NIRS, Chiba-shi
AEC, Chiba
Tumor therapy using energetic carbon ions, as provided by the HIMAC, has been performed since June 1994, and more than 5000 patients were treated until now. With the successful clinical results over more than ten years, we are constructing a new treatment facility. The new facility would have three treatment rooms; two of them have both horizontal and vertical fixed-irradiation-ports, and the other has a rotating-gantry-port. For all the ports, a scanning irradiation method is applied. The new facility is constructed in conjunction with the HIMAC, and heavy-ion beams will be provided by the HIMAC accelerators. To fulfill requirements for the scanning irradiation, we proposed multiple-energy operation with the quasi-DC extension of a flat top. With this operation, the beam energy can be successively varied within a single synchrotron-cycle, and therefore no energy degrader or the range shifter is required. The beam acceleration and extraction tests of the multiple-energy operation were successfully made. We will present the development of this operation as well as results of the beam acceleration tests.
JAI, Oxford
Accelerator physics is often viewed as a difficult subject to communicate to schools and the public. The "Accelerate!" project, initiated in the UK in 2008, engages audiences with accelerator physics through a 45-minute live, interactive demonstration show, using basic physics demonstrations to explain the physics of particle accelerators and what they are used for. Feedback has been overwhelmingly positive from all areas, and demand for the show is very high, with over 3000 students involved in the first year of running. The program is also contributing to the science communication skills of physics graduate students. I discuss how to portray basic accelerator concepts through easy to access demonstrations and initial results of audience evaluation of the show.
Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto
A liquid cluster ion beam irradiation system has been developed for surface processing and modification of solid materials used in the semiconductor industry. The liquid clusters are produced by the adiabatic expansion method. The vapor pressure of the source materials such as water or ethanol is increased by heating, and ejected to a vacuum chamber through a supersonic nozzle. The ionized clusters by the electron impact ionization are accelerated to typically 3-9 kV after the elimination of monomers by the retarding voltage method, and irradiated on the solid surfaces. The sputtering yield of silicon by the ethanol cluster ion beam irradiation was more than 100 times larger than that by an argon monomer ion beam. On the other hand, the radiation damage and surface roughness caused by the ethanol cluster ion beam irradiation decreased when the mean cluster size was increased by increasing the retarding voltage. Irradiation effects of liquid cluster ion beams on polymers are also discussed.
RLNR, Tokyo
AIST, Tsukuba, Ibaraki
WERC, Tsuruga , Fukui
Positron that is the antiparticle of the electron, by the specific character, can evaluate vacant spaces in microstructure from atomic level to nanometer level, which is difficult in other measurement methods. In the case of high functional material, this structure often relates directly to the performance, and the evaluation method that uses the positron beam is expected as a useful measurement tool to develop a new material. If it is able to produce more high-intense and low-energy positron beam with an accelerator, the microstructure evaluation is carried out in prompt and high accuracy for various demands of the material analysis. We have studied a positron production system using a superconducting electron linac instead of normal conducting one. Electron beam accelerated with the superconducting linac is irradiated on tantalum and converted to bremstrahlung photons, and positron beam is produced by pair creation of them. The designed acceleration energy of the superconducting electron linac is 15-40 MeV and the maximum beam power is 10 kW. The system configuration and the progress status will be presented.
KURRI, Osaka
University of Fukui, Faculty of Engineering, Fukui
In Kyoto University Research Reactor Institute (KURRI), The FFAG accelerator complex for accelerator driven sub-critical reactor (ADSR) project has been already constructed and world first ADSR experiment has been done at May, 2009. In the main ring, proton beams of 11.5 MeV are injected and accelerated up to 100 MeV. During the acceleration, two different types of beam loss have been observed. To investigate these beam loss, betatron and synchrotron motion have been measured experimentally. The details of measurements will be described in this presentation.
JAEA/Kansai, Kyoto
Intense laser pulse is utilized to generate compact sources of electrons, ions, x-rays, neutrons. Recently, high energy negative ions are also observed in experiments using cluster or gas target*. To explain the acceleration of negative ions from laser-generated plasmas, we proposed Coulomb implosion mechanism**. When clusters or underdense plasmas are irradiated by an intense laser pulse, positive ions are accelerated inside the clusters or in the self-focusing channel by the Coulomb explosion. This could lead to the acceleration of negative ions towards target center. The maximum energy of negative ions is typically several times lower than that of positive ions. A theoretical description and corresponding Particle-in-Cell simulations of Coulomb implosion mechanism are presented. We show the evidence of the negative ion acceleration observed in our experiments using high intensity laser pulse and the cluster-gas targets.
* S.Ter-Avetisyan et al., J. Phys. B 37 (2004) 3633.
** T.Nakamura et al., Phys. Plasmas 16 (2009) 113106.
KEK, Ibaraki
MELCO SC, Tsukuba
J-PARC, KEK & JAEA, Ibaraki-ken
Efforts have been made to reduce the magnetic field ripple of the bending, quadrupole and sextupole magnets of the J-PARC main ring using the trim coils of the magnets. The quadrupole magnet has 24 turn main coil and 11 turn trim coil per pole those can be considered as a primary winding and a secondary winding of a transformer. When the trim coil is shorted, the induced trim coil current cancels the field ripple. The field ripple of the quadrupole magnet was reduced by a factor of 6 by shorting trim coil. The trim coil current, however, deforms the acceleration field pattern if the coil is shorted all the time of the current pattern of flat bottom, acceleration, flat top and recovery. The MOSFET relay was used to short the coil and to reduce the field ripple during the flat bottom and flat top. The circuits were built for the quadrupole and sextupole magnets. The plan has been made to wind optimized trim coils for the bending magnets.
CERN, Geneva
National Technical University of Athens, Athens
We study the interaction of macro-particles residing inside the LHC vacuum chamber, e.g. soot or thermal-insulation fragments, with the circulating LHC proton beam. The coupled equations governing the motion and charging rate of metallic or dielectric micron-size macro-particles are solved numerically to determine the time spent by such "dust" particles close to the path of the beam as well as the resulting proton-beam losses, which could lead to a quench of superconducting magnets and, thereby, to a premature beam abort.
BNL, Upton, Long Island, New York
During the acceleration process, heavy ion beams in RHIC cross the transition energy. When RHIC was colliding deuterons and gold ions during Run-8, lattices with different integer tunes were used for the two rings. This resulted in the two rings crossing transition at different times, which proved beneficial for the "Yellow" ring, the RF system of which is slaved to the "Blue" ring. For the symmetric gold-gold run in FY2010, lattices with different transition energies but equal tunes were implemented. We report the optics design concept as well as operational experience with this configuration.
RCNP, Osaka
An upgrade program of the RCNP cyclotron facility for increase of beam intensity and improvement of beam quality is in progress to meet requirements from research in nuclear physics and industrial applications using secondarily produced particles such as neutrons, muons and radioisotopes. A 2.45 GHz ECR ion source using a set of permanent magnets was developed for high intensity proton beam production. The proton beam intensity more than 0.5 mA at an extraction energy of 15 keV has been obtained with a proton ratio more than 80 %. The quality of the pre-accelerated beam from the K140 injector AVF cyclotron has been improved by a flat-top(FT) acceleration system to enhance the beam transmission to the K400 ring cyclotron. Transversal resonant mode of a dee electrode with a span angle of 180 degrees was investigated to achieve the FT acceleration in the frequency region from 50 to 60 MHz. In this paper, developments for high intensity proton beam acceleration and beam quality improvement using the FT acceleration system of the AVF cyclotron will be mainly presented.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
JAI, Oxford
A novel nonlinear, nonscaling FFAG ring has been designed for proton and ion acceleration [1]. It can be used for proton and carbon therapy as well as a proton driver for various facilities such as a high intensity neutrino factory. The machine has novel features including variable energy extraction and a high repetition rate of about 1 kHz. Taking as an example the PAMELA proton ring, under study at the John Adams Institute in Oxford, we present results of an error study. A calculation of alignment tolerance is made, in which the effects of translational misalignments of the triplet magnets are included. The effect of misalignments on the dynamic aperture of the machine is investigated.
[1] S. L. Sheehy, K. J. Peach, H. Witte, D. J. Kelliher and S. Machida, Phys. Rev. ST Accel. Beams, 13 (2010) 040101
KEK, Ibaraki
Nagaoka University of Technology, Nagaoka, Niigata
New acceleration system using an induction cell has been developed at KEK by using KEK 12-GeV PS*. We call an accelerator using the induction acceleration system "Digital Accelerator". The PS-Booster is now being renovated as the first Digital Accelerator (DA) by introducing the induction acceleration instead of rf**. Argon ion beam from the ECR ion source is injected to the DA by an electrostatic beam kicker. Another electrostatic device with the same structure is used for chopping the beam before injection. The accelerated beam is extracted by the existing extraction system, which comprises bump, septum and kicker magnets. Since these magnets are installed in a vacuum chamber, vacuum pressure deteriorates due to outgas from them. In order to reduce a beam loss in the DA ring, the pressure level is crucial especially for an ion beam. Therefore, we decided to put the septum magnet outside the vacuum chamber and insert a vacuum duct in the gap, since it dominantly contributes to the vacuum pressure more than the other magnets. This paper describes the electrostatic beam chopper, injection kicker and septum magnet containing the vacuum duct for the KEK DA and beam dynamics.
*K. Takayama, Phys. Rev. Lett. 98, 054801 (2007)
**K. Takayama, "KEK Digital Accelerator for Material and Biological Sciences", T. Iwashita, "Induction Acceleration System", in this conference
KEK, Ibaraki
SAMEER, Mumbai
Tokyo City University, Tokyo
The KEK-DA (Digital Accelerator) is a modification of the KEK 500 MeV booster*, in which an induction acceleration system is employed. It has an ability to accelerate arbitrary ions with their possible charge states**. An outline of the acceleration scenario is described and a necessary control system fully integrating the induction acceleration system is given in details. The KEK-DA is a rapid cycle synchrotron operating at 10 Hz; the accelerating pulse voltage must be dynamically varied in time to follow the ramping magnetic field. A novel technique combining the pulse density control and intermittent operation of acceleration cells is required. The intelligent gate control system which uses 1 GHz digital signal processors (DSPs) has been designed. Construction of the KEK-DA is in the final stage; installation of the induction cells and the power supplies are done. The whole system including gate control system is demonstrated with high voltage outputs,long-term stability of the system through a heat run is examined. Also a future plan which replaces DSPs by FPGA (Field Programmable Gate Array)is discussed.
* K.Takayama et al., JOURNAL OF APPLIED PHYSICS 101, 063304 (2007).
** K.Takayama et al., "KEK Digital Accelerator for Material and Biological Sciences" in this conference.
KEK, Ibaraki
Nagaoka University of Technology, Nagaoka, Niigata
Sokendai, Ibaraki
Tokyo City University, Tokyo
RBRC, Upton, Long Island, New York
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
Iwate university, Morioka, Iwate
A novel circular accelerator capable of accelerating any ions from an extremely low energy to relativistic energy is discussed. A digital accelerator (DA)* is based on the induction synchrotron concept, which had been demonstrated in 2006. All ions are captured and accelerated with pulse voltages generated by induction acceleration cell (IAC). The IAC is energized by the switching power supply, in which power solid-state conductors are employed as switching elements and their tuning on/off is maneuvered by gate signals digitally manipulated from the circulating signal of an ion beam. Acceleration synchronized with the revolution of the ion beam is always guaranteed. The concept is realized by renovating the KEK 500 MeV booster into the DA, introducing a laser ablation ion source. Ion energy of 85-140 MeV/au and intensity of 10+9 - 10+10 /sec are estimated and these ions will be delivered without any large-scale injector. Companion papers** will discuss more details of instruments of DA. Applications for innovative material sciences and life sciences will be briefly introduced as well as the outline of DA.
*K. Takayam, J. of Appl. Phys. 101 (2007) 063304.
**K.Takayama "Ion source and LEBT", T.Adachi "Injection and extraction system", T.Iwashita "Induction acceleration system" in this conference.
KEK/JAEA, Ibaraki-Ken
KEK, Ibaraki
JAEA/J-PARC, Tokai-mura
The Japan Proton Accelerator Complex includes the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main ring synchrotron (MR). Both synchrotrons use the high field gradient magnetic alloy (MA) loaded cavities. In RCS, 11 RF systems have been fully operational since December 2008. The RCS RF systems are operated with dual-harmonic acceleration voltages. Beam acceleration and bunch shape manipulation are efficiently taking place. 120kW of the neutron user operation was started at the Material and Life science facilities in November 2009. In MR synchrotron, the 5th RF system were installed in August 2009, and therefore 5 RF systems are now in operation. Beam commissioning for delivering protons to the hadron facility and neutrino beam experimental facility are under way. The neutrino user experiment is intended to start January 2010. Proton beam operation with more than 100kW is required. The approaches to realizing high intensity operation and the MR upgrade plan will be presented.
CEA, Gif-sur-Yvette
BNL, Upton, Long Island, New York
To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electro-magnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.
GSI, Darmstadt
FIAS, Frankfurt am Main
After partially completing the upgrade program of SIS18, the number of intermediate charge state heavy ions accelerated to the FAIR booster energy of 200 MeV/u, could be increased by a factor of 50. Meanwhile, more than 1010 Uranium ions with charge state 27+ have been accelerated with moderate beam loss by ionization and reasonably stable residual gas pressure conditions. The specific challenge for the SIS18 booster operation is the high cross section for ionization due to the low charge state in combination with gas desorption processes and the dynamic vacuum pressure. Especially for this operation mode which is requied to match the intensity requirements for FAIR, an extended upgrade program of SIS18 is presently ongoing and partially completed. The achieved progress in minimizing the ionization beam loss underlines that the chosen technical strategies described in this report are appropriate.
JINR, Dubna, Moscow Region
BINP SB RAS, Protvino, Moscow Region
JINR/LHE, Moscow
The 'Nuclotron-M' project started in 2007 is considered as the key point of the first stage of the NICA/MPD project. General goal of the 'Nuclotron-M' project is to prepare all the systems of the Nuclotron for its long and reliable operation as a part of the NICA collider injection chain. Additionally the project realization will increase the Nuclotron ability for realization of its current experimental program. Results of the last runs of the Nuclotron operation are presented.
WERC, Tsuruga , Fukui
We have operated the accelerator system which consists of a tandem accelerator and a synchrotron since the completion of the construction and beam commissioning at the Wakasa-wan Energy Research Center, Tsuruga, Japan in 2000. The acceleration voltage of the tandem accelerator amounts to 5 MV and is generated by the Dynamitron-type cascade voltage doubler rectifier. The beam from the tandem accelerator is transported to the MeV-ion experimental area for the irradiation to the industrial or biological material and for the ion beam analysis. The tandem beam is also injected to the 200 MeV proton synchrotron. The synchrotron beam has been used for the high energy irradiation and the cancer therapy. The tandem accelerator is used for a lot of purposes including cancer therapy, therefore, stable operation of the system and efficient sharing of the operation duration are required. Developments of the accelerator are presented putting a stress on the stable and efficient operation of the system in this paper.
GSI, Darmstadt
This paper describes the development of a new rf accelerating cavity based on novel magnetic alloy materials (MA-materials) for operation at harmonic number h=2 (f=0,43- to 2,8 MHz) to provide the necessary accelerating voltage for SIS18 injector operation with high intensity heavy ion beams in a fast operation mode with three cycles per second. The acceleration system consist of three units which are able to operate independently from each other. That is important, since each ion for FAIR has to cross the h=2-rf-system and in the case of a damage a reduced operation has to be ensured. Since the cavities are filled with lossy MA-ring-cores, which are iron based Finemet FT3M ring cores from Hitachi, the cavities show a broadband behaviour and thus no cavity tuning during the acceleration ramp will be necessary. Due to the high saturation field strength of Finemet (1,2 T) the overall length of all three cavity units can be very short. This is an important feature since due to many insertions which were additionally inserted into the synchrotron ring SIS12/18 in the meantime, the available length in SIS12/18 for the cavity units is with 4 m very short.
IAP, Frankfurt am Main
GSI, Darmstadt
For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six coupled CH-cavities operated at 325 MHz. Each cavity will be powered by a 3 MW klystron. For the second acceleration unit from 11.7 to 24.3 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH-cavities. For this second tank technical and mechanical investigations have been done in 2009 to prepare a complete technical concept for manufacturing. Recently, the construction of the prototype has started. The main components of this second cavity will be ready for measurements in spring 2010. At that time the cavity will be tested with dummy stems (made from aluminum) wich will allow precise frequency and field tuning. This paper reports on the technical development and achievements during the last year. It will outline the main fabrication steps towards that novel type of proton DTL.
ITEP, Moscow
The new heavy ion high current injector for ITEP-TWAC Facility is now under construction at ITEP for acceleration of ions with 1/3 charge to mass ratio up to energy of 7 MeV/u and beam current of 100 mA. The 81.5 MHz RFQ section based on 4 vane resonator with magnetic coupling windows is constructed for the beam energy of 1.566 MeV/u. The RF tuning of RFQ section has been presently completed and basically confirms the expected parameters calculated by 3D OPERA codes. The windows improve both azimuthal and longitudinal stabilization of the operating mode by increasing the separation from parasitic modes. The second section of 163 MHz H-type resonator is designed and in progress for construction. Status of machine construction activity and beam dynamics calculation are presented.
Fermilab, Batavia
University of Delhi, Delhi
650 MHz option for the high energy part of the 2.6 GeV, CW Project X linac is discussed. It may give significant benefits compared to current 1.3 GHz option based on the utilization of ILC-type beta=1 cavities. Results of the break point optimization for linac stages, cavity optimization and beam dynamics optimization are presented. Possible reduction in the number of cryomodules and linac length compared to the current linac project version is discussed. Cryogenic losses are analyzed also.
ELSA, Bonn
At the electron stretcher accelerator ELSA of Bonn University, an external beam of either unpolarized or polarized electrons is supplied to hadron physics experiments. In order to correct dynamic effects caused by eddy currents induced during the fast energy ramp, the transversal tunes have to be measured in situ with high precision. These measurements are based on the excitation of coherent betatron oscillations generated by a pulsed kicker magnet. Horizontal oscillations were excited using one of the injection kicker magnets. Since its installation in 2009 a newly designed kicker magnet enables measurements in the vertical plane as well. Betatron oscillation frequencies were derived from a fast Fourier transform of the demodulated BPM signals, showing a well pronounced peak at the tune frequency. Using this technique, tune shifts were measured and corrected successfully on the fast energy ramp. Measurement and correction of coherent synchrotron oscillations are feasible as well, utilizing a quite similar technique. Coherent synchrotron oscillations are excited by a phase jump of the acceleration voltage using an electrical phase shifter in the reference RF signal path.
KEK, Ibaraki
Osaka University, Osaka
Proton beam extinction, defined as a residual to primary ratio of beam intensity, is one of the most important parameters to realize the future muon electron conversion experiment (COMET) proposed at J-PARC. To achieve the required extinction level of 10-9, we started measuring beam extinction at main ring (MR) as the first step. The newly developed beam monitor was installed into the abort beam line and the first measurement was successfully performed by using the fast-extracted MR beam. We found that empty RF buckets of RCS, in which all protons were considered to be swept away by a RF chopper before injection to RCS,, contained about 10-5 of the main beam pulse due to chopper inefficiency. We are now developing a new beam monitor with improved performance for further studies at the abort line. In addition, we have started new measurements at the different stage of proton acceleration, i.e. at Linac, 3-50 BT line, and the main ring. In this paper, we present recent results and future prospect of beam extinction measurements.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
We present preliminary results of beam diagnostics for the world's first Non-Scaling FFAG Accelerator 'EMMA'. Amongst other means, a single-shot/turn-by-turn BPM system is used, that was first tested on the ALICE injector. The BPM system utilizes a front-end conversion of button pickup signals into flat-top-envelope 700 MHz bursts, time-domain multiplexing (in each plane, signals are made spaced by 13.8 ns), and the manufacture of both synchronous detector and ADC clocks directly from the beam signal. The system performance is discussed; results of beam-based resolution measurement are given. First turn beam trajectories furthest from the Septum and Kicker are presented.
NSC/KIPT, Kharkov
The electron injector for a storage ring is one of numerous applications of the rf linacs of intensive short-pulsed beams with duration about 100 ns, current about 1 A and energy of particles in a few ten MeB. Since acceleration of intensive short-pulsed beams takes place in transient mode, then the energy spread is determined by both intro- and multi- bunch spread. Getting the energy spread less than 1% is the actual problem. In this work we simulate numerically unsteady self-consistent dynamics of charged particles in an rf linac that consist of a low-voltage (25 keV) thermionic gun, a compact evanescent wave buncher, a traveling wave accelerating structure. For transient beam loading compensation a method of delay of a beam relatively rf pulse are applied. The simulation takes into account influence on the beam dynamic of such factors as: initial energy and phase spread; sliding of particles in relation to a wave in the initial part of accelerating section; temporal dependence of phase and energy of bunches at the enter of section; space charge field.
NSC/KIPT, Kharkov
At present work the results of numeral simulation of electron dynamics in an unhomogeneous disk-loaded waveguide which is used in the S-band linac are presented. Two approaches taking into account the self-fields of beam radiation are considered: the first method estimative based on the power diffusion equation; the second one based on of self-consistent equations of field excitation and particles motion. The self-consistent approach showed the presence of substantial phase slipping of particles in the homogeneous part of the rf structure, conditioned by the reactive beam loading.
NIRS, Chiba-shi
AEC, Chiba
Toshiba Medical Systems Corporation, Tochigi
In the routine operation of HIMAC synchrotron, a pulse system of field change with 0.2 Gauss in the monitor dipole magnet (B-clock) is used to generate pattern data in the acceleration system. To eliminate error pulse due to noise in analogue field signal, a clock system locked to a 1.2kHz clock for a power supplies was developed, which can be used to generate pattern data of an acceleration system with maximum frequency of 192kHz. This 1.2kHz clock is synchronized to a power line frequency of 50Hz that will fluctuate about 0.1%, so the clock of 192kHz must also follow this frequency fluctuation. To demonstrate the performance of new clock system, we have tested beam acceleration, and compared with the conventional B-clock system. Acceleration efficiencies were checked with changing these clock rates in the both systems. With these tests, we have found that the relatively low clock rate in the newly developed system is enough to get good acceleration performance. In this paper the clock system, and their beam tests will be presented.
IPM, Tehran
CERN, Geneva
The pulse compressor is located after the klystron to increase the power peak by storing the energy at the beginning and releasing it near the end of klystron output pulse. In the CTF3 [1] pulse compressors a doubling of the peak power is achieved according to our needs and the machine parameters. The magnitude of peak power, pulse length and flatness can be controlled by using a phase modulator for the input signal of klystrons. A C++ code is written to simulate the pulse compressor behaviour according to the klystron output pulse power. By manually changing the related parameters in the code for the best match, the quality factor and the filling time of pulse compressor cavities can be determined. This code also calculates and sends the suitable phase to the phase modulator according to the klystron output pulse power and the desired pulse length and peak power.
JAEA/J-PARC, Tokai-mura
KEK/JAEA, Ibaraki-Ken
J-PARC, KEK & JAEA, Ibaraki-ken
KEK, Ibaraki
Applying narrow band longitudinal noise to the beam in J-PARC Main Ring in flattop, while the acceleration voltage is off might help to counteract the effect of ripple on the slow extraction. For this purpose, a complex noise sequence output by DSP modulates a custom made DDS synthesizer to create single side spectra without carrier. The noise is calculated starting from a description in frequency domain. Then an algorithm creates narrow band spectra with optimized behavior in time domain. Frequency domain data is transformed to time domain, and the amplitude is smoothed. The smoothed data is transformed back to frequency domain, and the spectral shape is restored. This process repeats until the amplitude in time domain has converged, while the desired spectrum shape is preserved. Noise generated in this way can be tailored for different requirements. We show the signal properties, the hardware, and preliminary beam test results, when the noise is applied to the MR RF system.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
I-Tech, Solkan
The Low Level RF (LLRF) control system on EMMA (Electron Model for Many Applications), the world's first Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator is presently being installed and commissioned at Daresbury Laboratory. The LLRF is required to synchronize with ALICE (Accelerators and Lasers in Combined Experiments) its injector, which operates at 1.3GHz, and to produce an offset frequency as required (+1.5Mhz to -4MHz) to then maintain the phase and amplitude of the 19 copper RF cavities of the EMMA machine. The design and commissioning of the LLRF system is presented.
BNL, Upton, Long Island, New York
The proposed electron ion collider, eRHIC, requires large average polarized electron current of 50mA, which is more than 20 times higher than the present experiment results of single polarization source, such as GaAs. To achieve the current requirement of eRHIC, we have designed the multi-cathode DC electron gun for injection. 24 GaAs cathodes will be prepared and emit electrons at the arranged pattern. Despite of ultra-high vacuum and precise timing, multi-cathode DC electron gun has high demand on the electric field symmetry, magnetic field shielding, and arcing prevention. In the paper, we present the 3D simulation results of the latest model for the multi-cathode DC electron gun. The results will give guidance to the actual design in the future.
LAL, Orsay
INFN/LNF, Frascati (Roma)
IN2P3 IPNL, Villeurbanne
Providing a high quality and sufficient high current positron beam for the ultra high luminosity B-factory SuperB is a major goal. In this paper a proposition for positrons production and capture scheme based on low energy electrons up to1 GeV is presented. For this technique, several types of flux concentrator used to capture the positrons are being studied. The following accelerating section bringing the positrons up to 280 MeV and the total yield for L-band and S-band type accelerators are given. Also the result of the benchmark between ASTRA and a LAL code based on Geant4 toolkit simulation is discussed.
Brunel University, Middlesex
STFC/RAL, Chilton, Didcot, Oxon
The University of Liverpool, Liverpool
The Non Scaling Fixed Field Alternating Gradient EMMA has a compact linear lattice. Effect of Fringe Field on the beam has to be studied carefully. A numerical magnetic field map is generated by magnet measurements or magnet design softwares. We developed a technique that produces from the numerical field map, a dynamical map for a particle travelling in the entire EMMA cell for a reference energy without acceleration. Since the beam dynamics change with energy, a set of maps have been produce with different reference energies between 10 and 20MeV. For each reference energy, simulated tune and time of flight (TOF) have been compared with results in Zgoubi - tracking directly through numerical field map. The range of validity of a single map has been investigated by tracking particle with large energy deviation. From that, a sensible acceleration scheme has been implemented.
yoel.giboudot@stfc.ac.uk
NTHU, Hsinchu
NSRRC, Hsinchu
A THz-pulse-train photoinjector is under construction at the High-energy OPtics and Electronics (HOPE) Lab. at National Tsinghua University, Taiwan. This photoinjector is believed to be useful for generating high-power THz radiation, as well as for driving or loading a plasma-wave accelerator. A THz laser beat wave with full tunability in its beat frequency is employed to induce the emission of the THz electron pulses from the photoinjector. We show in our study that such a photoinjector is capable of generating periodically bunched MeV electrons with a bunching factor larger than 0.1 at THz frequencies for a total amount of 1nC charges in a 10-ps time duration. We will also present a driver laser technology that can tune the electron bunch frequency with ease and help the growth of the high harmonics in the bunching spectrum of accelerated electrons. Experimental progress on this photoinjector will be reported in the conference. The authors gratefully acknowledge funding supports from National Scienc Council under Contract NSC 97-2112-M-007-018 -MY2, National Synchrotron Radiation Research Center under Project 955LRF01N, and National Tsinghua University under Project 98N2534·101.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
Transverse bunch by bunch feedback systems for J-PARC MR accelerator has been designed and tested. Bunch positions are detected by Log-ratio position detection systems with center frequency of 12 MHz. The digital filter which consists of two LLRF4 boards samples the position signal with 64 times of RF frequency. Up to four sets of 16 tap FIR filter with one-turn delay and digital shift gain can be used. Preliminary results of beam test of the system are also shown.
Fermilab, Batavia
In the low-energy part of the Project X H-linac there families of 325 MHz SC single spoke cavities will be used, having beta = 0.11, 0.22 and 0.4. Two versions of the beta = 0.11 cavity were considered: low-beta single-spoke cavity and half-wave cavity. Results of detailed optimization of both versions are presented. Single spoke cavity was selected for the linac because of higher r/Q. Results of the beam dynamics optimization for initial stage of the linac with beta=0.11 single spoke cavity are presented as well.
JAEA, Ibaraki-ken
In J-PARC RCS, horizontal closed orbit distortion (COD) which is ±2 or 3mm in amplitude was observed all over the ring. Main component of the horizontal COD is 1kHz, phase variation period about 140 seconds. This paper demonstrates phase variation of the 1kHz horizontal COD caused by switching ripple from dipole magnet power supply. To suppress the phase variation of the horizontal COD, switching timing of the dipole magnet power supply was synchronized J-PARC timing system.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
J-PARC, KEK & JAEA, Ibaraki-ken
KEK, Ibaraki
At the J-PARC 3-GeV injection, the injection painting area is designed to be different for supplying the MLF (Material Life Science Facility) and MR (50GeV Main Ring) beams. Along with the injection system in the ring, pulsed switching magnets which are installed in the injection beam-line should also have a function to control the beam orbit at 25Hz. The deflection angle ranges from 3 to 38 mrad to meet the user operation as well as the beam physics run.
ANL, Argonne
Euclid TechLabs, LLC, Solon, Ohio
In this paper, we present a linear collider concept based on drive beam generation from an RF photoinjector, and employing dielectric structures for power extraction and acceleration. The collider is based on a modular design with each module providing 100 GeV net acceleration. A high current drive beam is produced using a low frequency RF gun (~ 1GHz), and subsequently accelerated to ~1 GeV using conventional standing wave cavities. High frequency (20 GHz) RF power, extracted from the drive beam using a low impedance dielectric structure, is used to power the main linacs, which are based on high impedance high gradient dielectric loaded accelerating structures. We envision this scheme will produce high gradients (300 MeV/m), leading to a very compact design. The modularity of the design will allow a staged construction that will enable extension to multi-TeV energies.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
CERN, Geneva
Fermilab, Batavia
BNL, Upton, Long Island, New York
Muons, Inc, Batavia
LBNL, Berkeley, California
We discuss alternative designs of the muon capture front end of the Neutrino Factory International Design Study (IDS). In the front end, a proton bunch on a target creates secondary pions that drift into a capture channel, decaying into muons. A sequence of RF cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. This design is affected by limitations on accelerating gradients within magnetic fields. The effects of gradient limitations are explored, and mitigation strategies are presented.
Imperial College of Science and Technology, Department of Physics, London
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The international Muon Ionisation Cooling Experiment (MICE) is designed to provide a proof of principal of the ionisation cooling technique proposed to reduce the muon beam phase space at a future Neutrino Factory or Muon Collider. The pion production target is a titanium cylinder that is dipped into the proton beam of the Rutherford Appleton Laboratory's ISIS 800 MeV synchrotron. Studies of the particle rate in the MICE muon beam are presented as a function of the beam loss induced in ISIS by the MICE target. The implications of the observed beam loss and particle rate on ISIS operation and MICE data taking is discussed.
Sheffield University, Sheffield
The MICE experiment requires a beam of low energy muons to demonstrate muon cooling. A target mechanism has been developed that inserts a small titanium target into the circulating ISIS beam during the last 2ms before extraction. The target mechanism has been in operation in the ISIS beam during 2009 and a large set of useful data has been obtained describing the target's operational parameters. This has allowed the commissioning of the initial section of the MICE beam line and instrumentation, and the close monitoring of target performance. This work describes these target parameters and presents some of the results from operational shifts.
Sheffield University, Sheffield
STFC/RAL, Chilton, Didcot, Oxon
The MICE experiment uses a beam of low energy muons to test the feasibility of ionisation cooling. This beam is derived parasitically from the ISIS accelerator at the Rutherford Appleton Laboratory. A target mechanism has been developed and deployed that rapidly inserts a small titanium target into the circulating proton beam immediately prior to extraction without undue disturbance of the primary ISIS beam. The first target drive was installed in ISIS during 2008 and operated successfully for over 100,000 pulses. A second upgraded design was installed in 2009 and is currently in operation. The technical specification for this upgraded design is given and the motivation for many of the improvements is discussed. In addition possible future improvements to the current design are discussed.
LANL, Los Alamos, New Mexico
We propose a high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field. The acceleration starts immediately after collection of pions from a target by solenoidal magnets and brings muons to a kinetic energy of about 200 MeV over a distance of the order of 10 m. At this energy, both an ionization cooling of the muon beam and its further acceleration in a superconducting linac become feasible. The project presents unique challenges ' a very large energy spread in a highly divergent beam, as well as pion and muon decays ' requiring large longitudinal and transverse acceptances. One potential solution incorporates a normal-conducting linac consisting of independently fed 0-mode RF cavities with wide apertures closed by thin metal windows or grids. The guiding magnetic field is provided by external superconducting solenoids. The cavity choice, overall linac design considerations, and simulation results of muon acceleration are presented. While the primary applications of such a linac are for homeland defense and industry, it can provide muon fluxes high enough to be of interest for physics experiments.
LANL, Los Alamos, New Mexico
Many groups are working on muon accelerators for future neutrino factory and muon colliders. One of the applications of muon accelerator is muon radiography which is a promising method to investigate large objects taking advantage of the long penetration lengths of muons. We propose a compact muon accelerator that has a large energy and a phase acceptance to capture relatively low energy pion/muon of 10 - 100 MeV and accelerates them to 200 MeV without any beam cooling. Like an RFQ, mixed buncher/acceleration mode provides phase bunching during the acceleration. Our current design uses 805 MHz zero-mode normal-conducting cavities with 35 MV/m peak field*. The normal conducting cavities are surrounded by superconducting coils that produce 5 T focusing field. We ran Monte Carlo simulations to optimize linac parameters such as frequency and acceleration gradient. Muon energy loss and scattering effects at the cavity windows are studied, too. The simulation showed that about 10 % of the pion/muon injected into the linac can be accelerated to 200 MeV. Further acceleration is possible with superconducting linac.
* S. Kurennoy et al., IPAC 2010.
STFC/RAL, Chilton, Didcot, Oxon
EMMA is the world's first non-scaling fixed field alternating gradient accelerator and is being constructed at the STFC Daresbury Laboratory. Experience from the initial commissioning phases (from early 2010) will be reported and lessons for future machines of a similar type will be discussed. The present experimental status and future plans will also be reported.
JLAB, Newport News, Virginia
Muons, Inc, Batavia
Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We discuss the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed Linac quadrupoles and arc magnets to allow the maximum number of passes. The design will include the optics for the multi-pass linac and droplet-shaped return arcs.
UCLA, Los Angeles, California
SLAC, Menlo Park, California
USC, Los Angeles, California
Given the recent success of >GV/m dielectric wakefield accelerator (DWA) breakdown experiments at SLAC, and follow-on coherent Cerenkov radiation production at the UCLA Neptune, a UCLA-USC-SLAC collaboration is now implementing a new set of experiments that explore various DWA scenarios. These experiments are motivated by the opportunities presented by the approval of FACET facility at SLAC, as well as unique pulse-train wakefield drivers at BNL. The SLAC experiments permit further exploration of the multi-GeV/m envelope in DWAs, and will entail investigations of novel materials (e.g. CVD diamond) and geometries (Bragg cylindrical structures, slab-symmetric DWAs), and have an over-riding goal of demonstrating >GeV acceleration in ~33 cm DWA tubes. In the nearer term before FACET's commissioning, we are planning measurements at the BNL ATF, in which we drive ~50-200 MV/m fields with single pulses or pulse trains. These experiments are of high relevance to enhancing linear collider DWA designs, as they will demonstrate potential for high efficiency operatio with pulse trains.
BNL, Upton, Long Island, New York
High energy polarized proton beams are desired for exploring the proton spin structure as well as other spin dependent measurements. However, depolarizing mechanisms due to the interaction between the spin motion and the magnetic fields challenges accelerating polarized protons to high energy in circular accelerators. Several decades of efforts in developing techniques to preserve polarization to high energy have finally led to the success of the polarized proton program at the Brookhaven Relativistic Heavy Ion Collider (RHIC). Designed to provide polarized proton collisions up to 250GeV, RHIC is equipped with two Siberian snakes to avoid both intrinsic and imperfection depolarizing resonances. Currently, polarization has been preserved up to 100 GeV at RHIC with precise control of orbit and betatron tunes. The polarized protons were first brought into collisions at 250GeV in RHIC in 2009, and depolarizations were observed between 100 GeV to 250 GeV. This presentation reports the progress of RHIC polarized proton program. Strategies of how to preserve the polarization through the RHIC injectors are also presented.
KEK, Ibaraki
JAEA/J-PARC, Tokai-mura
The RF cavity using Magnetic Alloy (MA) cores has been developed for achieving the high field gradient in J-PARC. For reducing the beam loading effects, the Q-value of the RF cavities in the Main Ring (MR) is controlled by using the cut-core configuration. In order to check the effect of HOMs between the cut-core gap, a simulation method of MA cores was studied and electromagnetic fields of excitation modes have been calculated by HFSS. We present the detail of the simulation method of MA cores and the HOM analysis of the cavity with the cut-cores.
KEK, Ibaraki
SLAC, Menlo Park, California
CERN, Geneva
A CERN-SLAC-KEK collaboration on high gradient X-band accelerator structure development for CLIC has been ongoing for three years. The major outcome has been the demonstration of stable 100 MV/m gradient operation of a number of CLIC prototype structures. These structures were fabricated basically using the technology developed from 1994 to 2004 for the GLC/NLC linear collider initiative. One goal has been to refine the essential parameters and fabrication procedures needed to realize such high gradient routinely. Another goal has been to develop structures with stronger dipole mode damping than those for GLC/NLC. The latter requires that surface temperature rise during the pulses be higher, which may increase the breakdown rate. Structures with heavy damping will be tested in late 2009/early 2010, and this paper will present these results together with some of the earlier results from non-damped structures and structures built with a quadrant geometry.
KEK, Ibaraki
KEK/JAEA, Ibaraki-Ken
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
Magnetic alloy cavities are successfully used for J-PARC synchrotrons. These cavities generate much higher RF voltage than ordinary ferrite cavities. For future upgrades of J-PARC facilities, a higher field gradient is necessary. It was found that the characteristics of magnetic alloy is improved by a new annealing scheme under magnetic field. A large production system using an old cyclotron magnet is under construction for the J-PARC upgrade. The status of core development will be reported.
KEK, Ibaraki
BNL, Upton, Long Island, New York
An RF system using Magnetic Alloy is considered as an option to study the beam dynamics of a linear non-scaling FFAG. Such an FFAG may have many resonances, which affect the beam more when the beam crosses them slowly. The RF system aims at ordinary RF bucket acceleration with an RF frequency sweep of 3 % in 100 turns. The cavity has only 10 cm length to fit in a short straight section. The required RF voltage is 100 kV per turn and each of the three cavities is designed to generate 50 kV.
Toshiba, Yokohama
JASRI/SPring-8, Hyogo-ken
TOSHIBA is manufacturing the L-band acceleration system for the SPring-8 Joint Project for XFEL. We have developed a new type duct-shaped SiC dummy load for its power distribution system. The load terminates a WR650 waveguide and can absorb the maximum mean power of 10kW. In order to reduce VSWR less than 1.1 in the frequency range of 1.428GHz, we shaped the SiC absorber into a 35cm long tapered cylinder and mounted matching stubs in the waveguide near the inlet of the load. The SiC absorber was fit into a cylindrical copper with efficient water-cooling channels. The design and manufacture and the low-power tests of our original dummy load are described in this paper.
HUST, Wuhan
The design study of a 10MeV compact cyclotron CYCHU-10 has been developed at Huazhong University of Science and Technology (HUST). We developed the basic shapes and dimensions and carried out the simulations for the CYCHU-10 cavities with 3D numerical calculation softwares in this paper. The distributions of electromagnetic field are illustrated by means of the electromagnetic and structural analysis, and the wooden model test is preformed as well. In addition, this paper gives mechanical tolerance effects which deformed due to the limit of mechanical working of cavities under practical conditions. This work helps to evaluate the performances of capacitive frequency trimmer design.
MEPhI, Moscow
Nowadays the DC potential using was proposed for ion beam focusing in linear accelerators. It was proposed to use the DC potential for combined beam focusing (electrostatic focusing and focusing by using of higher RF field spatial harmonics) in bunching section of linac *. These accelerators use an IH-type resonator. So-called linear undulator accelerator (UNDULAC) was proposed for ribbon ion beam bunching and acceleration **. One of possible scheme of UNDULAC can be realized using an electrostatic undulator in E-type resonator. In this report the different types of the electrostatic potential inputting into resonator will discussed.
* P.А. Demchenko at al., Problems of Atomic Science and Technology, 2008, 5 (50), pp. 28-32.
** E.S. Masunov at al., Radiation Physics and Chemistry, 2001, v. 61, рр. 491-493.
RadiaBeam, Berkeley, California
The distribution of electromagnetic fields in an RF cavity is primarily determined by the geometry of the RF cavity. The quality factor (Q-factor) of an RF cavity characterizes RF losses in the cavity: an RF cavity having a higher Q-factor is a more efficient user of RF power. However, a cavity having a lower Q-factor can operate on a wider range of frequencies, shorter filling time and may be more stable and less sensitive to input power perturbations. A method is discussed in this paper for an RF cavity that provided a desired Q-factor for the cavity while enabling a desired field distribution for electron acceleration within the cavity. The structure forming the inner wall of the RF cavity may be comprised of different types of material(such as copper and steel). Using different materials for different portions of the inner walls forming a cavity will cause different Q-factors for the cavity while the shape of the cavity remains constant.
contact: ding@radiabeam.com
KEK, Ibaraki
In J-PARC 50GeV synchrotron ring, large vacuum pressure rises above 10-3 Pa are found at 30GeV acceleration final stage of intensity over 1013 protons per pulse in the chambers of the in-vacuum electrostatic septum magnet for the slow-extraction(SX), magnetic septum for SX, and the kicker magnet for the fast-extraction. This pressure rise depends on beam intensity and peak-current, and can be reduced by continuous beam operations, such as scrubbing with proton beam, secondary emission electrons and other cations of remaining gasses or desorptions.
RIKEN Nishina Center, Wako
The RI beam factory at RIKEN Nishina Center needs high intensity of uranium ion beams. We have used so far the RFQ pre-injector upstream of the linac system, in which the extraction voltage of the ECR ion source is as low as 5.7 kV for the uranium beam. However, for much higher intensity beams from a newly developed superconducting ECR ion source, such a low voltage was expected to significantly increase their emittance due to the space charge effect. To reduce this effect, we prepared a new pre-injector line of 127 kV for uranium beams by placing the ion source on a high-voltage terminal. In this paper we present the design of the 127 kV medium energy beam transport, MEBT, and show the measured results through the line.
Imperial College of Science and Technology, Department of Physics, London
JLAB, Newport News, Virginia
International Design Study for the Neutrino Factory (IDS-NF) assumes the first stage of muon acceleration (up to 900 MeV) to be implemented with a solenoid based Linac. The Linac consists of three styles of cryo-modules,containing focusing solenoids and varying number of SRF cavities for acceleration. Fringe fields of the solenoids and the focusing effects in the SRF cavities have significant impact on the transverse beam dynamics. Using an analytical formula,the effects of fringe fields and cavities are studied in MAD-X. The resulting betatron functions are compared with the results of beam dynamics simulations using OptiM code.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
The RF system on EMMA (Electron Model for Many Applications), the world's first Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator is presently being installed and commissioned at Daresbury Laboratory. The RF system is required to provide precise amplitude and phase control to each of the 19 identical normal conducting, 1.3 GHz RF cavities which provide the acceleration of the electron beam from 10 MeV to 20 MeV. The system incorporates a high power RF system, which includes a single 100 kW Inductive Output Tube (IOT), a unique RF distribution system and a low level RF (LLRF) control system. The design of the RF system and the commissioning progress to date is presented.
KERI, Changwon
Using the nonlinear interaction between the high power laser and the plasma, we can generate strong acceleration field, called the laser wake field acceleration. The plasma density is very crucial to generate high energy electron. In this work, we studied the effect of the plasma density structure on the accelerated electron energy. We used 20 TW, 40 fs laser system to generate the plasma wakefield. A gas jet was used as a target. The plasma density was controlled by the back pressure of the gas nozzle and measured by the interferometer. The accelerated electron energy was measured using the electron energy spectrometer with 0.5 T magnet. The bunch charge was measured integrated charge transformer (ICT). When the plasma density is uniform, 2×1019 cm-3 we can generate 200 MeV electron beam with bunch charge 33 pC. The electron beam divergence was less than 5 degree. If there exists the downward density tramp, the electron energy is only 50 MeV. The PIC simulation also indicates that if there is density ramp structure, the electron is not accelerated well. In this presentation, the overall experimental and simulation results are presented.
APRI-GIST, Gwangju
In recent years, the laser-driven plasma wakefield acceleration has attracted much attention as it has a much higher acceleration gradient (>100 GeV/m) compared with the RF-based conventional accelerators. In the past, the supersonic gas jet method for plasma wakefield acceleration was widely used, but this method has a limitation in acceleration distance and energy because the focused laser beam is diffracted severely over a very short distance (~ a few mm range). To avoid the diffraction problem, a capillary plasma source can be used, where a high power laser beam can be guided over a long distance (~ a few cm range) by a parabolic plasma density profile in the capillary plasma channel. We have developed a gas-filled capillary plasma source for generation of GeV-level electron beams in collaboration with the University of Oxford team. In this presentation, the detailed test results and the near-future experimental plan for GeV-level e-beam generation are shown.
Tech-X, Boulder, Colorado
Stanford University, Stanford, California
SLAC, Menlo Park, California
Photonic crystal waveguides are promising candidates for laser-driven accelerator structures because of their ability to confine a speed-of-light mode in an all-dielectric structure. Because of the difference between the group velocity of the waveguide mode and the particle bunch velocity, fields must be coupled into the accelerating waveguide at frequent intervals. Therefore efficient, compact couplers are critical to overall accelerator efficiency. We present designs and simulations of high-efficiency coupling to the accelerating mode in a three-dimensional photonic crystal waveguide from a waveguide adjoining it at 90 degrees. We discuss details of the computation, including an optimization routine to modify the geometric parameters of the coupler for maximum efficiency, the resulting transmission, and estimates of the fabrication tolerance for these devices. We include some background on the accelerator structure and photonic crystal-based optical acceleration in general.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
Cockcroft Institute, Warrington, Cheshire
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
The first results from commissioning EMMA - the Electron Model of Many Applications- are summarised in this paper. EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). EMMA will be the world's first non-scaling FFAG and the paper will outline the characteristics of the beam injected in to the accelerator as well as summarising the results of the extensive EMMA systems commissioning. The paper will report on the results of simulations of this commissioning and on the progress made with beam commissioning.
IF-UFRGS, Porto Alegre
In this work the nonlinear relativistic propagation of intense lasers in plasmas is investigated. It is known that, under appropriate conditions, the ponderomotive force associated with the laser envelope can excite large amplitude electron waves (wakefields), which can be of interest for particle acceleration schemes. Numerical solutions showing some of the possible behaviors of this system are presented and compared to analytical ones, obtained through an effective potential approach using a one-dimensional Lagrangian formalism.
HHUD, Dusseldorf
National University of Defense Technology, Changsha, Hunan
By using multi-dimensional particle-in-cell simulations, we investigate the stability of proton beam acceleration in a two-specie ultra-thin foil. In this two-specie regime, the lighter protons are initially separated from the heavier carbon ions due to their higher charge-to-mass ratio Z/m. The laser pulse is well-defined so that it doesn't penetrate the carbon ion layer. The Rayleigh-Taylor-like (RT) instability seeded at the very early stage then only degrades the acceleration of the carbon ions which act as a "cushion" for the lighter protons. Due to the absence of proton-RT instability, the produced high quality mono-energetic proton beams can be well collimated even after the laser-foil interaction concludes.
Indian Institute of Technology Delhi, Plasma Physics Group, New Delhi
Indian Institute of Technology Delhi, New Delhi
A Gaussian whistler pulse is shown to cause ponderomotive acceleration of electrons in a plasma when the peak whistler amplitude exceeds a threshold value. The threshold amplitude decreases with the ratio of plasma frequency to electron cyclotron frequency ωp / ωc. However above the threshold amplitude the acceleration energy decreases with ωp / ωc. The electrons gain velocities about twice the group velocity of the whistler. For acceleration of electrons one requires a whistler pulse of ω > ωc/2. It is seen that to enhance the energy gain the value of peak laser amplitude should be above a threshold value.
Rome University La Sapienza, Roma
INFN/LNF, Frascati (Roma)
ENEA C.R. Frascati, Frascati (Roma)
Protons generated by the irradiation of a thin metal foil by a high-intensity short-pulse laser have shown to posses interesting characteristics in terms of energy, emittance, current and pulse duration. They might therefore become in the next future a competitive source to conventional proton sources. Previous theoretical and numerical studies already demonstrated the possibility of an efficient coupling between laser-plasma acceleration of protons with traditional RF based beam-line accelerator techniques. This hybrid proton accelerator would therefore benefit from the good properties of the laser-based source and from the flexibility and know-how of beam handling as given from RF based accelerator structure. The proton beam parameters of the source have been obtained from published laser interaction experimental results and are given as input to the numerical study by conventional accelerator design tools. In this paper we discuss recent results in the optimization and design of the such hybrid schemes in the context of proton accelerators for medical treatments.
Lancaster University, Lancaster
Cockcroft Institute, Lancaster University, Lancaster
In this paper we examine the effect of introducing an Electromagnetic metamaterial into a Travelling Wave structure to mediate inverse Cherenkov acceleration. Electromagnetic metamaterials are artificial materials that consist of macroscopic structures that yield an effective permittivity and permeability less than zero. The properties of metamaterials are highly frequency dependent and give rise to very novel dispersion relationships. We show that the introduction of a specifically designed metamaterial into the interaction region gives rise to a novel dispersion curve yielding a unique wave-particle interaction. We demonstrate that this novel wave-particle interaction gives rise energy exchange from wave to beam over an extended interaction regime. We also discuss the benefits and issues that arise from having a metamaterial in a high vacuum high power environment with a specific focus on the issue of loss in metamaterial structures.
UCLA, Los Angeles
Manhattanville College, Purchase, New York
The Micro-Accelerator Platform is an optical-wavelength microstructure for laser acceleration of particles, currently under development at UCLA. It is a slab-symmetric structure and can be constructed in layers using existing nanofabrication techniques. We present several possible fabrication techniques and preliminary experimental outcomes for manufacturing this structure.
UCLA, Los Angeles
PBPL, Los Angeles
Manhattanville College, Purchase, New York
This paper extends the physics of the Micro-Accelerator Platform (MAP), which is in development as an optical structure for laser acceleration of relativistic electrons. The MAP is a resonant, optical-scale, slab-symmetric device that is fabricated from dielectric materials using layer-deposition techniques. For stand-alone applications, low-energy electrons (beta ~ 0.3) must be synchronously accelerated to relativistic speeds for injection into the MAP. Even lower energies are desired for other particle species (e.g. protons or muons). In this paper, we present design and simulation studies on a tapered geometry and associated coupling scheme that can produce synchronous acceleration at beta < 1 within a MAP-like structure.
MPI-P, München
CERN, Geneva
BINP SB RAS, Novosibirsk
HHUD, Dusseldorf
Proton driven plasma wakefield acceleration holds promise to accelerate a bunch of electrons to the energy frontier in a single acceleration channel. To verify this novel idea, a demonstration experiment is now being planned. The idea is to use the high energy proton bunches from the Super Proton Synchrotron (SPS) at CERN, to shoot them into a plasma cell and drive large amplitude of plasma wake. The interactions between the plasma and protons are simulated and the results are presented in this paper.
MPI-P, München
A high energy, intense and short proton bunch can be employed to excite an interesting plasma wakefield for the electron beam acceleration. To excite a large amplitude of plasma wave, a short driver is thus required. In this paper, several proton bunch compression scenarios are analyzed. A magnetic bunch compressor is designed to compress the SPS proton beam for the demonstration experiment at CERN. The simulation results of bunch compression are given.
LETI, Saint-Petersburg
Euclid TechLabs, LLC, Solon, Ohio
The strong focusing of high current relativistic electron beams in multi-bunch wakefield acceleration is investigated. These beams are used for generating wake fields in dielectric loaded accelerating structures. We consider ramped charge distribution in the sequence of high current drive bunch. It is shown that the beam focusing system dumping beam break-up effect and elongating of a maximum distance the high current beam can travel determines the effectiveness of the energy transfer to the accelerated electron bunch. The optimal parameters of the focusing system on the basis of self-consistent transverse dynamics analysis are determined.
ANL, Argonne
Euclid TechLabs, LLC, Solon, Ohio
The AWA Facility is dedicated to the study of advanced accelerator concepts based on electron beam driven wakefields. The facility employs an L-band photocathode RF gun to generate high charge short electron bunches, which are used to drive wakefields in dielectric loaded structures, as well as in metallic structures. Accelerating gradients as high as 100 MV/m have been reached in dielectric structures, and RF pulses of up to 44 MW have been generated at 7.8 GHz. In order to reach higher accelerating gradients and higher RF power levels, several upgrades are underway: (a) a new RF gun with higher QE photocathode will replace the present drive gun; (b) the existing RF gun will generate a witness beam to probe the wakefields; (c) three new 25 MW L-band RF power stations will be added to the facility; (d) five additional linac structures will bring the beam energy up from 15 MeV to 75 MeV. The drive beam will consist of bunch trains of up to 32 bunches, with up to 60 nC per bunch. The goal of future experiments is to reach accelerating gradients of several hundred MV/m and to extract RF pulses with GW power level.
Euclid TechLabs, LLC, Solon, Ohio
LETI, Saint-Petersburg
Fermilab, Batavia
Materials possessing variations in the permittivity as a function of the electric field exhibit a variety of phenomena for electromagnetic wave propagation such as frequency multiplication, wave steepening and shock formation, solitary waves, and mode mixing. New low loss nonlinear microwave ferroelectric materials present interesting and potentially useful applications for both advanced and conventional particle accelerators. Accelerating structures (either wakefield-based or driven by an external rf source) loaded with a nonlinear dielectric may exhibit significant field enhancements. In this paper we will explore the large signal permittivity of these new materials and applications of nonlinear dielectric devices to high gradient acceleration, rf sources, and beam manipulation. We describe planned measurements using a planar nonlinear transmission line to characterize in detail the electric field dependence of the permittivity of these materials. We will present a concept for a nonlinear transmission line that can be used to generate short, high intensity rf pulses to drive fast rf kickers.
BNL, Upton, Long Island, New York
Imperial College of Science and Technology, Department of Physics, London
UMD, College Park, Maryland
Stony Brook University, StonyBrook
Recent theoretical and experimental studies point to better efficiency of laser-driven ion acceleration when approaching the critical plasma density regime. Simultaneously, this is the condition for observing solitons: "bubble"-like quasi-stationary plasma formations with laser radiation trapped inside. Exploring this regime with ultra-intense solid state lasers is problematic due to the lack of plasma sources and imaging methods at ~1021/cc electron density. The terawatt picosecond CO2 laser operated at Brookhaven's Accelerator Test Facility offers a solution to this problem. At 10 μm laser wavelength, the CO2 laser shifts the critical plasma density to 1019/cc which is attainable with gas jets and can be optically probed with visible light. Capitalizing on this approach, we focused a circular-polarized CO2 laser beam with a0=0.5 onto a hydrogen gas jet and observed monoenergetic proton beams in the 1 MeV range. Simultaneously, the laser/plasma interaction region has been optically probed with a 2nd harmonic picosecond Nd:YAG laser to reveal stationary soliton-like plasma formations. 2D PIC simulations agree with experimental results and aid in their interpretation.
CAEP/IFP, Mainyang, Sichuan
Linear Induction Accelerator (LIA) is a unique type of accelerator, which is capable to accelerate kilo-Ampere beam current to tens of MeV. The LIA acceleration modules, filled with ferrite or ferromagnetic toroid cores, can be conveniently stacked to obtain high energy. During the evolution of LIA, several models for the LIA acceleration module and the function of the cores have been proposed. Authors of this paper surveyed these models and tried to bridged them to form a consistent understanding of the LIA acceleration module. The unified understanding should be helpful in the further development and design of the LIA acceleration module.
University of Delhi, Delhi
Fermilab, Batavia
It is well known that insertion of a coupler into a RF cavity breaks the rotational symmetry of the cavity, resulting in an asymmetric field. This asymmetric field results in a transverse RF Kick. This RF kick transversely offsets the bunch from the nominal axis & it depends on the longitudinal position of the particle in the bunch. Also, insertion of coupler generates short range transverse wake field which is independent from the transverse offset of the particle. These effects cause emittance dilution and it is thus important to study their behavior & possible correction mechanisms. These coupler effects, i.e. coupler's RF kick & coupler's wake field are implemented in a beam dynamics program, Lucretia. Simulations are performed for main linac & bunch compressor of International Linear Collider (ILC) like lattices. Results are compared with Placet results & a good agreement has been achieved.
KURRI, Osaka
The acceleration of intense muon beams up to 25 GeV is the challenge of the international design work for a future neutrino factory. The present baseline scenario for muon acceleration is based on linacs, recirculating linear accelerators (RLAs) and non-scaling fixed field alternating gradient (FFAG) rings. However RLAs are one of the most cost driving part. Two new approaches to use zero-chromatic FFAG instead of RLA have been proposed. Detailed lattices parameters and 6D tracking results are presented.
Imperial College of Science and Technology, Department of Physics, London
JLAB, Newport News, Virginia
Within the Neutrino Factory Project the muon acceleration process involves a complex chain of accelerators including a (single-pass) linac, two recirculating linacs and an FFAG. The linac consists of RF cavities and iron shielded solenoids for transverse focusing and has been previously designed relying on idealized field models. However, to predict accurately the transport and acceleration of a high emittance 30 cm wide beam with 10 % energy spread requires detailed knowledge of fringe field distributions. This article presents results of the front-to-end tracking of the muon beam through numerically simulated realistic field distributions for the shielded solenoids and the RF fields. Real and phase space evolution of the beam has been studied along the linac and the results will be presented and discussed.
BNL, Upton, Long Island, New York
Polarized proton beams are accelerated in RHIC to 250 GeV energy with the help of Siberian Snakes. The pair of Siberian Snakes in each RHIC ring holds the design spin tune at 1/2 to avoid polarization loss during acceleration. However, in the presence of closed orbit errors, the actual spin tune can be shifted from the exact 1/2 value. It leads to corresponding shift of locations of higher-order ("Snake") resonances and limits available betatron tune space. The largest closed orbit effect on the spin tune comes from the horizontal orbit angle between the two snakes. During RHIC Run in 2009 dedicated measurements with polarized proton beams were taken to verify the dependence of the spin tune on the local orbits at the Snakes. The experimental results are presented along with the comparison with analytical predictions.
CERN, Geneva
The CLIC study is a site independent study exploring technological developments to extend linear colliders into the Multi-TeV colliding beam energy range at reasonable cost and power consumption. A conceptual design report (CDR) of an electron-positron Compact LInear Collider (CLIC) with a 3 TeV center-of-mass collision energy is presently being prepared including results of 25 years of R&D to address the feasibility of its novel and promising technology, especially in an ambitious Test Facility, CTF3. The R&D is performed by a multi-lateral CLIC/CTF3 collaboration strong of 37 volunteer institutes from 19 countries from which the outstanding work and results are reported.
KIT, Karlsruhe
KCETA, Eggenstein-Leopoldshafen
Cosmic ray particles can produce extended air showers that have a total energy of more than 100 EeV, which is a hundred million times more than the TeV particles that we produce in accelerators. How do the cosmic accelerators work? Where are they and what are they accelerating? How do the supposedly extragalactic particles propagate to Earth? Do they offer a new kind of astronomy? The Pierre Auger Observatory is an international project dedicated to find answers to these - and many more - questions. The presentation reviews the goals, achievements and plans for a better understanding of ultra-high energy cosmic rays.