of C6+ Hybrid Single Cavity Linac for Cancer Therapy | 786 |
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A new type Linac, HSC (hybrid single cavity) linac for cancer therapy, which configuration combines RFQ (Radio Frequency Quadrupole) accelerating structure and DT (Drift Tube) accelerating structure is being finished designs and simulations now. This HSC linac design had adopted advanced power-efficiency-conformation, IH (Interdigital H) structure, which acceleration efficiency is extremely high in the low-middle energy region, and had also adopted most advanced computer simulation technology to evaluate cavity electromagnetic distribution. The study purposes of this HSC linac focus to design of injector linac for synchrotron of cancer radiotherapy facilities. Here, this HSC linac has an amazing space effect because of compact size by coupled complex acceleration electrode and integrated the peripheral device which is made operation easy to handle. |
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| MOPD046 | Construction of New Injector Linac for RI Beam Factory at RIKEN Nishina Center | 789 |
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A new additional injector (RILAC2) is constructed at RIKEN Nishina Center in order to enable the independent operation of the RIBF experiments and super-heavy element synthesis. The RILAC2 consists of a 28 GHz superconducting ECR ion source, a low-energy beam transport with a pre-buncher, a four-rod RFQ linac, a rebuncher, three DTL tanks, and strong Q-magnets between the rf resonators for the transverse focusing. Very heavy ions with m/q of 7 such as 136Xe20+ and 238U35+ will be accelerated up to the energy of 680 keV/u in the cw mode and be injected to the RIKEN Ring Cyclotron without charge stripping. The RFQ linac, the last tank of the DTL, and the bunchers have been converted from old ones in order to save the cost. Construction of the RILAC2 started at the end of the fiscal 2008. The RFQ and DTLs will be installed in the AVF cyclotron vault and be tested in March 2010. The ECR ion source and low-energy beam transport will be set on the RILAC2 in 2010 summer, and the first beam will be accelerated in 2010 autumn. We will present the details of the linac part of RILAC2 as well as the progress of construction which includes the result of high power test of resonators. |
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| MOPD047 | Design of the CPHS RFQ Linac at Tsinghua University | 792 |
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The design progress of the Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University is presented in this paper. The RFQ will accelerate protons from 50 keV to 3 MeV, with the RF frequency of 325 MHz. The objective is to obtain the optimum structure of the RFQ accelerator with high transmission rate and tolerable total length. The beam dynamics are studied by the simulation of the proton beam in the RFQ accelerator with the code of PARMTEQM. The output proton beam from the RFQ is well matched into the DTL without Medium-Energy-Beam-Transport (MEBT) between the RFQ and DTL. * K.R. Crandall et al., RFQ Design Codes, LA-UR-96-1836. |
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| MOPD048 | Primary Design of DTL for CPHS | 795 |
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The Compact Pulsed Hadron Source (CPHS) has launched at Tsinghua University to develop a university neutron source based on a 13 MeV, 50 mA proton linac which consists of ECR ion source, LEBT, RFQ and DTL. The primary design of the DTL for the CPHS is presented in this paper, which includes the dynamics calculation, RF field optimization and error analysis. This DTL can accelerate 50 mA proton beam from 3MeV to 13 MeV with 1.2 MW RF power input. The DTL is directly connected after RFQ without Medium-Energy Beam-Transport line (MEBT). PMQs are adopted in drift tubes focusing. The magnetic field gradient of PMQs are programmed to match the transverse restoring forces at the end of the RFQ to avoid missmatch and avoid parametric resonances. |
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| MOPD050 | Operation of the PEFP 20MeV Proton Linac at KAERI | 798 |
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The 20MeV proton accelerator has been operating since 2007 when it got an operational license at Korea Atomic Energy Research Institute (KAERI) by Proton Engineering Frontier Project (PEFP). Beam property such as an emittnace was measured at the low energy beam transport (LEBT) to characterize the beam into the RFQ. In addition, several parts were modified to test the adaptability of those which would be used for the 100MeV linac. The modulator for the 100MeV linac was installed and tested in the 20MeV linac test bench. In addition, low level RF (LLRF) system was modified in the overall configuration and the operator interface (OPI) with EPICS. In this paper, the beam property measurement results and modification of the linac are presented. |
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| MOPD052 | Progress Work on High-current Heavy Ion Linac for ITEP TWAC Facility | 801 |
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The new heavy ion high current injector for ITEP-TWAC Facility is now under construction at ITEP for acceleration of ions with 1/3 charge to mass ratio up to energy of 7 MeV/u and beam current of 100 mA. The 81.5 MHz RFQ section based on 4 vane resonator with magnetic coupling windows is constructed for the beam energy of 1.566 MeV/u. The RF tuning of RFQ section has been presently completed and basically confirms the expected parameters calculated by 3D OPERA codes. The windows improve both azimuthal and longitudinal stabilization of the operating mode by increasing the separation from parasitic modes. The second section of 163 MHz H-type resonator is designed and in progress for construction. Status of machine construction activity and beam dynamics calculation are presented. |
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| MOPD053 | Conceptual Design of the ESS LINAC | 804 |
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A three year design update for the European Spallation Source (ESS) linac is just starting and a full review of this work will be presented. The acceleration in the medium energy part of the LINAC using the spoke cavities have been optimized and the rest of the machine has been redesigned to incorporate this optimization. The ESS LINAC will deliver an average power of 5~MW to the target in the nominal design and the possibility to upgrade to 7.5~MW has been included in all the design steps. Acknowledgments to all the people in the ESS LINAC Reference Group. |
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| MOPD054 | Mechanical Design, Brazing and Assembly Procedures of the Linac4 RFQ | 807 |
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The Linac4 RFQ will accelerate the H- beam from the ion source to the energy of 3 MeV. The RFQ is composed of three sections of 1 meter each, assembled by means of ultra high vacuum flanges and an adjustable centering ring. The complete 3-m long RFQ will be supported isostatically over 3 points like a simple beam in order to minimise the maximum deflection. The ridge line, used to feed the RF power into the RFQ, will be supported via springs and its position adjusted in such way that no strain is introduced into the RFQ at the moment of its connection. The mechanical design has been done at CERN where the modules are completely manufactured, heat treated and brazed also. In that way, all of the processes are carefully controlled and the influence, notably of the heat treatments, has been understood in a better way. Since 2002 several four vanes RFQ modules have been brazed at CERN for the TRASCO and IPHI projects. A two-step brazing procedure has been tested. This technique is actually used for the assembly of the CERN Linac4 RFQ. This paper describes the design, the mechanical procedures adopted for machining and assembly and the first results obtained. |
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| MOPD056 | The Mechanical Engineering Design of the FETS RFQ | 810 |
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This paper will present the mechanical engineering design for a 324 MHz 4-vane RFQ, which has been developed for the Front End Test Stand (FETS) project based at the Rutherford Appleton Laboratory (RAL) in the UK. The design criteria will be discussed along with particular design features of the RFQ including the tuners, vacuum ports, main body cooling pocket design and the support / alignment structure. Different techniques for creating the RF and vacuum seal between major and minor vanes are also discussed. |
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| MOPD057 | Assessing the Transmission of the H- Ion Beam on the Front End Test Stand | 813 |
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The front end test stand (FETS) [1] is entering the next stage of construction and commissioning, with the three-solenoid magnetic low energy beam transport (LEBT) line being installed. A thorough characterization of the beam leaving the Penning H- ion source has been performed. This includes measurements of the beam current using toroids and of the transverse emittance using slit-slit scanners. These measurements are performed over a wide range of source discharge and extraction parameters in order to understand how the transmission may be improved. Comments on the quality of the beam to be injected into the FETS radio frequency quadrupole (RFQ) are given. |
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| MOPD058 | Combined Electromagnetic-Thermal-Structural Simulation of the Four-metre Radio Frequency Quadrupole to be Installed on the Front End Test Stand | 816 |
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The front end test stand (FETS) [1] being constructed at the Rutherford Appleton Laboratory is entering the next stage of commissioning, with the three-solenoid magnetic low energy beam transport (LEBT) now installed and undergoing commissioning. The next major component to be manufactured is the 3 MeV, 324 MHz, four metre radio frequency quadrupole (RFQ). The mechanical design is almost complete so a comprehensive finite element model of the entire RFQ has been made in ANSYS to ensure the electromagnetic, thermal and structural properties are sound. An analysis of the cooling strategy and expected resonant frequency shift due to thermal expansion are presented. |
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| MOPD059 | MEBT Design for the RAL Front End Test Stand | 819 |
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The Medium Energy Beam Transport (MEBT) line for the Front End Test Stand (FETS) at RAL will transport a 60 mA, 2ms, 50 pps H- beam at 3 MeV. It uses a number of quadrupoles, re-bunching cavities and a fast-slow chopping system. In this paper we present the underlying MEBT design philosophy, beam dynamics simulations and implementation details. |
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| MOPD060 | Design Optimisation and Particle Tracking Simulations for PAMELA Injector RFQ | 822 |
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The PAMELA (Particle Accelerator for MEdicaL Applications) project aims to design an ns-FFAG accelerator for cancer therapy using protons and carbon ions. For the injection system for carbon ions, an RFQ is one option for the first stage of acceleration. Our integrated RFQ design process* has been developed further using Comsol Multiphysics for electric field modelling. The design parameters for the RFQ are automatically converted to a CAD model using Autodesk Inventor, and the electric field map for this model is simulated in Comsol. Particles can then be tracked through this field map using Pulsar Physics' General Particle Tracer (GPT). Our software uses Visual Basic for Applications and MATLAB to automate this process and allow for optimisation of the RFQ design parameters based on particle dynamical considerations. Possible designs for the PAMELA RFQ, including super-conducting and normal-conducting solutions, will be presented and discussed, together with results of the field map simulations and particle tracking for these designs. * M J Easton et al., RFQ Design Optimisation for PAMELA Injector, PAC09, Vancouver, Canada, April 2009, FR5REP066. |
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| MOPD061 | 650 MHz Option for High-energy Part of the Project X linac | 825 |
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650 MHz option for the high energy part of the 2.6 GeV, CW Project X linac is discussed. It may give significant benefits compared to current 1.3 GHz option based on the utilization of ILC-type beta=1 cavities. Results of the break point optimization for linac stages, cavity optimization and beam dynamics optimization are presented. Possible reduction in the number of cryomodules and linac length compared to the current linac project version is discussed. Cryogenic losses are analyzed also. |
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| MOPD062 | H-Mode Accelerating Structures with PMQ Focusing for Low-Beta Ion Beams | 828 |
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We are developing high-efficiency normal-conducting RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. Such IH-PMQ accelerating structures following a short RFQ can be used in the front end of ion linacs or in stand-alone applications, e.g. a compact deuteron-beam accelerator up to the energy of several MeV. Results of combined 3-D modeling for a full IH-PMQ accelerator tank ' electromagnetic computations, beam-dynamics simulations with high currents, and thermal-stress analysis ' are presented. The accelerating field profile in the tank is tuned to provide the best beam propagation using coupled iterations of electromagnetic and beam-dynamics modeling. A cold model of the IH-PMQ tank is being manufactured. |
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| MOPD063 | Experimental Study of the SNS MEBT Chopper Performance | 831 |
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The chopper system for the Spallation Neutron Source (SNS) provides a gap in the beam for clean extraction from the accumulator ring. It consists of a pre-chopper in the low energy beam transport and a faster chopper in the medium energy beam transport (MEBT). It took several iterations to develop a working design with the required parameters. In this paper we describe the latest design of the MEBT chopper deflector and give results of the experimental verification of the chopper effectiveness, the gap cleanness and the rise time measured with high resolution using the SNS laser wire. The effect on the losses will be discussed as well. |
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| MOPD064 | Bunched Beam Stochastic Cooling at COSY | 834 |
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The stochastic cooling is employed to reduce the momentum spread of accelerated 2 GeV proton beam at COSY. In addition the barrier voltages are successfully used to compensate the mean energy loss of the beam due to the thick internal target such as pellet target. To analyze the experimental results at COSY, we have developed the particle tracking code which simulate the particle behavior under the influences of stochastic cooling force, Schottky diffusion, thermal diffusion and IBS effects. The synchrotron motion due to the RF fields are included with 4th order symplectic way. The simulation results are well in agreement with the observed cooling process for the case of barrier voltage as well as RF field of harmonic number=1. In the present paper, the systematic analysis of the experimental results with use of the developed tracking codes are described. In addition the process of short bunch formation at the heavy ion collider at NICA project is investigated with use of the stochastic cooling. In that case the strong IBS effects are main limiting factor of making and keeping the short bunch as well as the space charge effects. Details of the simulation study will be presented. |
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| MOPD065 | Beam Accumulation with Barrier Voltage and Stochastic Cooling | 837 |
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Anti-proton beam accumulation at CERN and FNAL has been performed with use of stochastic stacking in the momentum space. Thus accumulated beam has a large momentum spread and resultantly large radial beam size with large dispersion ring. In the present proposed scenario, beams from the pre-cooling ring are injected into the longitudinal empty space prepared by the barrier voltages and subsequently the stochastic cooling is applied. After the well cooling, barrier voltages will prepare again the empty space for the next beam injection. We have simulated the stacking process up to 100 stacking with use of the bunched beam tracking code including the stochastic cooling force and the diffusion force such as Schottky diffusion term, thermal diffusion, IBS effects. The synchrotron motion by barrier voltages are included with 4th order symplectic method. Examples of the application to 3 GeV anti-proton beam for the HESR ring in FAIR project are presented as well as the accumulation of heavy ion beam 3.5 GeV/u Au, at the NICA collider at JINR project. |
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| MOPD066 | A Novel Method for the Preparation of Cooled Rare Isotope Beams | 840 |
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The ESR storage ring at GSI is operated with a wide range of heavy ions. In addition to stable heavy ions also rare isotope beams are studied in various experiments. A novel method to provide one- or few-component cooled fragment beams has been demonstrated experimentally. This technique uses a primary high energy heavy ion beam (several hundred MeV/u) bombarding a thick target in front of the storage ring. The reaction products are first separated by the magnetic structure of the storage ring. After storage of isotopes in a rigidity window of typically ± 2 per mille the isotopes are cooled to the same velocity by electron cooling. The cooled ions are circulating on different orbits according to their mass and charge. The momentum spread of the individual components is on the order 0.01 per mille or smaller depending on the intensity. The different components are radially well separated in regions with large dispersion. By the use of mechanical scrapers beam components in a certain radial region, corresponding to a range in masses and charges, can be selected, This way the stored rare isotope beam is curtailed to the components of choice. |
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| MOPD067 | Status of the 2 MeV Electron Cooler for COSY/ HESR | 843 |
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The 2 MeV electron cooling system for COSY-Jülich was proposed to further boost the luminosity even in presence of strong heating effects of high-density internal targets. The project is funded since mid 2009. Manufacturing of the cooler components has already begun. The space required for the 2 MeV cooler is being made available in the COSY ring. The design and construction of the cooler is accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The 2 MeV cooler is also well suited in the start up phase of the High Energy Storage Ring (HESR) at FAIR in Darmstadt. It can be used for beam cooling at injection energy and is intended to test new features of the high energy electron cooler for HESR. Two new prototypes of the modular high voltage system were developed, one consisting of gas turbines the other based on inductance-coupled cascade generators. The new 2 MeV electron cooler is described in detail and tests of components are reported. |
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| MOPD068 | Stochastic Momentum Cooling Experiments with a Barrier Bucket Cavity and Internal Targets at COSY-Jülich in Preparation for HESR at FAIR | 846 |
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Numerical studies of longitudinal filter and time-of-flight (TOF) cooling suggest that the strong mean energy loss due to an internal Pellet target in the High Energy Storage Ring (HESR) at the FAIR facility can be compensated by cooling and operation of a barrier bucket (BB) cavity. In this contribution detailed experiments at COSY to compensate the mean energy loss are presented. The internal Pellet target was similar to that being used by the PANDA experiment at the HESR. A BB cavity was operated and either TOF or filter stochastic momentum cooling was applied to cool a proton beam. Experimental comparisons between the filter and TOF cooling method are discussed. Measurements to determine the mean energy loss which is used in the simulation codes are outlined. The experiments proved that the mean energy loss can be compensated with a BB cavity. Results are compared with numerical tracking simulations which include the synchrotron motion in a barrier bucket as well as in an h = 1 cavity and stochastic momentum cooling. A detailed discussion of the tracking simulation code will be outlined in a separate contribution to this conference. |
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| MOPD069 | Ionization Cooling in a Low-energy ion Ring with Internal Target for Beta-beams Production | 849 |
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A compact ring with an internal target for the production of Li-8 or B-8 as neutrino or antineutrino emitters has been proposed*, to enhance the flux of radioactive isotopes for a beta-beam facility. The circulating beam is expected to survive for thousands of turns and, according to this scheme, the ionization cooling provided by the target itself and a suitable RF system will be enough to keep the beam transverse and longitudinal emittances under control. The ionization cooling potential for a preliminary ring design is here investigated by means of tracking simulations and analytical considerations, keeping in mind that a correct modeling of the beam-target interactions is fundamental for these studies. Technological issues for such a ring and possible show-stoppers are also briefly discussed. * C.Rubbia et al, NIM-A 2006.. |
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| MOPD070 | Numerical Study on Simultaneous Use of Stochastic Cooling and Electron Cooling with Internal Target at COSY | 852 |
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A small momentum spread of proton beam has to be realized and kept in a storage ring during an experiment with a dense internal target such as a pellet target. A stochastic cooling alone does not compensate the mean energy loss by the internal target. Barrier bucket operation will cooperate effectively the energy loss. In addition, the further small momentum spread can be realized with use of an electron cooling. In the present study, the simulation results on the simultaneous use of stochastic cooling and electron cooling at COSY are presented. |
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| MOPD071 | Horizontal-Vertical Coupling for Three Dimensional Laser Cooling* | 855 |
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In order to achieve three dimensional crystal beam, laser cooling forces are required not only in the longitudinal direction, but also in the transverse directions. With the resonance coupling method*, transverse temperature is transmitted into longitudinal direction, and we have already demonstrated horizontal laser cooling experimentally **. In the present paper, we describe an approach to extend this result to three dimensional cooling. The vertical cooling requires that the horizontal oscillation couples with the vertical oscillation. For achieving horizontal-vertical coupling, a solenoid in electron beam cooling apparatus is utilized with an experiment (Qx=2.07,Qy=1.07). For various solenoidal magnetic fields from 0 to 40Gauss, horizontal and vertical betatron tunes are measured by beam transfer function. For a certain region of the solenoidal magnetic field, these tunes are mixed up each other. By optimization of such a coupling, we aim to proceed to three dimensional laser cooling. * H. Okamoto Phys. Rev. E 50, 4982 (1994) |
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| MOPD072 | Optical Measurement of Transverse Laser Cooling with Synchro-Betatron Coupling* | 858 |
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Experiments of transverse laser cooling for 24Mg+ beam have been performed at the small ion storage and cooler ring, S-LSR. It is predicted that the longitudinal cooling force is transmitted to the horizontal direction with synchro-betatron coupling at the resonant condition*. The laser system consists of a 532nm pumping laser, a ring dye laser with variable wavelength around 560nm, and a frequency doubler. The horizontal beam size and the longitudinal momentum spread were optically measured by a CCD and a PAT (Post Acceleration Tube) respectively**, ***. The CCD measures the beam size by observing spontaneous emission from the beam and records in sequence of 100ms time windows the development of the beam profile. The time variation of the beam size after beam injection indicates the transverse cooling time. The initial horizontal beam size, which was about 1mm, was decreased by 0.13mm in 1.5s. The longitudinal momentum spread measured by PAT is increased at the resonant condition. This suggests transverse temperature was transferred to longitudinal direction by synchro-betatron coupling. Both measurements denote the horizontal cooling occurred only in the resonant condition ****. * H. Okamoto, Phys. Rev. {E50}, 4982 (1994) |
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| MOPD073 | Transverse Laser Cooling by Synchro-betatron Coupling | 861 |
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Transverse laser cooling with the use of a synchro-betatron coupling is experimentally demonstrated at the ion storage/cooler ring S-LSR. Bunched 40keV 24Mg+ beams are cooled by a co-propagating laser with a wavelength of 280nm. Synchrotron oscillation and horizontal betatron oscillation are coupled by an RF drifttube at a finite dispersive section (D = 1.1m) in order to transmit longitudinal cooling force to the horizontal degree of freedom*. Time evolution of horizontal beam size during laser cooling was measured by a CCD camera**. Horizontal beam sizes were reduced by 0.13mm within 1.5s after injection when the tune values satisfy a difference resonance condition, νs - νh = integer, at the operating tunes of (νh, νv, νs)=(2.067, 1.104, 0.067) and (2.058, 1.101, 0.058). Without resonance condition, the size reduction was negligibly small. The momentum spread was 1.7x10-4 on the resonance otherwise 1.2x10-4. These results show that the horizontal heats are transferred to the longitudinal direction through the synchro-betatron coupling with the resonance condition and are cooled down by a usual longitudinal bunched beam laser cooling. * H. Okamoto, Phys. Rev. E 50, 4982 (1994). |
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| MOPD074 | Beam Lifetime with the Vacuum System in S-LSR | 864 |
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S-LSR is a compact ion storage and cooler ring to inject beam of the 7MeV proton and the 40MeV Mg+. The average vacuum pressure measured by the vacuum gauges without beam was achieved up to about 4x10-9 Pa in 2007. Many experiments have been carried out using the proton and Mg beam, for example the one-dimensional beam ordering of protons utilizing the electron cooler, the extraction tests of the short bunched beam and the laser cooling for the Mg beam had been performed. The beam lifetime can be estimated with the vacuum pressure or the loss-rate of the beam energy. The values of the estimated lifetime are nearly equal to the measured lifetime values. The present status of the proton beam lifetime and the vacuum pressure is reported. |
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| MOPD075 | Effect of Secondary Ions on the Electron Beam Optics in the Recycler Electron Cooler | 867 |
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AAntiprotons in Fermilab's Recycler ring are cooled by a 4.3 MeV, 0.1 ' 0.5 A DC electron beam (as well as by a stochastic cooling system). The unique combination of the relativistic energy (γ = 9.49), an Ampere - range DC beam, and a relatively weak focusing makes the cooling efficiency particularly sensitive to ion neutralization. A capability to clear ions was recently implemented by way of interrupting the electron beam for 1-30 μs with a repetition rate of up to 40 Hz. The cooling properties of the electron beam were analyzed with drag rate measurements and showed that accumulated ions significantly affect the beam optics. For a beam current of 0.3 A, the longitudinal cooling rate was increased by factor of ~2 when ions were removed. |
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| MOPD076 | A Helical Cooling Channel System for Muon Colliders | 870 |
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Fast muon beam six dimensional (6D) phase space cooling is essential for muon colliders. The Helical Cooling Channel (HCC) uses hydrogen-pressurized RF cavities imbedded in a magnet system with solenoid, helical dipole, and helical quadrupole components that provide the continuous dispersion needed for emittance exchange and effective 6d beam cooling. A series of HCC segments, each with sequentially smaller aperture, higher magnetic field, and higher RF frequency to match the beam size as it is cooled, has been optimized by numerical simulation to achieve a factor of 105 emittance reduction in a 300 m long channel with only a 40% loss of beam. Conceptual designs of the hardware required for this HCC system and the status of the RF studies and HTS helical solenoid magnet prototypes are described. |
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| MOPD077 | Progress on Analytical Modeling of Coherent Electron Cooling | 873 |
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We report recent progresses on analytical studies of Coherent Electron Cooling. The phase space electron beam distribution obtained from the 1D FEL amplifier is applied to an infinite electron plasma model and the electron density evolution inside the kicker is derived. We also investigate the velocity modulation in the modulator and obtain a closed form solution for the current density evolution for infinite homogeneous electron plasma. |
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| MOPD078 | Large Aperture Electron Beam Scan with Vibrating Wire Monitor in Air | 876 |
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The Vibrating Wire Monitor (VWM) with aperture 20 mm was developed for scan of electron beam with large transversal sizes. Test experiments with VWM placed in air were done on the 20 MeV electron beam of Yerevan Synchrotron Injector with 4-7 uA at outlet. A new design of VWM is proposed for scan of the beam with even greater transversal sizes. |
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| MOPD079 | A Novel Synchrotron Radiation Interferometer for the Australian Synchrotron | 879 |
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A new arrangement for the synchrotron radiation interferometer was proposed - as far as is known, it is unique in the world. The Young's-type interferometer is composed of two independent and optically identical paths, each with a single slit on a motorised translating stage. These two single slit patterns are interfered to produce a double slit diffraction pattern. This arrangement permits rapid scanning of the profile of fringe visibility as a function of slit separation. The interferometer was used on two beamlines at the Australian Synchrotron, the optical diagnostic and infrared beamlines. The interferometer was used to measure the coherence of the photon beam created by the electron beam source, for normal and low emittance couplings. A large change in fringe visibility was observed, proving the experimental arrangement. The interferometer was validated in the measurement of the width of a hard-edged single slit, akin to Thompson and Wolf's diffractometer. Optical simulations and measurements inform proposed modifications to the optical diagnostic beamline, so as to implement the interferometer as a regular diagnostic tool. |
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| MOPD080 | Upgrade of the Booster Beam Position Monitors at the Australian Synchrotron | 882 |
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Thirty two Bergoz Beam Position Monitors are located in the Australian Synchrotron booster ring. They currently suffer from a poor signal-to-noise ratio and a low sample rate data acquisition (DAQ) system, provided by a portable DAQ device. This architecture is being upgraded to offer better performance. Phase matched low attenuation cables are being pulled and readout electronics will be located in two sites to reduce cable length. Data acquisition will be upgraded using a high accuracy PCI DAQ board. The board's trigger, originally delivered by a Delay Generator, will be generated by an Event Receiver output following our recent upgrade of the timing system. The new Linux driver will be EPICS-based, for consistency with our control system. |
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| MOPD081 | Progress with Low Intensity Diagnostics at ISAC | 885 |
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The ISAC accelerators presently deliver various stable and radioactive CW heavy ion beams to experiments with energies ranging from 2keV/u up to about 4.5 MeV/u ( for A/q = 6 ). Beam intensities also vary enormously being as low as a few hundred ions per second for certain radioactive ion species and as high as 100 enA for stable and pilot beams. Monitoring of beams with currents of less than ~0.5 epA requires a dedicated diagnostics instrumentation which typically makes use of radiation hard single particle detectors. Several such devices have been built and are under development at TRIUMF. Electron multiplier based SEEM monitors, solid state and scintillator detectors with a count rate capability in excess of 106 pps are employed. Device controls are integrated into the EPICS environment and provide standardized, simple and transparent operation. Details of the design, tests and beam measurements will be present. |
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| MOPD082 | GEM-TPC Trackers for the Super-FRS at FAIR | 888 |
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The Super-FRS is a superconducting fragment separator that will be built as part of the FAIR facility. For the slow-extraction part of the beam diagnostics system a total of 32 detectors are needed for beam monitoring and for tracking and characterization of the produced ions. Since GEM-TPC detectors can perform over wide dynamic range without disturbing the beam, they are suitable for this kind of in-beam detection. We have studied the performance of a prototype GEM-TPC. The current status of the prototype detector and the measurement results are shown. |
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| MOPD083 | Improvements of the Set-up and Procedures for Beam Energy Measurements at BESSY II | 891 |
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With a 7T wiggler in operation any attempts to detect the resonant depolarization of the electron spins were unsuccessful at BESSY II. This was attributed to the severely reduced final degree of spin polarization in the alternating fields of the strong wiggler which on the other hand nearly double the radiation loss per turn. The key to a clear detection of the depolarization were the improvement of the sensitivity of the polarimeter based on the spin dependent Touschek scattering cross section and the more effective and thus full depolarization of the beam. In the paper the steps taken will be presented in detail. With these improvements in place the high precision energy determination of the stored beam can be performed once again in parallel to the normal user operation and without any noticeable perturbations to the beam. |
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| MOPD084 | Highly sensitive beam size monitor for pA currents at the MLS electron storage ring | 894 |
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For the operation of the Metrology Light Source (MLS)*, the electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB), as a primary radiation source standard all storage ring parameters have to be known absolutely. For the measurement of the electron beam size and the monitoring of the stability of the orbit location a new imaging system has been set up, that operates at very different intensity levels covering more than 11 decades, given by the variation of the electron beam current. The system uses a commercial zoom lens for the achromatic optical imaging of the electron beam source point onto two different camera systems. One camera system is for life-imaging of the electron beam at electron beam currents from 200 mA down to some μA. The second system is a cooled CCD-camera that allows imaging of the electron beam size and location at very low currents, down to only one stored electron. * R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008). |
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| MOPD085 | Measurement and Correction of the Longitudinal and Transversal Tunes during the Fast Energy Ramp at ELSA | 897 |
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At the electron stretcher accelerator ELSA of Bonn University, an external beam of either unpolarized or polarized electrons is supplied to hadron physics experiments. In order to correct dynamic effects caused by eddy currents induced during the fast energy ramp, the transversal tunes have to be measured in situ with high precision. These measurements are based on the excitation of coherent betatron oscillations generated by a pulsed kicker magnet. Horizontal oscillations were excited using one of the injection kicker magnets. Since its installation in 2009 a newly designed kicker magnet enables measurements in the vertical plane as well. Betatron oscillation frequencies were derived from a fast Fourier transform of the demodulated BPM signals, showing a well pronounced peak at the tune frequency. Using this technique, tune shifts were measured and corrected successfully on the fast energy ramp. Measurement and correction of coherent synchrotron oscillations are feasible as well, utilizing a quite similar technique. Coherent synchrotron oscillations are excited by a phase jump of the acceleration voltage using an electrical phase shifter in the reference RF signal path. |
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| MOPD086 | Beam Position Monitoring Based on Higher Beam Harmonics for Application in Compact Medical and Industrial Linear Electron Accelerators | 900 |
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The usability of conventional BPM topologies in compact linear accelerators used for medical and industrial applications is very limited due to tight space restrictions in such systems. To overcome these limitations, a different approach is introduced which is based on integrating the pickups into low-field regions of the accelerating structure and evaluating higher beam harmonics. Applications based on this approach will require RF frontends in frequency ranges beyond those covered by BPM dedicated hardware which is currently commercially available. Therefore, a demonstrator setup is presented which is capable of investigating suitable RF frontends for the proposed method. The demonstrator uses capacitive pickups of the button type for displacement sensing and allows for control of the beam position with the help of feedback steering coils which are typically used for compact linacs. Representative sensitivity measurement results based on the evaluation of the 2nd S-Band beam harmonic are also presented in this paper. |
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| MOPD087 | Error Emittance and Error Twiss Functions in the Problem of Reconstruction of Difference Orbit Parameters by Usage of BPM's with Finite Resolution | 903 |
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The problem of errors, arising due to finite BPM resolution in the reconstructed orbit parameters, is one of the standard problems of the accelerator physics. Even so for the case of uncoupled motion the covariance matrix of reconstruction errors can be calculated "by hand", the usage of the obtained solution, as a tool for designing of a "good measurement system", is not straightforward. A better understanding of this problem is still desirable. We make a step in this direction by introducing dynamics into this problem, which seems to be static. We consider a virtual beam obtained as a result of the application of a reconstruction procedure to ‘‘all possible values'' of BPM reading errors. This beam propagates along the beam line according to the same rules as any real beam and has all beam dynamical characteristics, such as emittances, dispersions, betatron functions, and all these values describe the properties of the BPM measurement system. As an application we formulate requirements for the BPM measurement system of high-energy intra-bunch-train feedback system of the European XFEL Facility in terms of the introduced concepts of error emittance and error Twiss parameters. |
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| MOPD088 | Resolution Studies of Inorganic Scintillation Screens for High Energy and High Brilliance Electron Beams | 906 |
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Luminescent screens are widely used for particle beam diagnostics, especially in transverse profile measurements at hadron machines and low energy electron machines where the intensity of optical transition radiation (OTR) is rather low. The experience from modern linac based light sources showed that OTR diagnostics might fail even for high energetic electron beams because of coherence effects in the OTR emission process. An alternative way to overcome this limitation is to use luminescent screens, especially inorganic scintillators. However, there is only little information about scintillator properties for applications with high energetic electrons. Therefore a test experiment has been performed at the 855 MeV beam of the Mainz Microtron MAMI (University of Mainz, Germany) in order to study the spatial resolution. The results of this experiment will be presented and discussed in view of scintillator material properties and observation geometry. |
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| MOPD089 | PETRA III Diagnostics Beamline for Emittance Measurements | 909 |
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PETRA III is the new 3rd generation hard X-ray synchrotron light source at DESY, operating at a beam energy of 6 GeV. Machine commissioning began in April 2009 and user operation starts in 2010. In order to achieve a high brilliance, damping wigglers with a total length of 80 m are installed to reduce the horizontal emittance down to an extremely low value of 1 nm rad. For a precise emittance online control, a dedicated diagnostics beamline was built up to image the beam profile with synchrotron radiation from a bending magnet in the X-ray region. The beamline is equipped with two interchangeable X-ray optical systems, a pinhole optic for standard operation and a high resolution compound refractive lens optic. In addition, the synchrotron radiation angular distribution can be exploited at high photon energies. In this presentation, first experience with the system will be reported. |
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| MOPD090 | Upgrade and Evaluation of the Bunch Compression Monitor at the Free-electron Laser in Hamburg (FLASH) | 912 |
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The control and stabilization of RF systems for accelerators has a considerable importance. In case of high-gain free-electron lasers (FEL) with magnetic bunch compressors, the RF phases determine the attainable bunch peak current, which is a relevant parameter for driving the FEL process. In order to measure the bunch peak current in a simple and fast but indirect way, both bunch compressors at FLASH are equipped with compression monitors (BCM) based on pyroelectrical detectors and diffraction radiators (CDR). They provide substantial information to tune the bunch compression and are used for beam-based feedback to stabilize RF phases. This monitor system becomes more important and more challenging after the installation of a third-harmonic RF system for longitudinal phase space linearization in front of the first bunch compressor. In this paper, we describe the hardware upgrade of the bunch compression monitor and show the expected performance by simulations of the CDR source and the radiation transport optics. Particle tracking simulations are used for generation of the simulated BCM-signal for various compression schemes. Comparison with experimental data will be presented. |
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| MOPD091 | Femtosecond Temporal Overlap of Injected Electron Beam and EUV Pulse at sFLASH | 915 |
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sFLASH is a seeded FEL experiment at DESY, which uses a 38nm high harmonic gain (HHG)-based XUV-beam laser in tandem with FLASH electron bunches at the entrance of a 10m variable-gap undulator. The temporal overlap between the electron and HHG beams is critical to the seeding process. Use of a 3rd harmonic accelerating module provides a high current electron beam (at the kA level) with ~ 600fs FWHM bunch duration. The length of the HHG laser pulse will be ~30fs FWHM. The desired overlap is achieved in steps. First is the synchronization of the HHG drive laser (Ti: Sapphire, 800nm) and the incoherent spontaneous radiation from an upstream undulator. Next, the IFEL-modulated electron bunch will pass through a dispersive section, producing a density modulation in the beam. This in turn yields emission of coherent radiation from a downstream undulator or transition radiation screen when the longitudinal overlap of the two beams is achieved. The coherently enhanced light emitted will be then spectrally analyzed. The experimental layout, simulation results of generation and transport of both light pulses, and preliminary measurements are presented. |
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| MOPD092 | The Diagnostics System at the Cryogenic Storage Ring CSR | 918 |
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A cryogenic storage ring (CSR) is under construction at MPI für Kernphysik, which will be a unique facility for low velocity phase space cooled ion beams. Among other experiments the cooling and storage of molecular ions in there rotational ground state is planed. To meet this requirement the ring must provide a vacuum with a residual gas density below 10000 molecules/cm3, which will be achieved by cooling the vacuum chamber of the ion beam to 2-10 K. The projected stored beam current will be in the range of 1 nA - 1 μA. The resulting low signal strengths on the beam position pickups, current monitors and Schottky monitor put strong demands on these diagnostics tools. The very low residual gas density of the CSR does not allow using a conventional residual gas monitor to measure the profile of the stored ion beam. Other methods were investigated to measure the profile of a stored ion beam. In the paper an overview of the CSR diagnostics tool and diagnostics procedures will be given. |
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| MOPD093 | Nondestructive Beam Instrumentation and Electron Cooling Beam Studies at COSY | 921 |
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To study electron cooling in a synchrotron nondestructive methods only are suitable. The ionization profile monitor (IPM) delivers real-time data in both transverse planes allowing detailed analysis of beam profile evolution in COSY. First attempts to use scintillation of residual gas (SPM) to measure beam profiles were very promising. Beam diagnostics based on recombination is usually used to optimize electron cooling of protons (H0-diagnostics). However, it is not available when cooling antiprotons. So the IPM and possibly the SPM are vital for electron cooling optimization in the HESR ring. The new beam instrumentation at COSY is introduced and its relevance for the new 2 MeV electron cooler project and the HESR are discussed. Results of beam studies performed during electron cooling beam times at COSY are presented. |
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| MOPD094 | Single Bunch Operation at ANKA: Gun Performance, Timing and First Results | 924 |
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A new 90 kV e-gun had been installed at the 50 MeV microtron at ANKA. The emittance of the gun has been measured in long pulse mode (1 us, 200 mA) with a pepper-pot, resulting in 5 u.rad RMS normalised emittance. The single pulse width is less than 1 ns, resulting in a bunch purity in the storage ring of better 0.5 %. The old timing system for gun and injection elements based on 4 Stanford delay generator has now been replaced by an event driven system from Micro-Research Finland (MRF). This consists of one event generator and one event receiver. Visualisation and programming is achieved with PVSS from ETM Austria. The e-gun trigger can be adjusted in 10 ps steps. The entire system is phase locked to the 499.69 MHz RF signal. |
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| MOPD095 | Various Improvements to Operate the 1.5 GeV HDSM at MAMI | 927 |
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During the last three years at the 1.5 GeV Harmonic Double Sided Microtron (HDSM)* of MAMI a lot of improvements concerning the longitudinal operation of the accelerator were tested and installed. To monitor the rf power dissipated in the accelerating sections, their cooling water flow and its temperature rise are now continuously logged. Phase calibration measurements of the linacs and the rf-monitors revealed nonlinearities of the high precision step-motor driven waveguide phase shifters. They were recalibrated to deliver precise absolute values. Thereby it is now possible to measure not only the first turn's phase very exactly, but also determine the linac's rf-amplitude within an error of less than 5%, using the well known longitudinal dispersion of the bending system. These results are compared to the thermal load measurements. For parity violating experiments the beam energy has to be stabilised to some ppm. A dedicated system measuring the time-of-flight through a bending magnet is now used in routine operation and controls the output energy via the proper linac phases. * K.-H. Kaiser et al., NIM A 593 (2008) 159 - 170, doi:10.1016/j.nima.2008.05.018 |
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| MOPD096 | Plannar Microchannel Target | 930 |
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The analytic solution of a microchannel target for a uniform beam is given in one-dimentional model. The target surface temperature, maximum acceptable power density, and the function of various geometric parameter are deduced. The solution is modified for an axi-symmetric Gaussian beam. The analytic results are coincident with the numerical solution. A slit target used to measure beam energy spectrum for a beam with energy of 3.54MeV, average beam power of 36kW is developed. |
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| MOPD097 | FERMI@Elettra Low-Energy RF Deflector FEM Analysis | 933 |
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FERMI@Elettra is a soft X-ray fourth generation light source under construction at the ELETTRA laboratory. To characterize the beam phase space by means of measurements of the bunch length and of the transverse slice emittance two deflecting cavities will be positioned at two points in the linac. One will be placed at 250 MeV (low energy), after the first bunch compressor (BC1); the second at 1.2 GeV (high energy), just before the FEL process starts. The Low-Energy RF Deflector consists in a 5 cells, standing wave, normal conducting, RF copper cavity. A single ANSYS model has been developed to perform all of the calculations in a multi-step process. In this paper we discuss and report on results of electromagnetic, thermal, and structural analysis. |
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| MOPD098 | Fast IR Array Detector for Transverse Beam Diagnostics at DAΦNE | 936 |
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At the LNF of INFN an IR array detector with a ns response time has been built and assembled in order to collect the IR image of the e-/e+ sources at DAΦNE. Such detector is made by 32 bilinear pixels with a pixel size of 50x50 μm2 and a response time of 1 ns. The device with its electronic board has been assembled for the installation on the e+ ring of DAΦNE in the framework of an experiment funded by the INFN Vth Committee dedicated to beam diagnostics. A preliminary characterization of few pixels of the array and of the electronics has been carried out at the IR beamline SINBAD at DAΦNE. In particular the detection of the IR source of the e- beam has been observed using four pixels of the array acquiring signals simultaneously with a 4 channels scope at 1GHz and at 4 Gsamples/s. The acquisition of 4 pixels allowed monitoring in real time differences in the bunch signals in the vertical direction. Preliminary analysis of data is presented and discussed. In particular we will outline how the differences in the signals can be correlated to small displacements of the source after the bunch refilling and during a complete shift of DAΦNE and before the refilling of electrons. |
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| MOPD099 | High Brightness Beam Measurement Techniques and Analysis at SPARC | 939 |
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Ultra-short electron bunch production is attractive for a large number of applications ranging from short wavelength free electron lasers (FEL), THz radiation production, linear colliders and plasma wake field accelerators. SPARC is a test facility able to accelerate high brightness beam from RF guns up to 150 MeV allowing a wide range of beam physics experiments. Those experiments require detailed beam measurements and careful data analysis. In this paper we discuss the techniques currently used in our machine; by combining quadrupoles, RF deflector, spectrometer dipole and reliable data analysis codes, we manage to characterize the 6D phase space and the beam slice properties. We focus on the ongoing studies on the emittance compensation in the velocity bunching regime. |
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| MOPD102 | Space Charge Analysis on the Multi-wire Proportional Chamber for the High Rate Incident Beams | 942 |
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For the beam profile diagnosis of heavy ion cancer therapy in HIMAC (Heavy Ion Medical Accelerator in Chiba), a MWPC (Multi-Wire Proportional Counter) detector is employed as a beam profile monitor. Due to the high rate beams (~ 108 pps), a gain reduction of output signals, which is caused by space charge effects, have been observed in the scanning beam experiments at HIMAC. In order to reduce the gain reduction by optimizing the parameters of MWPCs including anode radius, and distance between electrodes, a numerical calculation code was developed by employing two-dimensional fluid model. In order to understand the relations between the gain reduction and space charge distribution, the temporal evolution of the ion/electron distribution were calculated for several hundredμseconds, which is significantly longer than the time period required for ions to travel between the electrodes. The output signal was also evaluated by the current flux into the anode and compared with that obtained by the beam experiment at HIMAC. The dependence of the gain reduction on the MWPC parameters was analyzed from these calculation results. |
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| MOPD103 | Development of an Apparatus for Measuring Transverse Phase-space Acceptance | 945 |
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It is important to match the injection beam emittance to the acceptance of an accelerator for high beam transmission A system to evaluate transverse beam matching has been developed in the JAEA AVF cyclotron facility. In this presentation, concepts of an apparatus for transverse acceptance measurement will be reported. The apparatus consists of a phase-space collimator in the injection beam line and beam current monitor after the cyclotron. The collimator consists of two pairs of position defining slits and angle defining slits to inject an arbitrarily small portion of transverse phase-space into the cyclotron. Measurement of the acceptance is made by testing every portion in the whole phase-space, which should large enough to cover the acceptance. The acceptance can be estimated from the sum of the portions of the beam which passes through the system. |