| Paper | Title | Page |
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| THPMN002 | Nonlinear Dynamics of Electromagnetic Pulses in Cold Relativistic Plasmas | 2707 |
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Funding: CNPq, Brasil In the present analysis we study the self consistent propagation of nonlinear electromagnetic pulses in a one dimensional relativistic electron-ion plasma, from the perspective of nonlinear dynamics. We show how a series of Hamiltonian bifurcations give rise to the electric fields which are of relevance in the subject of particle acceleration. Nonlinear coupling of plasma waves and electromagnetic pulses triggers strong chaotic dynamics which may detrap the plasma wave from the electromagnetic pulse, leading to wave breaking. Connections with results of earlier analysis are discussed. |
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| THPMN003 | Commissioning of the 100 keV Beam Stage of the Injector Linac of the IFUSP Microtron | 2710 |
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Funding: Work supported by FAPESP and CNPq The injector linac consists of a beam conforming stage, with chopper and buncher systems, and two acceleration structures, the first one with variable β, and the second one divided into two parts with different β. There are two 3-mm diameter collimators, the first at the entrance to the first chopper cavity and the second at the entrance to the first acceleration structure. The beam focalization is made by solenoids, and correcting coils are provided for steering. In this work we describe the commissioning of the optical lattice of the conforming beam stage. The first beam images are shown. |
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| THPMN004 | A Synchrotron Based Particle Therapy Accelerator | 2713 |
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| Danfysik and Siemens have entered a cooperation to market and build Particle Therapy* systems for cancer therapy. The accelerators will consist of an injector (7 MeV/u proton and light ions), a compact and simple synchrotron and a choice of fixed-angle horizontal and semi-vertical beamlines together with gantry systems. The optimized lattice configuration, including the design of injection and extraction systems, provides large transverse phase space acceptance with minimum magnet apertures. The resulting synchrotron will have light magnets, low values of peak power for pulsed operation and minimum dc power consumption. The beam can be accelerated to the maximum magnetic rigidity of 6.6 Tm in less than 1 s. A beam of 48-250 MeV protons and 88-430 MeV/u carbon ions can be slowly extracted during up to 10s. The intensity for protons and carbon ions will be well beyond the needs of scanning beam applications. The design and performance specs of the synchrotron will be described in detail including simulations. Design and manufacture of the subsystems are in progress. *Particle Therapy is a work in progress and requires country-specific regulatory approval prior to clinical use. | ||
| THPMN005 | Technical Challenges for Head-On Collisions and Extraction at the ILC | 2716 |
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Funding: EUROTeV Project Contract no.011899 RIDS An interaction region with head-on collisions is considered as an alternative to the baseline ILC configuration. Progress in the final focus optics design includes engineered large bore superconducting final doublet magnets and their 3D magnetic integration in the detector solenoids. Progress on the beam separation optics is based on technical designs of electrostatic separator and special extraction quadripoles. The spent beam extraction is realized by a staged collimation scheme relying on realistic collimators. The impact on the detector background is estimated. The possibility of technical tests of the most challenging components is investigated. |
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| THPMN006 | Modification and Measurement of the Adjustable Permanent Magnet Quadrupole for the Final Focus in a Linear Collider | 2719 |
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Funding: This research was partially supported by JSPS, Grant-in-Aid for Scientific Research, 14204023-2002, 18204023-2006 and the U. S. DOE under contract DE-AC02-76SF00515. An adjustable permanent magnet quadrupole has been developed for the final focus in an electron-positron linear collider. The design has two concentric rings of permanent magnets. Recent activities include a newly fabricated inner ring that demonstrates the strongest field gradient at a small bore diameter of 15mm and a new magnetic field measurement system based on a rotating coil. The prospects of the R&D will be discussed. |
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| THPMN008 | Evaluation of Luminosity Reduction in the ILC Head-on Scheme from Parasitic Collisions | 2722 |
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| An interaction region with head-on collisions is being developed for the ILC as an alternative to the base line 14 mrad crossing angle design, motivated by simpler beam manipulations upstream of the interaction point and a more favourable configuration for the detector and physics analysis. The design of the post-collision beam line in this scheme involves however a number of technological challenges, one of which is the strength requirement for the electrostatic separators placed immediately after the final doublet to extract the spent beam. In this paper, we examine in detail the main mechanism behind this requirement, the multi-beam kink instability, which results from the long-range beam-beam forces at the parasitic crossings after the bunches have been extracted. Our analysis uses realistic bunch distributions, the Guinea-Pig program to treat beam-beam effects at the interaction point and the DIMAD program to track the disrupted beam distributions in the post-collision beam line. A version of the beam-beam deflection based interaction point feedback system with an improved filtering algorithm is also studied to mitigate the luminosity deterioration from the instability. | ||
| THPMN009 | Backscattering of Secondary Particles into the ILC Detectors from Beam Losses Along the Extraction Lines | 2725 |
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| At the International Linear Collider (ILC) the beams will be focused to extremely small spot sizes in order to achieve the desired luminosity. After the collision the beams must be brought to the dump with minimal losses. In spite of all the attention put into the design of the extraction line, the loss of some disrupted beam particles, beamstrahlung or synchrotron radiation photons is unavoidable. These losses will generate low-energy secondary particles, such as photons, electrons and neutron, a fraction of which can be back-scattered towards the interaction point and generate backgrounds into the detector. In this paper we present an evaluation of such backgrounds, using the BDSIM and Mokka simulations, for several presently considered ILC extraction lines and detectors. | ||
| THPMN010 | GUINEA-PIG++ : An Upgraded Version of the Linear Collider Beam-Beam Interaction Simulation Code GUINEA-PIG | 2728 |
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| GUINEA-PIG++ is a newly developed object-oriented version of the Linear Collider beam-beam simulation program GUINEA-PIG. The main goals of this project are to provide a reliable, modular, documented and versatile framework enabling convenient implementation of new features and functionalities. Examples of improvements described in this paper are an easy interface to study the impact of electromagnetic effects on Bhabha event selections, a treatment of spin depolarization effects, automatic consistency checks and adjustments of internal computational parameters, upgraded input/output and user interface, an optimised setup for massive production on distributed computing GRIDs. A possible setup to perform fast parallelised computations is also discussed. | ||
| THPMN012 | A 0.5 to 50 MeV Electron Linear Accelerator System | 2731 |
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| Since 1998 ACCEL delivers turn key accelerator for scientific applications. After three injector systems for synchrotron light sources have been successfully commissioned, ACCEL is currently producing a 5 to 50 MeV system for the German Metrological Institute in Braunschweig. Beside excellent beam energy qualities the accelerator has to operate in a wide energy range, delivering 1 to 100 W average beam power to the target. The paper will give a description of the system layout and related technical parameters. The status of the project and results of the factory acceptance test of some of the major components will be presented as well. | ||
| THPMN014 | Commissioning of the Linac for the Heidelberg Heavy Ion Cancer Therapy Centre (HIT) | 2734 |
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| A clinical facility for cancer therapy using energetic proton and ion beams (C, He and O) is under construction and will be installed at the Radiologische Universitätsklinik in Heidelberg, Germany. It consists of two ECR ion sources, a 7 MeV/u linac injector, and a 6.5 Tm synchrotron to accelerate the ions to final energies of 50-430 MeV/u. The linac comprises a 400 keV/u RFQ and a 7 MeV/u IH-DTL operating at 216.8 MHz. The commissioning of the linac with beam was performed in three steps for the LEBT, the RFQ, and the IH-DTL. For this purpose a versatile beam diagnostic test bench has been used consisting of a slit-grid emittance measurement device, transverse pick-ups providing for time of flight energy measurements, SEM-profile grids, and different devices for beam current measurements. In this contribution the procedure and the results of the successful commissioning in the year 2006 of the linear accelerator are reported. | ||
| THPMN015 | Longitudinal Electrode Voltage Distribution on a 4-rod RFQ Simulation Model | 2737 |
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| For a proper working RFQ with minimized particle losses, a constant longitudinal voltage distribution on the electrodes is needed. This assures a sufficient compensation of the beam space change. The local electrode voltage and its change is mainly given by the varying aperture of the quadrupole and in consequence the changing local capacity. The simulation of the RFQ model with modulated electrodes is a very complex thread. An example for such a model will be given here. | ||
| THPMN016 | Study of Fill Patterns for the ILC Electron Damping Ring | 2739 |
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Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899 Ion effects are detrimental to the performance of the electron damping ring for the International Linear Collider (ILC). Irregular bunch patterns, e.g. short bunch trains with interleaved gaps, are an effective way to alleviate ion effects. In this paper, we discuss the fill patterns and their impact on the ion effects for the ILC electron damping ring. |
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| THPMN017 | Polarized Positron Production and Tracking at the ILC Positron Source | 2742 |
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Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. A positron source based on a helical undulator system is planned to be used for the future International Linear Collider (ILC). Depending on the accelerator design it will be possible to get polarized positrons at the interaction point. A source performance with high positron yield and high polarization is the aim of our design studies. We focus on the optimization of target and capture section using several simulation codes. FLUKA is a suitable tool to calculate the positron yield, heat deposition, neutron generation and induced activity of source parts. The ASTRA code is used to calculate positron capture efficiency into the optical matching device. The new release of Geant4 includes the spin dependence of all QED processes and allows to perform a helicity-dependent tracking of particles through target and capture section. Starting with a cross-check, the synergy of these three codes allowed to specify the the parameters of a polarized positron source. |
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| THPMN019 | Morphological Changes of Electron-beam Irradiated PMMA Surface | 2745 |
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Funding: Author are thankful to DAE-BRNS, India for financial support for research work Atomic force microscopy (AFM) study of low energy (10 keV) electron beam irradiated Polymethylmethacrylate (PMMA)20 micron thick surface was performed. PMMA film has been used in lithography applicatiion by this technique. AFM in tapping mode has been utilized to investigate the morphological changes on the samples surface as a function of fluence. TM-AFM showed the hills of the nano size surrounded by the craters type features in all the irradiated samples. The shape and size of these features varied with fluence. The root-mean-square (rms) surface roughness of the samples changed from 2.666 nm to 5.617 nm with fluence from 2x1014 electrons/cm2 to 1x1016 electrons/cm2. It shows that roughness increases as increasing fluence. |
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| THPMN020 | Design Studies of the 300 AMeV Superconducting Cyclotron for Hadrontherapy | 2748 |
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| A design study of a compact superconducting cyclotron for hadrontherapy is carrying out at Laboratori Nazionali del Sud of Catania. This machine is able to accelerate light ions with a charge to mass ratio of 0,5 up to the maximum energy of 300 AMeV. Light ions like Carbon will be extracted by an electrostatic deflector at the energy of 3,6 GeV. The range of this beam is of 174 mm in water and is enough to threat all the tumors of the head and neck district. Despite the machine is able to accelerate also the ionised hydrogen molecule up to 300 AMeV, an extraction by stripping allow us to deliver a proton beam with energy of 250 MeV. The range in water of proton beam with this energy being 370 mm. The main parameters of the cyclotron and the main features of the beam dynamics will be presented. | ||
| THPMN021 | Ultrafast Beam Research at the Pegasus Laboratory | 2751 |
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| The PEGASUS laboratory at the UCLA Physics Department is a photoinjector laboratory. With a new ultrafast photoinjector laser driver, the laboratory capabilities are greatly expanded. We discuss the near term scientific goals and technical solutions proposed. The marriage of ultra short laser pulse techniques and a high brightness electron source allows also the development of advanced longitudinal beam diagnostics with time-resolution comparable to the ultrashort laser probe pulse derived from the photocathode driver. | ||
| THPMN022 | Going Towards the Dual Energy X-Ray Radiographic System for Material Recognition Purposes | 2754 |
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| Non Destructive Testing (NDT) has become the most used technique to inspect objects in order to find manufacturing defects (quality control), investigate contents (custom control), detect damages (structural control). However, the mono-energetic NDT can only discover a density variation in the analyzed sample but in most cases no hypothesis can be done on its composition; a complete inspection of an object would require the recognition of the material composing the analyzed sample and this can be achieved by means of the dual energy x-ray radiography. In this context, the INFN Gruppo Collegato di Messina is implementing the radio-tomographic system of the Universita di Messina, based on a 5 MeV electron linac, to the aim to provide dual energy x-ray beams for material recognition purposes. A wide study has been performed to provide different electron energies acting on the linac parameters. According to a theoretical study on the x-ray transmission for two properly chosen x-ray energies, preliminary tests have been performed to evaluate the complementarity of the images obtained with the dual energy technique. Work is still in progress to improve the dual energy system. | ||
| THPMN023 | Study of an Electron Linac Driven X-Ray Radio-Tomographic System Response as a Function of the Electron Beam Current | 2757 |
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| At the Dipartimento di Fisica, Universita di Messina, a high energy x-ray radio-tomography system driven by a 5 MeV electron linac, has been recently assembled. It has been tested and has already provided good results in inspecting heavy materials. In order to achieve good radiographic results, especially when inspecting heavy or thick materials, an enhancement of the x-ray dose at the sample position can be required and most of times this is associated to an enhancement of the grey level in the acquired image according to a linear function. Nevertheless, in the hypothesis to work at the maximum magnetron power, a variation of the x-ray dose, obtained changing the electron beam current, is associated to a variation of the electron beam energy. As a consequence, the x-ray energy spectrum varies thus influencing the response of the radio-tomographic system. This does not allow a linear correspondence between the x-ray fluence (or the electron beam current) and the image grey level. By means of MCNP-4C2 simulations, the influence of electron beam energy variations on the produced bremsstrahlung spectrum has been studied and the theoretical results have been experimentally confirmed. | ||
| THPMN024 | A Study for the Characterization of High QE Photocathodes | 2760 |
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Funding: Work supported by the European Community, contract number RII3-CT-2004-506008 Based on our experience on photocathode production, we present in this paper the results of the application of different optical diagnostic techniques on fresh and used photocathodes. These techniques allow to study effects like non uniformity, cathode aging, etc. In particular, photocathode optical parameters and QE characterization, both done at different wavelengths, give fundamentals information for the construction of a model of the photoemission process to be applied to Cs2Te photocathodes. These studies are useful for further improving key cathode features, such as its robustness and lifetime as well as to study and control the photocathodes thermal emittance. |
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| THPMN025 | High QE Photocathodes Performance during Operation at FLASH/PITZ Photoinjectors | 2763 |
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Funding: Work supported by the European Community, contract number RII3-CT-2004-506008 The FLASH (DESY-Hamburg) and PITZ (DESY-Zeuthen) photoinjectors routinely use high quantum efficiency (QE) photocathodes produced at LASA (INFN-Milano), since 1998. To further understand the photocathode behavior during beam operation, photocathode QE measurements have been performed at different operating conditions in both RF photoinjectors. The analysis of these measurements will be used to improve the photocathode preparation procedures and to deeper understand the photocathode properties, whose final goal would be the further increase of their lifetime and beam quality preservation during the RF gun operations. |
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| THPMN026 | C-band Linac in SCSS Prototype Accelerator of the Japanese X-FEL Project | 2766 |
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Funding: RIKEN-JASRI Joint-Project for SPring-8 XFEL C-band (5712-MHz) linac is used as the main accelerator of the Japanese X-FEL facility in SPring-8. Since the C-band linac has high acceleration gradient, our 8-GeV accelerator is compact rather than a conventional S-band accelerator. The system consists of following components; two choke-mode-type 1.8-m accelerating structures, an rf pulse compressor (SLED), a 50-MW klystron, a 100-MW compact modulator, and an rf digital control system. We will use 60 to 70 units for the X-FEL accelerator. Since November 2005, we have operated two C-band units in the 250-MeV FEL prototype accelerator (SCSS). After rf conditioning, the accelerating gradient was achieved to 35-MV/m. We successfully accelerated the electron beam by this gradient of electrical field. In this presentation, we will report the detail of each component and its operation status of the SCSS prototype accelerator. |
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| THPMN027 | Status of C-band Accelerator Module in the KEKB Injector Linac | 2769 |
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| For future upgrade of the KEKB injector linac, components of C-band accelerator module have been developed since 2002. A prototype C-band accelerator module composed of a 50-MW klystron, an RF-pulse compressor and four 1-m long accelerating sections, has been constructed in the present S-band injector linac. It has been operated for 14 months. In a recent beam-acceleration study, it has achieved an energy gain of 151 MeV, which corresponds to an average acceleration field of 39 MV/m. | ||
| THPMN028 | Development of the Strip-line Kicker System for ILC Damping Ring | 2772 |
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| The performance of the kicker system for the International Linear collider(ILC) is the one of the key component to determine the damping ring(DR) circumference and the train structure. The parameters are discussing at the baseline configuration design for the ILC. The bunch trains in the linac are 2820(5640) bunches with 308(154) ns spacing and the repetition rate is 5Hz. The bunch spacing in the DR is 6(3) ns. The kicker has to have fast rise and fall times of 6(3) ns and the repetition rate of 3.25(6.5) MHz. The development work of the kicker system using multiple strip-lines is carried out at KEK-ATF. The beam test result of the single unit is described. Also Experimental results on new scheme to improve the rise and fall times will be presented. | ||
| THPMN029 | A DC/Pulse Electron Gun with an Aperture Grid | 2775 |
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| A new thermionic-electron gun for a high-brightness X-ray source is under development. Its extraction voltage and design current are 60 keV and 100 mA, respectively. In order to focus beams on a metal target within 1.0 x 0.1 mm2, it is required for the emittance of a beam to be small. A grid electrode is not an orthodox mesh grid but an aperture grid. An increase of the beam emittance and heat generation at a grid will be surpressed. Electrodes dimensions such as shape of Wehnelt electrode and a shape of an aperture grid are determined by the EGUN simulation and parameters were optimized. In this paper a result of beam examination will be reported. | ||
| THPMN030 | Enhancement of the Positron Intensity by a Tungsten Single Crystal Target at the KEKB Injector Linac | 2778 |
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Funding: This work was supported by the Grant-in-Aid of Ministry of Education, Culture, Sports, Science and Technology of Japan and by the grant of Ministry of Education and Science of the Russian Federation. A new tungsten single-crystalline positron target has been successfully employed for generation of the intense positron beam at the KEKB injector linac in September 2006. The target is composed of a tungsten single-crystal with a thickness of 10.5 mm. The positron production target is bombarded at an incident electron energy of 4 GeV, and the produced positrons are collected and accelerated up to the final injection energy of 3.5 GeV in the succeeding sections. A conventional tungsten plate with a thickness of 14 mm has been used previously, and the conversion efficiency (Ne+/Ne-), the ratio between the number of positrons (Ne+) captured in the positron capture section and the number of the incident electrons (Ne-), was 0.20 on average. By replacing the tungsten plate with the tungsten crystal, it increased to 0.25 on average. The increase of the conversion efficiency has boosted the positron intensity to its maximum since the beginning of KEKB operation in 1999. Now this new positron source is stably operating and is contributing to increasing the integrated luminosity of the KEKB B-factory. |
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| THPMN031 | Experiment of X-Ray Source by 9.4 GHz X-Band Linac for Nondestractive Testing System | 2781 |
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| We are developing a compact X-ray source for Nondestractive Testing (NDT) system. We aim to develop a portable X-ray NDT system by 950 keV X-band linac to realize in-site inspection. Our system has 20 kV electron gun, and accelerate electron beam to 950 keV with 9.4 GHz X-band linac. RF source of this system is 250kW magnetron. Our target spot size and spatial resolution are 1mm. We adopted APS (Alternative Periodic Structure) tube of pi/2 mode for easy manufacturing. It is difficult to realize a high-shunt-impedance for low-energy-cells, which attributes to manufacturing problems. Instead, we use three pi-mode cavities there. Further, we choose the low power magnetron for small cooling system and the low voltage electron gun for small power supply. For the stability of the X-ray yield the system include the Auto Frequency Control (AFC), which detect and tune the frequency shift at the magnetron. We have also performed X-ray generation calculation by the Monte Carlo code of GEANT and EGS to confirm the X-ray source size. We are going to construct the whole system and verify it experimentally. Updated results are presented at the spot. | ||
| THPMN032 | Beam Generation and Acceleration Experiments of X-Band Linac and Monochromatic keV X-Ray Source of the University of Tokyo | 2784 |
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| In the Nuclear Professional School, the University of Tokyo, we are constructing an X-band linear accelerator that consists of an X-band thermionic cathode RF gun and X-band accelerating structure. This system is considered for a compact inverse Compton scattering monochromatic X-ray source for the medical application. The injector of this system consists of the 3.5-cell coaxial RF feed coupler type X-band thermionic cathode RF gun and an alpha-magnet. The X-band accelerating structure is round detuned structure (RDS) type that developed for the future linear collider are fully adopted. So far, we have constructed the whole RF system and beam line for the X-band linac and achieved 2 MeV electron beam generation from the X-band thermionic cathode RF gun. In addition, we achieved 40 MW RF feeding to the accelerating structure. The laser system for the X-ray generation via Compton scattering was also constructed and evaluated its properties. In this presentation, we will present the details of our system and progress of beam acceleration experiment and the performance of the laser system for the Compton scattering experiment. | ||
| THPMN033 | Commissioning a Cartridge-Type Photocathode RF Gun System at University of Tokyo | 2787 |
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| We have been developing a compact-sized cartridge-type cathode exchanging system installed in BNL-type IV photocathode RF gun. We can replace a cathode without breaking the vacuum of RF gun, so that a high quantum efficiency photocathode is not surrounded by oxygen or moisture. The advantage of this system can be controlled the quality of the each cathode by making cathode plugs in a factory. Moreover we can easily change a cathode material, such as visible light driven cathode (AgOCs NaK2Sb) the high QE cathode(Cs2Te) for high brightness beam, metal cathode(Mg) for ultra-fast phenomena. Therefore we can investigate characterization of variable cathode materials in high gradient electric field of ~100MV/m. The cavity with the exchanging port and the beam trajectory is calculated by superfish and GPT, respectively. We found that the parameters of the cavity with a plug is almost same compared with normal back plate. Using this system, we can investigate the cathode material and deliver the stable electron beam by one RF gun. | ||
| THPMN034 | Manipulation of Electron Beam Generation with Modified Magnetic Circuit on Laser-wakefield Acceleration | 2790 |
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| Electron beam injection triggered by intense ultrashort laser pulses, which is called as plasma cathode, is presented. We have studied generation of relativistic electrons by interaction between a high intensity ultra-short laser pulse and gas jet. When a static magnetic field of 0.2 T is applied, the modification of the preplasma cavity, and significant enhancement of emittance and an increase of the total charge of electron beams produced by a 12 TW, 40 fs laser pulse tightly focused in a He gas jet, were observed. And very high stability and reproducibility of the characteristics and position of well-collimated electron beams was detected. Now we are planning to experiment with a magnetic circuit that has more intense magnetic field of 1 T. The present report aims at presenting these experimental and analytical results. | ||
| THPMN035 | Pinpoint keV/MeV X-ray Sources for X-ray Drug Delivery System | 2793 |
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| X-ray Drug Delivery System (DDS) is the most advanced radiation therapy coming after IMRT (Intensity Modulated Radiation Therapy) and IGRT (Image Guided). DDS uses advanced nano-scaled polymers which contain and deliver drug or contrast agent to cancers without side effects. Several X-ray DDS poses high-Z atoms like Pt and Au to absorb X-rays effectively and used as contrast agent for inspection. Moreover, they have radiation enhancement effect by emission of Auger electron and successive characteristic X-rays. The enhancement factor off Pt and Au is more than five. This can be used for therapy. This new modality must be very important for inspection and therapy of deep cancers. We are making use of our Compton scattering monochromatic keV X-ray source and MeV linac aspinpoint keV/MeV X-ray sources for the purpose. Physical analysis and evaluation of the contrast efficiency and radiation enhancement of the X-ray DDS are under way. Furthermore, a new compact X-band linac with a multi-beam klystron for a pinpoint X-ray source is proposed and designed. Updated research status and result are presented. | ||
| THPMN036 | Simulation Study on Attosecond Electron Bunch Generation | 2796 |
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Pulse radiolysis, a stroboscopic method with an ultrashort electron bunch and an ultrashort light, is essential for the observation of ultrafast reactions. The time resolution of pulse radiolysis depends on the electron bunch length. In Osaka University, a 98-fs electron bunch was generated by using a photocathode electron linac for a development of femtosecond pulse radiolysis*. Furthermore, a sub-femtosecond/attosecond pulse radiolysis will be proposed to study the ionization and thermalization processes in attosecond time region. In order to realize such a high time resolution, the possibility of attosecond electron bunch generation based on the photocathode RF gun linac and a magnetic bunch compressor was studied. In the simulation, the bunch length growth due to charge, emittance, accelerating phase and magnetic fields were investigated to generate an attosecond electron bunch.
* J. Yang, T. Kondoh, K. Kan, T. Kozawa, Y. Yoshida and S. Tagawa: Nucl. Instrum. Methods Phys. Res., Sect. A 556 (2006) 52-56 |
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| THPMN037 | Development of Compact EUV Source based on Laser Compton Scattering | 2799 |
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High-power extreme ultraviolet (EUV) source is required for next generation semiconductor lithography. We start to develop a compact EUV source in the spectral range of 13-14 nm, which is based on laser Compton scattering between a 7 MeV electron beam and a high intensity CO2 laser pulse. Electron beam is pre-bunched using two different wavelengths of laser pulses with a dispersion section of beam transport line*,**. In this conference, we describe the results of numerical study for the EUV source and a plan of test experiment generating micro-bunched electron beam.
*M. Goldstein et al., Proc. of the 27th Int. FEL conference, Stanford, California, USA (2005) pp.422-425**A. Endo, Sematic EUV source workshop, Barcelona, Spain (2006) |
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| THPMN038 | Dynamic Optical Modulation of the Electron Beam for the High Performance Intensity Modulated Radiation Therapy | 2802 |
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| Radiation therapy attracts attention as one of cancer therapies nowadays. Recently, the radiation therapy of cancer is developing to un-uniform irradiation as IMRT, for reduce dose to normal tissue and concentrate dose to cancer tissue. A photo cathode RF gun is able to generate a low emittance electron beam pulse using a laser light pulse. We thought that a photo cathode RF gun can generate intensity modulated electron beam by optical modulation at the incident optics dynamically. Because of a low emittance, the modulated electron beam pulse is able to accelerate keeping shape. Accelerated electron pulses will be converted to X-ray pulses by a metal target bremsstrahlung method or by a laser inverse Compton scattering method. For the high performance intensity modulated radiation therapy (IMRT), dynamic optical modulation of the electron beam pulse were studied using a Photo cathode RF gun LINAC. Modulated and Moving electron beam will be reported. | ||
| THPMN039 | Femtosecond Electron Beam Dynamics in Photocathode Accelerator | 2805 |
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| Ultrashort electron beams, of the order of 100 fs, are essential to reveal the hidden dynamics of intricate molecular and atomic processes in nanofabrication through experimentation such as time-resolved electron diffraction and femto-chemistry. The transverse and longitudinal dynamics of ultrashort electron beam in a photocathode linear accelerator were studied for femtosecond electron beam generation. The emittance growth and bunch length increase due to the rf and the space charge effects in the rf gun were investigated with the laser injection phase. The dependences of the emittance, bunch length and energy spread on the bunch charge were measured experimentally and compared with the theoretical simulation. The increase of the bunch length due to the space charge effect was also investigated during the bunch compression in magnetic field. | ||
| THPMN040 | Development of an S-band Cs2Te-Cathode RF Gun with New RF Tuners | 2808 |
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| We have been studying an S-band Cs2Te-Cathode RF Gun with 1.6 cells. The new gun cavity reported in this poster has new RF tuners, which are compact and, therefore, can be attached even on the half-cell. RF balance between the full- and half-cells is adjustable by using the tuners on both cells. Compared to the existing cavity, a Helicoflex seal for half-cell adjustment is not needed for new one. This structure is expected to have advantages for gun machining, for Q factor of the cavity, and for reduction of dark current from the RF gun. The cathode is made by evaporation on a Mo plug, and the plug is attached by a load lock system. We report status of the gun development. | ||
| THPMN042 | Design of a 200keV High Pulse Current Electron Beam Facility | 2811 |
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| In the paper, design of a 200keV high pulse current electron beam facility is introduced, which is used to generate plasma by interaction between electron beam and gas. Physical parameters of the beam have been selected to satisfy the plasma experiment's need. LaB6 is chosen as cathode because of its high efficient emission and long lifetime. Temperature distribution simulation in the facility has been finished with I-deas code. Because the maximum working temperature in the system is 2400°C, grid is made of heat-resistant metal Mo. In order to get high pulse current and line shaping electron beam, shape of electrodes has been optimized. Electric field distribution in the system and process of electron beam emission have been simulated with opera-3d, which considering space charge effects. Ceramic flange's electrics and mechanics properties have also been analyzed. Metal foil window is made of titanium with 40μm thickness. Relationship between initial energy and energy loss of the electron beam has been obtained by MC simulation during passing through the window. Making of the facility has been finished and some parameters have been measured through testing experiments. | ||
| THPMN045 | Design and Control of Emittance Growth of Short Bunch Compressor for International Linear Collider | 2814 |
| We present an alternative design with the short system length in the bunch compressors for the International Linear Collider(ILC). We show the characteristics and performances of the designed system in detail. We also present orbit and dispersion correction schemes for the compensation of emittance growths, vertical dispersion and skew-component that may be generated by several machine errors in the system. In result, it is shown that the short bunch compressor system satisfies the required beam conditions for the ILC. | ||
| THPMN046 | Conceptual Design of the PEFP Rapid Cycling Synchrotron | 2817 |
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Funding: *This work was supported by the 21C Frontier R&D program sponsored by Ministry of Science and Technology, Korean Government The Proton Engineering Frontier Project (PEFP) is a research project to develop a 100 MeV, 20 mA pulsed proton linear accelerator to be used in basic/applied scientific R&D programs and industrial applications. The PEFP proposes the 1.0 GeV synchrotron accelerator as an extension of the PEFP linac, which is a 30 Hz rapid-cycling synchrotron (RCS) with the injection energy of 100 MeV. The target beam power is 87 kW at 1.0GeV in the first stage. The high intensity RCS is one of the important challenges for the spallation neutron source. The conceptual lattice design of the RCS as well as the simulations of an injection system is described in this paper. |
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| THPMN047 | Commissioning Scenario for L-band Electron Accelerator by PARMELA Code | 2820 |
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Funding: Work supported by KAPRA and PAL An intense L-band electron accelerator is now being installed at PAL (Pohang Accelerator Laboratory) for initial tests. It is capable of producing 10-MeV electron beams with average 30 kW. This accelerator has a diode-type E-gun, a pre-buncher cavity, and an accelerating column with the built-in bunching section. We conduct simulational study for the commissioning scenario by the PARMELA code. At first, we observe the beam position and the beam current when the beam line is misaligned under no fields. Next, turning on focusing solenoids we observe the beam position change to check the alignments of the solenoids. Finally, varying RF power and phase of the pre-buncher we observe beam energy and beam power to obtain the optimum pre-buncher condition. In this paper, we present simulational results for each step. We also present commissioning strategies based on these results. |
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| THPMN048 | Cold Test on C-band Standing-wave Accelerator | 2823 |
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Funding: Work supported by PAL. For a compact X-ray source, we designed a C-band standing-wave electron accelerator. It is capable of producing 4-MeV electron beams with 50-mA peak beam current. As an RF source, we use 5-GHz magnetron with duty factor of 0.08%. The accelerating structure is bi-periodic and on-axis coupled structure, operated with π/2-mode standing waves. Each cavity in the bunching and normal cell is designed by the MWS code and measured with aluminium prototype cavity. As per the dispersion relation derived from the measurement results, calibration factor obtained for the actual copper cavity. |
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| THPMN049 | Current Status of Intense L-band Electron Accelerator for Irradiation Source | 2826 |
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Funding: Work supported by KAPRA. An intense L-band electron accelerator is designed and under development for CESC (Cheorwon Electron-beam Service Center) irradiation applications. It is capable of producing 10-MeV electron beams with average 30 kW. For an RF source, a Thales klystron is used with 1.3 GHz, pulsed 25 MW, and average 60 kW. The accelerator column, fabricated by IHEP in China, is operated with 2π/3 mode traveling-wave under the fully-beam-loaded condition. The modulator was fabricated with inverter power supplies. The klystron was assembled to the klystron tank with pulse transformer. The high-voltage pulse test was conducted for the klystron tube. In this paper, we present design details of the accelerator and current status. |
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| THPMN055 | Effect of Amplification of Cherenkov Radiation in an Active Medium with Two Resonant Frequencies | 2829 |
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Funding: Russian Foundation for Basic Research; Ministry of Education and Science of Russian Federation.
The possibility of using an active medium to amplify the generated wakefield of an electron beam and employing the amplified wakefield to accelerate a second beam has been recognized recently*. This acceleration scheme is one of several related methods referred to as the Particle Acceleration by Stimulated Emission of Radiation (PASER). However, only the case of an active medium with a single resonant frequency has been analyzed until now. In this paper we present the results of analytical and numerical studies of Cherenkov radiation (CR) in an active medium with two resonant frequencies. We show that this medium can amplify CR even in the case of a purely real refractive index. In contrast to a medium with a single resonant frequency the amplification effect takes place in the absence of metal boundaries but only for sufficiently strong restrictions on the parameters of the medium. The amplification can be effective even for a medium with a relatively small inversion. Examples of CR amplification are given for several active materials. The effect may be useful both for wakefield accelerators and Cherenkov detectors.
*L. Schachter, Phys. Rev., E, 62, 1252 (2000); N. V.Ivanov, A. V.Tyukhtin, Tech. Phys. Lett., 32, 449 (2006). |
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| THPMN056 | Comparison of ILC Fast Beam-Beam Feedback Performance in the e-e- and e+e- Modes of Operation | 2832 |
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| Several feedback loops are required in the Beam Delivery System (BDS) of the International Linear Collider (ILC) to preserve the luminosity in the presence of dynamic imperfections. Realistic simulations have been carried out to study the performance of the beam-beam deflection based fast feedback system, for both e+e- and e-e- modes of operation. The beam-beam effects in the e-e- collisions make both the luminosity and the deflections more sensitive to offsets at the IP than in the case of the e+e- collisions. This reduces the performance of the feedback system in comparison to the standard e+e- collisions, and may require a different beam parameter optimization. | ||
| THPMN057 | New Concept for a CLIC Post-Collision Extraction Line | 2835 |
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Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", with contract number RIDS-011899. Strong beam-beam effects at the interaction point of a high-energy e+e- linear collider such as CLIC lead to an emittance growth for the outgoing beams, as well as to the production of beamstrahlung photons and e+e- coherent pairs. We present a conceptual design of the post-collision line for CLIC at 3 TeV, which separates the various components of the outgoing beam in a vertical magnetic chicane and then transports them to their respective dump. |
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| THPMN058 | Beam Dynamics Studies in the CLIC Injector Linac | 2838 |
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| The CLIC Injector Linac has to accelerate both electron and positron main beams from 200 MeV up to 2.42 GeV prior to their injection into the pre-damping rings. Its 26 accelerating structures operate at 1.875 GHz, with a loaded gradient of 17 MV/m. A FODO lattice that wraps the accelerating structures at the beginning of the linac, followed by a succession of triplet lattices between the accelerating structures, is proposed. The large transverse emittance (9200 mm.mrad), bunch length (5 mm) and energy spread (7 MeV) of the positron beam set constraints on the linac in order to reach acceptable characteristics at 2.42 GeV for the injection into the pre-damping ring. The use of a bunch compressor at the entrance of the linac is an option in order to achieve good performance in both the longitudinal and transverse phase spaces. Tracking studies of both electron and positron beams in the linac have been performed and are presented. | ||
| THPMN059 | Feedback Studies | 2841 |
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Funding: Supported by the European Community under the 6th Framework Programme "Structuring the European Research Area". Dynamic imperfections in future linear colliders can lead to a significant luminosity loss. We discuss different orbit feedback strategies in the main linac that can mitigate the emittance dilution and compare their efficiency. We also address the impact of ground motion in the beam delivery system and the potential cures. |
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| THPMN061 | Bunch Compressor for Beam-Based Alignment | 2844 |
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Funding: Supported by the European Community under the 6th Framework Programme "Structuring the European Research Area". Misalignments in the main linac of future linear colliders can lead to significant emittance growth. Beam-based alignment algorithms, such as Dispersion Free Steering (DFS), are necessary to mitigate these effects. We study how to use the Bunch Compressor to create the off-energy beams necessary for DFS and discuss the effectiveness of this method. |
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| THPMN062 | Dynamic Effects During Beam-Based Alignment | 2847 |
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Funding: Supported by the European Community under the 6th Framework Programme "Structuring the European Research Area". Complex beam-based alignment procedures are needed in future linear colliders to reduce the negative effects of static imperfections in the main linac on the beam emittance. The efficiency of these procedures could be affected by dynamic imperfections during their application. In this paper we study the resulting emittance growth. |
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| THPMN063 | CTF3 Combiner Ring Commissioning | 2850 |
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| CLIC Test Facility 3 (CTF3) has the objective to demonstrate the remaining feasibility issues of the CLIC two-beam technology for a future multi-TeV linear collider. One key issue is the efficient generation of a very high current 'drive beam' that serves as the power source for the acceleration of the main beam to high energy. This large current beam is produced by interleaving bunches in a combiner ring using transverse deflecting RF cavities. The 84 m long CTF3 combiner ring and the connecting transfer line have been recently installed and put into operation. The latest commissioning results will be presented. | ||
| THPMN064 | Luminosity Upgrade of CLIC-LHC ep/gp Collider | 2853 |
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| An energy-frontier or QCD-exploring ep and gp collider can be realized by colliding high-energy photons generated by Compton back-scattered off a CLIC electron beam, at either 75 GeV or 1.5 TeV, with protons or ions stored in the LHC. In this study we discuss a performance optimization of this type of collider by tailoring the parameters of both CLIC and LHC. An estimate of the ultimately achievable luminosity is given. | ||
| THPMN065 | Laser Collimation for Linear Colliders | 2856 |
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| We explore the possibility of laser-based postlinac beam collimation in future linear colliders. A laser employed as a spoiler can neither be 'destroyed' by the beam impact and nor generate collimator wake fields. In addition, the postlinac collimation section, presently the longest part of linear-collider beam delivery systems, can be shortened. In this paper, we investigate different types of laser modes for use as spoiler. Suitable laser beam parameters and modes are discussed for collimation in both CLIC and ILC. | ||
| THPMN068 | Beam Impact Studies on ILC Collimators | 2859 |
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Funding: CCLRC The Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts from each energetic electron or positron bunch of charged particles, in addition to maintaining low geometric and resistive wall wake fields. The transient shock wave resulting from rapid localised beam heating and its implications for spoiler design are studied using ANSYS. Shockwave propagation is modelled in 2 dimensions showing the effect of dilatational shockwaves striking free surfaces, producing reflected dilatational and distortional waves. The implication of these relflected waves on the damage of the collimators is also discussed. |
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| THPMN070 | Development of a Full Scale Superconducting Undulator Module for the ILC Positron Source | 2862 |
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. An undulator based positron source is a baseline for the International Linear Collider (ILC). The HeliCal collaboration in the UK is working on the development of a full scale 4-m long undulator module. Several prototypes have been built and tested in the R&D phase of the programme that culminated in the development of manufacturing techniques suitable for construction of the first full scale undulator sections. This paper details the design and the construction status of 4-m long undulator module. |
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| THPMN071 | Status of R&D on a Superconducting Helical Undulator for the ILC Positron Source | 2865 |
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. An undulator based positron source is a baseline for the International Linear Collider (ILC). The HeliCal collaboration in the UK is carrying out an R&D programme on a short period supercoducting helical undulator with the goal to develop manufacturing technique as well as modelling and measurement techniques. Several undulator prototypes have been built and successfully tested. This paper summarizes the results of the R&D phase of the project. |
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| THPMN072 | Material Damage Test for ILC Collimators | 2868 |
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| Simulations were completed to determine the energy deposition of an ILC bunch using FLUKA , Geant4 and EGS4 to a set of different spoiler designs. These shower simulations were used as inputs to thermal and mechanical studies using ANSYS. This paper presents different proposals to carry out a material damage test beam that would benchmark the energy deposition simulations and the ANSYS studies and give the researchers valuable data which will help achieve a definitive ILC spoiler design. | ||
| THPMN073 | Collimation Optimisation in the Beam Delivery System of the International Linear Collider | 2871 |
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| The collimation systems of the International Linear Collider (ILC) Beam Delivery System (BDS) must perform efficient removal of halo particles which lie outside the acceptable ranges of energy and spatial spread. An optimisation strategy based on earlier work is applied to the latest version of the BDS lattice. The resulting improvement in collimation performance is studied by halo tracking simulations, and the luminosity performance of the optimised lattice is also examined. | ||
| THPMN074 | The Status of the HeLiCal Contribution to the Polarised Positron Source for the International Linear Collider | 2874 |
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| The positron source for the International Linear Collider is a helical undulator-based design, which can generate unprecedented quantities of polarised positrons. The HeLiCal collaboration takes responsibility for the design and prototyping of the superconducting helical undulator, which is a highly demanding short period device with very small aperture, and also leads the start to end simulations of the polarised electrons and positrons to ensure that the high polarisation levels generated survive from the source up to the collision point. This paper will provide an update on the work of the collaboration, focusing on these two topic areas, and will also discuss future plans. | ||
| THPMN075 | Alignment Sensitivities in the ILC Damping Rings | 2877 |
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| For the International Linear Collider to reach its design luminosity, the damping rings must achieve a vertical emittance that is a factor of two below that achieved in any operating storage ring so far. Magnet alignment, orbit control and coupling correction are therefore critical issues for the ILC damping rings. We compare alignment sensitivities in some recent designs for the ILC damping ring lattices, and discuss the results of tuning simulations using different algorithms for correcting the vertical dispersion and the coupling. | ||
| THPMN076 | PAMELA - A Model for an FFAG based Hadron Therapy Machine | 2880 |
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| Approximately one third of the world?s 15000 accelerators are used for tumour therapy and other medical applications. Most of these are room temperature cyclotrons: a few are synchrotrons. Neither of these have ideal characteristics for a dedicated medical accelerator. The characteristics of FFAGs make them ideally suited to such applications, as the much smaller magnet size, greater compactness and variable energy offers considerable cost and operational benefits especially in a hospital setting. In the first stage the work on PAMELA will focus on the optimization of the FFAG design to deliver the specific machine parameters demanded by therapy applications. In this phase of the PAMELA project the effort will concentrate on the design of a semi-scaling type FFAGs to deliver a 450 MeV/u carbon ion beam, including detailed lattice and tracking studies. The second stage will use the existing expertise in the BASROC consortium to undertake a design of the magnets and RF system for PAMELA. An outline of the overall concept of PAMELA will be discussed and the actual status of the work will be presented. | ||
| THPMN077 | Improved 2mrad crossing angle layout for the International Linear Collider | 2883 |
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| The 2mrad interaction region and extraction line provide several machine and physics advantages, but also involves a number of technological challenges. In this paper a minimal extraction line without beam energy and polarization diagnostics is presented, which considerably simplifies the design and reduces costs. The optimization of the interaction region sextupoles, using current and proposed technologies, and an estimation of photon backscattering from spent beam particle losses are described. Overall performance is evaluated and compared with previous designs. The upgrade to 1 TeV and the possibility of including diagnostics are considered. | ||
| THPMN078 | The CONFORM Project: Construction of a NonScaling FFAG and its Applications | 2886 |
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| The CONFORM project, recently funded as part of the UK 'Basic Technology' initiative, will build a 20 MeV Non-Scaling FFAG (EMMA) at Daresbury. The experience gained will be used for the design of a proton machine (PAMELA) for medical research, and other applications for Non-Scaling FFAGs in different regimes will be explored. The successful development of this type of accelerator will provide many opportunities for increased exploitation, especially for hadron therapy for treatment of tumours, and the project provides a framework where machine builders will work with potential user communities to maximise the synergies and help this to happen successfully. | ||
| THPMN079 | Simulation of ILC Feedback BPM Signals in an Intense Background Environment | 2889 |
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. Experiment T-488 at SLAC, End Station A recorded distorted BPM voltage signals and an accurate simulation of these signals was performed. Geant simulations provided the energy and momentum spectrum of the incident spray and secondary emissions, and a method via image charges was used to convert particle momenta and number density into BPM stripline currents. Good agreement was achieved between simulated and measured signals. Further simulation of experiment T-488 with incident beam on axis and impinging on a thin radiator predicted minimal impact due to secondary emission. By extension to worst case conditions expected at the ILC, simulations showed that background hits on BPM striplines would have a negligible impact on the accuracy of beam position measurements and hence the operation of the FONT feedback system |
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| THPMN080 | Incoherent pair background processes with full polarizations at the ILC | 2892 |
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. Incoherent background pair production processes are studied with respect to full polarizations of all states. Real initial photon polarizations are obtained via a QED calculation of the beamstrahlung process. Virtual photon polarizations are related to the electric field of the colliding bunches at the point of pair production. An explicit expression for the virtual photon polarization vector is developed and found to have no circular polarization component. Pair polarization states are highly dependent on initial state circular polarization and are consequently produced almost unpolarized. The Breit-Wheeler cross-section with full polarizations is calculated and coded into the CAIN pair generator program. Numerical evaluations of the ILC operating in the seven proposed collider parameter sets shows that there are 10-20% less low energy pairs than previously thought. Collider luminosity as calculated by CAIN remains the same. |
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| THPMN081 | Measuring Single Particle Amplitudes with MICE | 2895 |
| The cooling of muons will be an essential element of a future neutrino factory. The Muon Ionization Cooling Experiment, MICE, to be built at RAL (UK) will be the first apparatus to demonstrate the feasibility of the ionisation cooling of muons. MICE will be unique in being able to make single-particle measurements. It will be possible to measure the amplitude of each muon in 6D phase space. We show how amplitude measurements can be used to quantify the transmission of the cooling channel and the increase in central phase space density due to cooling. | ||
| THPMN082 | Beam Injection Into EMMA Non-scaling FFAG | 2898 |
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| FFAG accelerators have been getting attention as promising candidates for the muon accelerators of a neutrino factory due to their large transverse acceptance and the capability of fast particle acceleration. Non-scaling FFAGs, which are a variation of FFAGs, are nowadays being intensively studied for their simple structure and operational flexibility. To demonstrate the technical feasibility of non-scaling FFAGs and to investigate their beam dynamics, a project to construct a small electron non-scaling FFAG (EMMA) has been proposed in the UK. In EMMA the injection and extraction energies must be arbitrarily changed for a beam with emittance of 3 mm to study the beam dynamics in detail for the entire range of operating energy. In addition, in the planned machine the betatron tunes vary more than a factor of two during acceleration. The requirement of variable injection or extraction energy requires careful optimisation of the of injection elements and operational conditions. The details and design status of the scheme will be described in this paper. | ||
| THPMN083 | Spin Tracking at the International Linear Collider | 2901 |
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. Polarized electron and positron beams are foreseen for the future International Linear Collider (ILC), with polarized electrons already included in the baseline design and polarized positrons seen as a highly-desirable upgrade. High precision physics requires the polarization of both beams to be known with a relative uncertainty of approximately 0.5% or better. Therefore all possible depolarization effects that could operate between the polarized sources and the interaction regions have to be carefully modelled. The "heLiCal" collaboration aims to provide a full "cradle-to-grave" analysis of all depolarization effects at the ILC, and to develop software tools to carry out appropriate computer simulations. In this paper we report on the first phase of our work which includes extensive simulations of the ILC spin-dynamics and a detailed study of beam-beam depolarization effects at the interaction point(s). |
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| THPMN085 | Proposed Dark Current Studies at the Argonne Wakefield Accelerator Facility | 2904 |
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Funding: US Department of Energy A study of breakdown mechanism has been initiated at the Argonne Wakefield Accelerator Facility (AWA). Breakdown may include several factors such as local field enhancement, explosive electron emission, Ohmic heating, tensile stress produced by electric field, and others. The AWA is building a dedicated facility to test various models for breakdown mechanisms and to determine the roles of different factors in the breakdown. An imaging system is being put together to identify single emitters on the cathode surface. This will allow us to study dark current properties in the gun. We also plan to trigger breakdown events with a high-powered laser at various wavelengths (IR to UV). Another experimental idea follows from the recent work on a Schottky-enabled photoemission in an RF photoinjector that allows us to determine in situ the field enhancement factor on a cathode surface. Monitoring the field enhancement factor before and after can shed some light on a modification of metal surface after the breakdown. |
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| THPMN086 | Metamaterial-loaded Waveguides for Accelerator Applications | 2906 |
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Funding: US Department of Energy National Science Foundation grant # 0237162 Metamaterials (MTM) are artificial periodic structures made of small elements and designed to obtain specific electromagnetic properties. As long as the periodicity and the size of the elements are much smaller than the wavelength of interest, an artificial structure can be described by a permittivity and permeability, just like natural materials. Metamaterials can be customized to have the permittivity and permeability desired for a particular application. Waveguides loaded with metamaterials are of interest because the metamaterials can change the dispersion relation of the waveguide significantly. Slow backward waves, for example, can be produced in a LHM-loaded waveguide without corrugations. In this paper we present theoretical studies and computer modeling of waveguides loaded with 2D anisotropic metamaterials, including the dispersion relation for a MTM-loaded waveguide. The dispersion relation of a MTM-loaded waveguide has several interesting frequency bands which are described. It is shown theoretically that dipole mode suppression may be possible. Therefore, metamaterials can be used to suppress wakefields in accelerating structures. |
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| THPMN087 | Simulations of the Rotating Positron Target in the Presence of OMD Field | 2909 |
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Funding: US Department of Energy For an ILC undulator-based positron source target configuration, a strong optical matching device (OMD) field is needed inside the target to increase the positron yield (by more than 40%)[1]. It is also required that the positron target is constantly rotated to reduce thermal and radiation damage. We report on a simulation of the rotating metal target wheel under a strong magnetic field. By rearranging Maxwell?s equations for a rotating frame and using FEMLAB, we have solved the detailed magnetic field distribution and eddy current of a rotating metal disk in magnetic field, and so the required power to drive the target wheel. In order to validate the simulation process, we have compared our results with previous experimental data [2] and found they are in very good agreement, but differ from previous approximate models [3]. Here we give detailed results on the proposed ILC target system, such as induced magnetic field (dipole and higher orders), eddy current distribution and the driving force requirements. The effect of these higher order fields on the positron beam dynamics is also considered. |
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| THPMN088 | C-Band High Power RF Generation and Extraction Using a Dielectric Loaded Waveguide | 2912 |
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Funding: Department of Energy
We report on the fabrication, simulation, and high-power testing of a C-band RF power extractor recently conducted at the Argonne Wakefield Accelerator (AWA) facility. Dielectric loaded accelerating (DLA) structures can be used for high-power RF generation [*,**] when a high-current electron beam passes through a DLA structure and loses energy into the modes of the structure due to self-wakefields. The AWA generates high charge (up to 100nC), short bunch length (1.5mm~2.5mm) electron beams, which is ideal for high-power RF generation. The generated RF power can be subsequently extracted with a properly designed extraction coupler in order to accelerate a second beam, or for other high power purposes. In this paper, the detailed design of a 7.8 GHz DLA power extractor, MAFIA simulations, and results of the high-power test are presented. Simulation predictions of an 79 MW, 2.2 ns long RF pulse (generated by a single 100 nC electron bunch) and a longer RF pulse of the same power (obtained from a 35 nC periodic bunch train) will be compared to experimental results.
* W. Gai, et al, Experimental Demonstration of Two Beam Acceleration Using Dielectric Step-up Transformer, PAC01, pp.1880-1882.** D. Yu, et al, 21GHz Ceramic RF Power Extractor, AAC02, pp.484-505. |
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| THPMN089 | Enhancement of Heat Removal using Concave Liquid Metal Targets for High-Power Accelerators | 2915 |
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| The need is increasing for development of high power targets and beam dump areas for the production of intense beams of secondary particles (IFMIF, SNS, RIA, LHC). The severe constraints arising from a MW beam power deposited on targets and absorbers, call for non-trivial procedures to dilute the beam. This study describes the development of targets and absorbers and the advantages of using flowing liquid metal in concave channels first proposed by IFMIF to raise the liquid metal boiling point by increasing the pressure in liquid supported by a centrifugal force. Such flow with a back-wall is subject to the Taylor-Couette instability. The instability can play a positive role of increasing the heat transfer from the hottest region in the target/absorber to the back-wall cooled by water. At the laminar stage of the instability with a certain wave number of vortexes, the heat transfer from a chain of vortexes to the wall increases heat removal by enhancing the convective transport inside the liquid bulk and from the bulk to the wall. Results of theoretical analysis and numerical modeling of both targets and dump areas for the IFMIF, ILC, and RIA facilities are presented. | ||
| THPMN090 | Systematic Study of Undulator Based ILC Positron Source: Production and Capture | 2918 |
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| A systematic study of the positron production and capture systems for the undulator-based ILC positron source has been performed. Various undulator parameters, such as k and λ, were considered. Our model starts from the electron beam production of the polarized photons in the undulator section, photon transport and collimation in the drift section, and photon interaction on the target (titanium or tungsten). Next, our model transports the produced polarized positrons from the target, through the tapered capturing magnet, and through the normal conducting linac to several hundred MeV. Finally, the captured positrons meeting the damping ring emittance and energy spread requirements are accelerated up to 5 GeV using the standard ILC superconducting cavities. We will present parametric studies for the different scenarios (e.g. 60% polarization vs. unpolarized; target immersed in magnetic field vs. non-immersed) currently under consideration and report on the capturing yield and polarizations achieved for each. | ||
| THPMN091 | Study on High Flux Accelerator Based Slow Positrons Source | 2921 |
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| This work represents a new direction in the development of linac-based high intense slow positron source. The approach is to use RF cavities to decelerate positrons (to ~100 keV) which are produced from a high-energy electron (~10 MeV) beam irradiating a heavy-metal target. In this paper, we present simulation works on the technique to decelerate the positrons to energies where techniques such as penning traps, DC deceleration or moderation can be done with high efficiency. Present techniques for decelerating positrons by thermalizing them in tungsten moderator have an efficiency of 10-3 to 10-5 slow positrons per high energy positron, so even modest success in decelerating and trapping positrons can lead to an increase in the production of low-energy positrons. The challenging aspect of this work is the broad energy and angular distribution of the positrons produced by pair-production in the heavy-metal target. We have explored the use of an adiabatic-matching device and a pillbox RF cavity and have obtained promising results. | ||
| THPMN092 | Design and Prototyping of the AMD for the ILC | 2924 |
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The Adiabatic Matching Device (AMD), a tapered magnetic field with initial on-axis magnetic field up to 5 Tesla, is required in ILC positron capturing optics. An option of using a pulsed normal conducting structure based on flux concentrator technique can be used to generate high magnetic field*. By choosing the AMD geometry appropriately, one can shape the on-axis magnetic field profile by varying the inner shape of a flux concentrator. In this paper, we present an equivalent circuit model of a pulsed flux concentrator based on frequency domain analysis. The analysis shows a very good agreement with the experiment results from reference*. We have also constructed a prototype flux concentrator based on the circuit model, and experimental results are presented to verify the effectiveness of the model. Using the equivalent circuit model, a flux concentrator based AMD is designed for ILC positron matching. The beam capturing simulation results using the designed AMD are presented in this paper.
* H. Brechna, D. A. Hill and B. M. Bally, "150 KOe Liquid Nitrogen Cooled Flux Concentrator Magnet", Rev. Sci. Instr., 36 1529,1965. |
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| THPMN094 | Simulations of Parametric-resonance Ionization Cooling | 2927 |
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Funding: Supported in part by DOE SBIR grant DE-FG02-04ER84016 Parametric-resonance ionization cooling (PIC) is a muon-cooling technique that is useful for low-emittance muon colliders. This method requires a well-tuned focusing channel that is free of chromatic and spherical aberrations. In order to be of practical use in a muon collider, it also necessary that the focusing channel be as short as possible to minimize muon loss due to decay. G4Beamline numerical simulations are presented of a compact PIC focusing channel in which spherical aberrations are minimized by using design symmetry. |
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| THPMN095 | Muon Bunch Coalescing | 2930 |
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Funding: Supported in part by DOE STTR grants DE-FG02-04ER86191 and -05ER86253. The idea of coalescing multiple muon bunches at high energy to enhance the luminosity of a muon collider provides many advantages. It circumvents space-charge, beam loading, and wakefield problems of intense low-energy bunches while restoring the synergy between muon colliders and neutrino factories based on muon storage rings. A sampling of initial conceptual design work for a coalescing ring is presented here. |
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| THPMN096 | Stopping Muon Beams | 2933 |
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Funding: Supported in part by DOE SBIR/STTR grant DE-FG02-03ER83722 The study of rare processes using stopping muon beams provides access to new physics that cannot be addressed at energy frontier machines. The flux of muons into a small stopping target is limited by the kinematics of the production process and by stochastic processes in the material used to slow the particles. Innovative muon beam cooling techniques are being applied to the design of stopping muon beams in order to increase the event rates in such experiments. Such intense stopping beams will also aid the development of applications such as muon spin resonance and muon-catalyzed fusion. |
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| THPMN097 | Envelope and Multi-slit Emittance Measurements at Fermilab A0-Photoinjector and Comparison with Simulations | 2936 |
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Funding: Operated by Universities Research Association, Inc. for the U. S. Department of Energy under contract DE-AC02-76CH03000. Recently we have measured the transverse emittance using both multi-screen as well as muli-slit methods for a range of electron beam intensities from 1 nC to 4 nC at A0 Photoinjector facility at Fermilab. The data have been taken with un-stacked 2.5 ps laser pulse. In this paper we report on these measurements and compare the results with the predictions from beam dynamics calculations using ASTRA and General Particle Tracer including 3D space charge effects. |
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| THPMN098 | Modeling and Design of the ILC Test Area Beam Absorbers at Fermilab | 2939 |
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| Detailed MARS15 simulations have been performed on energy deposition and shielding of the proposed ILC Test Area absorbers to deal with up to 50 kW of 800 MeV electron beam power and provide unlimited occupancy conditions in the hall. ANSYS analysis based on the calculated energy deposition maps confirms robustness of the proposed design of the absorbers and beam windows for normal operation and for various failure modes. A non-trivial shielding solution was found for the entire region housing the main and single-bunch absorbers. | ||
| THPMN099 | Plans for a 750 MeV Electron Beam Test Facility at Fermilab | 2942 |
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| A 750 MeV electron beam test facility at Fermilab is in the planning and early construction phase. An existing building is being converted for this facility. The photoinjector currently in use at the Fermilab NICADD Photoinjector Laboratory (FNPL) will be moved to the new facility and upgraded to serve as an injector for a beam acceleration section consisting of 3 Tesla or ILC-type cryomodules. A low energy off-axis beam will be constructed to test ILC crab cavity designs and provide opportunities for other tests. Downstream beamlines will consist of a diagnostic section, a beam test area for additional beam experiments, and a high power beam dump. The initial program for this facility will concentrate on testing ILC-type cryomodules and RF control with full ILC beam intensity. A future building expansion will open up further possibiliities for beam physics and beam technology experiments. | ||
| THPMN100 | Suppression of Muon Backgrounds Generated in the ILC Beam Delivery System | 2945 |
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| Particle fluxes generated from the interactions of beam halo with the collimators in the ILC Beam Delivery System (BDS) can exceed tolerable levels for the collider detectors and create hostile radiation environment in the interaction region. Thorough analysis of the BDS model, beam loss patterns, driving geometry factors and physics processes along with verification of the simulation codes were performed for the current ILC BDS layout with 250-GeV electron and positron beams crossing at 14 mrad with a push-pull detector option. Muon flux reduction by distributed toroids (doughnut-type spoilers) in comparison with magnetic iron walls filling the BDS tunnel are calculated and analysed in great detail. Shielding conditions which allow occupancy of the interaction region while the full power beam is on the linac tuneup dump are also studied. | ||
| THPMN102 | A Muon Beam for Cooling Experiments | 2948 |
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Funding: Work supported by the US Department of Energy Within the framework of the Fermilab Muon Collider Task Force, the possibility of developing a dedicated muon test beam for cooling experiments has been investigated. Cooling experiments can be performed in a very low intensity muon beam by tracking single particles through the cooling device. With sufficient muon intensity and large enough cooling decrement, a cooling demonstration experiment may also be performed without resolving single particle trajectories, but rather by measuring the average size and position of the beam. This allows simpler, and thus cheaper, detectors and readout electronics to be used. This paper discusses muon production using 400MeV protons from the linac, decay channel and beamline design, as well as the instrumentation required for such an experiment, in particular as applied to testing the Helical Cooling Channel (HCC) proposed by Muons Inc. |
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| THPMN103 | New Nonscaling FFAG for Medical Applications | 2951 |
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Funding: Work supported by by the Fermilab Research Association, Inc., under contract DE-AC02-76CH00300 with the U. S. Department of Energy. Fixed Field Alternating Gradient (FFAG) machines have been the subject of recent international activity due to their potential for medical applications and accelerator-based technologies. In particular, nonscaling FFAGs (where the optics are not constant and therefore do not scale with momentum) stand to offer the high current advantage of the cyclotron combined with the smaller radial aperture of the synchrotron plus variable extraction energy. Here, a hybrid design for a nonscaling FFAG accelerator has been invented which uses both edge and alternating-gradient focusing principles applied to a combined-function magnet applied in a specific configuration to stabilize tunes through an acceleration cycle which extends over a factor of 2-6 in momentum. Using normal conducting magnets, the final, extracted energy from this machine attains 400 MeV/nucleon and a normalized emittance of ~10 - 20π, and thus supports a carbon ion beam in the energy range of interest for cancer therapy. |
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| THPMN104 | Recent Studies of Dispersion Matched Steering for the ILC Bunch Compressor and Main Linac | 2954 |
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| Beam Based Alignment techniques are expected to play a critical role to the emittance preservation for the ILC. The Dispersion Free Steering (DFS) method is studied in detail in the 2nd statge of the bunch Compressor and in the beginning of the curved Main Linac. It is shown than in absence of cavity tilts (rotations on the YZ plane), DMS provides a unique and stable solution with negligible emittance growth. If cavity tilts are about 200 to 300 micro-radiant, the DMS solution is no longer unique and significant emittance occurs as well. While within the ILC budget, other dynamical effects, such a large beam jitter or sudden ground motion will cause severe performance degradation. A Variant of the DFS algorithm can be used to re-aling cavity supports, leading to better LET performance. In presence of perturbations (klystron jitter, ground motion,.. ) such DFS solutions are easier to maintain and improved if they are stable and unique. Therefore, it is suggested to consider using movers on quadrupole/BPM and, a bit more controversial, for the support system of the r.f. cavities, especially at low energy, where spurious dispersion due to cavity tilts are large. | ||
| THPMN106 | Use of Harmonics in RF Cavities in Muon Capture for a Neutrino Factory or Muon Collider | 2957 |
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Funding: Supported in part by DOE STTR grant DE-FG02-05ER86252 Common to various front end designs for a muon collider or neutrino factory are costly low frequency RF cavities used to bunch muons. In this paper we show that adding higher harmonic RF cavities to the bunching section of a muon capture channel can provide as good or better bunching efficiency than the case where only the fundamental is used. Since higher harmonic cavities are less expensive to build and operate, this approach implies significant cost savings. |
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| THPMN107 | Study of Emittance Bumps in The ILC Main Linac | 2960 |
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Funding: U. S. Department of Energy This paper reports the studies of using global emittance tuning bumps to limit the emittance growth to very small values in the main linac of the proposed International Linear Collider (ILC) machine. Simulation studies indicate that closed-orbit emittance bumps, when used after local or quasi-local beam based alignment techniques, can be utilized to further suppress the emittance growth in the ILC main linac. A series of simulations are performed to find the optimal number of bumps and their locations. A more general method of optimizing the emittance bumps in the ILC main linac is also discussed. |
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| THPMN108 | Study of Adaptive Alignment as Beam Based Alignment in ILC Main Linac in the Presence of Ground Motion | 2963 |
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Funding: U. S. Department of Energy The proposed International Linear Collider (ILC) machine requires extremely small transverse emittances of the beam to achieve desired luminosity. A very precise alignment of the beamline elements, both in main linac and in beam delivery system, is required to limit the emittance growth. However, ground motion (GM) and technical noise continuously misaligns the elements and hence spoils the effect of alignment. It is thus very important to understand and analyze the effect of GM on the performance of ILC. Also, it is imperative to find an effective dynamic alignment procedure to preserve the transverse emittances in the presence of GM. In this paper we study the effect of GM and technical noise on the proposed ILC main linac. Initial alignment of the Linac is performed through one-to-one and dispersion free steering (DFS). We then study "Adaptive Alignment" method to mitigate the effects of GM and technical noise. |
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| THPMN109 | Status of the ILC Main Linac Lattice Design | 2966 |
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| The report describes the present design of the ILC Main Linac lattice. The topics covered include basic element layout, optical functions, and issues centered around the linac following of the Earth's curvature. Also discussed are beam parameter measurements and instrumentation requirements. | ||
| THPMN110 | The MANX Muon Cooling Demonstration Experiment | 2969 |
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Funding: Supported in part by DOE STTR grant DE-FG02-06ER86282 MANX is an experiment to prove that effective six-dimensional (6D) muon beam cooling can be achieved a Helical Cooling Channel (HCC) using ionization-cooling with helical and solenoidal magnets in a novel configuration. The aim is to demonstrate that 6D muon beam cooling is understood well enough to plan intense neutrino factories and high-luminosity muon colliders. The experiment consists of the HCC magnets that envelop a liquid helium energy absorber, upstream and downstream instrumentation to measure the particle or beam parameters before and after cooling, and emittance matching sections between the detectors and the HCC. We describe and compare the experimental configuration for both single particle and beam profile measurement techniques based on G4Beamline simulations. |
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| THPMN111 | A Kicker Driver for the International Linear Collider | 2972 |
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| Diversified Technologies, Inc. (DTI), under a SBIR grant from the U. S. Department of Energy, is developing a driver for a kicker strip-line deflector which inserts and extracts charge bunches to and from the electron and positron damping rings of the International Linear Collider. The deflector requires a driver capable of 10 kV, 200 A pulses of 2 ns duration, after-pulse clamping of the deflector voltage to less than one volt within six nanoseconds, and must function at burst rates of 3 to 6 MHz. The driver must also effectively absorb high-order mode signals emerging from the deflector itself. In this paper, DTI will describe a promising approach to the design of the kicker driver involving high voltage DSRDs (Drift Step Recovery Diodes) and high voltage MOSFETs. In addition, our design approach to meeting the challenges posed by the ILC requirements will be discussed. | ||
| THPMN112 | Colliding Pulse Injection Experiments in Non-Collinear Geometry for Controlled Laser Plasma Wakefield Acceleration of Electrons | 2975 |
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Funding: Supported by DOE grant DE-AC02-05CH11231, DARPA, and and INCITE computational grant.
Colliding laser pulses* have been proposed as a method for controlling injection of electrons into a laser wakefield accelerator (LWFA) and hence producing high quality relativistic electron beams with energy spread below 1% and normalized emittances below 1 micron. The original proposal relied on three coaxial pulsesI. One pulse excites a plasma wake, and a collinear pulse following behind it collides with a counterpropagating pulse forming a beat pattern that boosts background electrons into accelerating phase. A variation of this method uses only two laser pulses** which may be non-collinear. The first pulse drives the wake, and beating of the trailing edge of this pulse with the colliding pulse injects electrons. Non-collinear injection avoids optical elements on the electron beam path (avoiding emittance growth). We report on progress of non-collinear experiments at LBNL, using the Ti:Sapphire laser at the LOASIS facility of LBNL. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiment will be presented.
* E. Esarey, et al, Phys. Rev. Lett 79, 2682 (1997).** G. Fubiani, Phys. Rev. E 70, 016402 (2004). |
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| THPMN113 | Performance of Capillary Discharge Guided Laser Plasma Wakefield Accelerator | 2978 |
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Funding: This work is supported by US DoE office of High Energy Physics under contract DE-AC02-05CH11231 and DARPA. A GeV-class laser-driven plasma-based wakefield accelerator has been realized at the Lawrence Berkeley National Laboratory (LBNL). The device consists of a 100 TW-class high repetition rate Ti:sapphire LOASIS laser system of LBNL and a gas-filled capillary discharge waveguide developed at Oxford University. Results will be presented on the generation of GeV-class electron beams with a 3.3 cm long preformed plasma channel. The use of a discharge-based waveguide permitted operation at an order of magnitude lower density and 15 times longer distance than in previous experiments that relied on laser-preformed plasma channels. Laser pulses with peak power ranging from 10-50 TW were guided over more than 20 Rayleigh ranges and high-quality electron beams with energy up to 1 GeV were obtained. The dependence of the electron beam characteristics on plasma channel properties and laser parameters are discussed. |
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| THPMN114 | Recent Progress at LBNL on Characterization of Laser Wakefield Accelerated Electron Bunches Using Coherent Transition Radiation | 2981 |
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Funding: Work supported by US DoE Office of High Energy Physics under contract DE-AC03-76SF0098 and DARPA.
At LBNL, laser wakefield accelerators (LWFA) now produce ultra-short electron bunches with energies up to 1 GeV[1]. As femtosecond electron bunches exit the plasma they radiate a strong burst in the terahertz range[2,3], via coherent transition radiation (CTR). Measuring the CTR properties allows non-invasive bunch-length diagnostics[4], a key to continuing rapid advance in LWFA technology. In addition, this method of CTR generation provides very high peak power that can lead novel THz-based applications. Experimental bunch length characterizations through electro-optic sampling as well as bolometric analysis are presented. Measurements demonstrate both the shot-by-shot stability of bunch parameters, and femtosecond synchronization between bunch, THz pulse, and laser beam.
[1] W. P. Leemans et al., Nature Physics 2, 696(2006)[2] W. P. Leemans et al., PRL 91, 074802(2003)[3] C. B. Schroeder et al., PRE 69, 016501(2004)[4] J. van Tilborg et al., PRL 96, 014801(2006) |
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| THPMN115 | Injection and Extraction Lines for the ILC Damping Rings | 2984 |
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Funding: This work was supported by the U. S. Department of Energy under Contract No. DE-AC02-05CH11231. The current design for the injection and extraction lines into and out of the ILC Damping Rings is presented as well as the design for the abort line. Due to changes of the geometric boundary conditions by other subsystems of the ILC a modular approach has been used to be able to respond to recurring layout changes while reusing previously designed parts. Available beam dynamics studies for those lines are discussed. |
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| THPMN116 | Frequency Map Studies for the ILC Damping Rings | 2987 |
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Funding: This work was supported by the U. S. Department of Energy under Contract No. DE-AC02-05CH11231. Designing a lattice with sufficient dynamic aperture for the ILC Damping Rings is very challenging as the lattice needs to provide a small equilibrium emittance and at the same time a large aperture for the injected beam including a large momentum acceptance. In addition outside constraints have forced layout changes in the damping ring. Some of the layout changes had an impact on the dynamic aperture. In order to better understand the changes in dynamic aperture, frequency maps are studied. Those studies can help in identifying the reason for the changed dynamic aperture and in finding a good location for the betatron tunes and determining an upper limit for the chromaticities. A summary of recent studies and suggestions improving the dynamic aperture by choosing a different tune are presented. |
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| THPMN117 | Design of a VHF-band RF Photoinjector with MegaHertz Beam Repetition Rate | 2990 |
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Funding: This work is supported by the Director, Office of Science, High Energy Physics, U. S. Dept. of Energy under Contract no. DE-AC02-05CH1121 New generation accelerator-based X-ray light sources require high quality beams with high average brightness. Normal conducting L- and S-band photoinjectors are limited in repetition rate and D-C (photo)injectors are limited in field strength at the cathode. We propose a low frequency normal-conducting cavity, operating at 50 to 100 MHz CW, to provide beam bunches at a rate of one MegaHertz or more. The photoinjector uses a re-entrant cavity structure, requiring less than 100 kW CW, with a peak wall power density less than 10 W/cm2. The cavity will support a vacuum down to 10 picoTorr, with a load-lock mechanism for easy replacement of photocathodes. The photocathode can be embedded in a magnetic field to provide correlations useful for flat beam generation. Beam dynamics simulations indicate that normalized emittances on the order of 1 mm-mrad are possible with gap voltage of 750 kV, with fields up to 20 MV/m at the photocathode, for 1 nanocoulomb charge per bunch after acceleration and emittance compensation. Long-bunch operation (10's of picosecond) is made possible by the low cavity frequency, permitting low bunch current at the 750 kV gap voltage. |
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| THPMN118 | Modelling of E-cloud Build-up in Grooved Vacuum Chambers Using POSINST | 2993 |
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Funding: Work supported by DOE contract No. DE-AC02-05CH11231 Electron cloud build-up and related beam instabilities are a serious concern for the positron damping ring of the International Linear Collider (ILC). To mitigate the effect use of grooved vacuum-chamber walls is being actively investigated in addition to more conventional techniques like surface coating, scrubbing, and/or conditioning. Experimental and simulation studies have characterized the effectiveness of the grooved surface by means of an effective secondary emission yield (SEY), which has been measured to be significantly lower than the SEY of a smooth surface of the same material. However, some inconsistencies of the results, and the need to model the experimental testing of the grooved surface concept in more detail, have motivated us to simulate the grooved surfaces directly. Specifically, we have augmented the code POSINST by adding the option to simulate the electron-cloud build-up in the presence of a grooved surface geometry. By computing the accumulated e-cloud density and comparing it with the same quantity computed for a smooth surface, we infer an effective SEY, and we thereby make contact with the effective SEY estimates obtained from previous studies. |
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| THPMN119 | Status of the International Muon Ionization Cooling Experiment (MICE) | 2996 |
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Funding: Work supported by U. S. Dept. of Energy, Office of High Energy Physics, under contract no. DE-AC02-05CH11231.
An international experiment to demonstrate muon ionization cooling is scheduled for beam at Rutherford Appleton Laboratory in 2007. The experiment comprises one cell of the Study II cooling channel*, along with upstream and downstream detectors to identify individual muons and measure their initial and final 6D phase-space parameters to a precision of 0.1%. Magnetic design of the beam line and cooling channel are complete and portions are under construction. The experiment will be described, including hardware designs, fabrication status, and running plans. Phase 1 of the experiment will prepare the beam line and provide detector systems, including time-of-flight, Cherenkov, scintillating-fiber trackers and the spectrometer solenoids, and an electromagnetic calorimeter. The Phase 2 system will add the cooling channel components, including liquid-hydrogen absorbers embedded in superconducting focus solenoids, 201-MHz normal-conducting RF cavities, and their surrounding coupling coil solenoids. The MICE Collaboration goal is to complete the experiment by 2010; progress toward this goal will be indicated. The supporting R&D program and its present results will also be described.
*S. Ozaki, R. Palmer, M. Zisman, and J. Gallardo (eds.), "Feasibility Study II of a Muon-based Neutrino Source," BNL-52623, 2001; http://www.cap.bnl.gov/mumu/studyii/final_draft/The-Report.pdf. |