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| TUPMY002 | APF IH-DTL Design for the Muon LINAC in the J-PARC Muon g-2/EDM Experiment | 1539 |
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| The muon linac for the J-PARC muon g-2/EDM experiment consists of RFQ (324 MHz), IH-DTL (324 MHz), DAW coupled cell linac (1.3 GHz), and disk loaded structure (1.3 GHz). Because muon has finite life time, the muons should be accelerated in a sufficiently short period. To realize fast acceleration, Alternative Phase Focusing (APF) scheme is adopted in IH-DTL in which the muons are accelerated from 0.34 MeV to about 4 MeV. In this poster, the design of the APF IH-DTL for muon acceleraiton with the computer calculation will be presented. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY002 | |
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| TUPMY003 | Development of Muon LINAC for the Muon g-2/EDM Experiment at J-PARC | 1543 |
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| Precision measurements of the muon's anomalous magnetic moment (g-2) and electric dipole moment (EDM) are effective ways to cast light on beyond the standard model of elementary particle physics. The J-PARC E34 experiment aims to measure g-2 with a precision of 0.1 ppm and search for EDM with a sensitivity to 10-{-21} e· cm with high intensity proton beam at J-PARC and a novel technique of making a muon beam with small emittance (the ultra-cold muon beam). The ultra-cold muon beam is generated from a surface muon beam by the thermal muonium (30 meV) production followed by the laser ionization, and acceleration to 212 MeV or 300 MeV/c by the muon dedicated LINAC. The muon LINAC consists of RFQ, inter-digital IH, Disk And Washer (DAW) coupled cell and disk loaded structure. The ultra-cold muons will have an extremely small transverse momentum spread of less than 1 % with a normalized transverse emittance of around 1.5 pi mm-mrad. The muon acceleration to 300 MeV/c will be the first case in the world and it will be one of the base technologies of future accelerator programs. In this talk, design and status of the muon LINAC will be reported. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY003 | |
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| TUPMY017 | Laser Driven Dielectric Accelerator in the Non-relativistic Energy Region | 1585 |
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| Laser-driven dielectric accelerator (LDA) is suitable for delivering a submicron-size ultra-short electron beam, which is useful for studying basic processes of the radiation effect in a biological cell. Both the oblique incidence and the normal incidence configurations of LDA were studied. The oblique incidence configuration of LDA relaxes the synchronization condition as ve=¥pm c LG/¥left(¥λ+ LG n ¥sin ¥theta ¥right) and is somewhat suitable for accelerating the non-relativistic electrons. The required energy to accelerate electrons in the oblique incidence configuration is smaller than that in the normal incidence configuration by a factor of ¥cos ¥theta, where ¥theta is the incidence angle of the laser beam. Two gratings each were made of different material structure of silica ({¥rm SiO2}) were fabricated by the electron beam lithography. When a crystal silica was adopted, many large humps of several hundred nm size were observed in grooves of the grating. On the other hand, a glass silica had smoother grooves. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY017 | |
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| TUPOW036 | Recent Developments and Operational Status of the Compact ERL at KEK | 1835 |
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| The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator in order to develop key components to realize remarkable ERL performance as a future light source. After the beam commissioning in December 2013, the legal current limit has been increased step-by-step like 1 uA, 10 uA, and 100 uA. Survey for the source of beam losses has been conducted in each step, and the study on beam dynamics and tuning has also been carried out. As a next step, 1 mA operation is scheduled in February 2016. In parallel to the increase in beam current, a laser Compton scattering (LCS) system which can provide high-flux X-ray to a beamline has been successfully commissioned. We report recent progress in various kinds of beam tuning: improvement of electron gun performance, high bunch charge operation, mitigation of beam losses, LCS optics tuning and bunch compression for THz radiation. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW036 | |
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| WEPMY037 | Cold Model Cavity for 20-K Cryocooled C-band Photocathode RF Gun | 2635 |
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Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). A cryocooled 2.6-cell C-band photocathode RF gun is under development at Nihon University in collaboration with KEK. The RF characteristics of a pillbox-type 2.6-cell C-band RF cavity at 20 K were in agreement with the theoretical predictions. The result of the cold test for a cavity with the input coupler confirmed the same characteristics. Based on these results a refined cold model of the 20-K cryocooled photocathode RF gun has been designed using SUPERFISH and CST-STUDIO. The separation between the TM01 pi and the TM01 half-pi modes has been increased from 20 MHz to 52 MHz by extending the diameter of the cavity iris and reducing the disk thickness. The 2.6-cell structure has been modified from pillbox to ellipsoid-like type. The end-plate of the 0.6-cell cavity has a center hole for bead-pull measurements of the on-axis electric filed through the entire structure. Mounting of a photocathode assembly in the end-plate has not been considered, since the purpose is solely to measure the low-power and low-temperature RF characteristics. A new design for the input coupler has been employed. The cavity will be completed early in 2016. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY037 | |
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| WEPMY038 | Optimization of C-band RF Input Coupler as a Mode Converter for 20-K Cryocooled Photocathode RF Gun | 2638 |
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Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). Development of a cryocooled 2.6-cell C-band photocathode RF gun has been conducted at Nihon University in collaboration with KEK. An RF mode converter from square TE10 to circular TM01 mode has been employed as an RF input coupler that has a coupling coefficient of approximately 20 at 20 K to the 2.6-cell accelerating structure. In the previous design, the circular waveguide in the mode converter formed part of the accelerating cavity. After the cold test of the cavity completed in 2014, the coupler design was modified to work as a pure mode converter with a VSWR of 1 at 5712 MHz. From the design simulation using CST-STUDIO, the insertion loss in the converter is 0.2 %. The TM010 and TM011 modes excited in the circular waveguide were separated by several ten MHz from the accelerating frequency. The simulation has suggested that the amplitude of the transverse electric filed on the axis in the circular waveguide is reduced to approximately 2 % of that in the longitudinal direction. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY038 | |
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| WEPMY040 | Fabrication of Two Dimensional Nano-Scale Photocathode Arrays in Transparent Conductor for High Coherence Beam Generation | 2645 |
| SUPSS039 | use link to see paper's listing under its alternate paper code | |
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| Electron beam quality for particle source of diffractometer is mainly characterized by transverse and longitudinal coherent length, beam current density and so on. In order to improve a transverse coherent length, it is practically essential to minimize electrons emission area size as small as possible. However, the size of photoemission area is limited by focused laser beam size on the surface of cathode, and the scale is several microns. Aim to get definite overlap between the focused laser and emitters for effective irradiation, as well as to realize generation of nano-scale size electron beam, nano-scale photocathode arrays in transparent conductor are essential. Therefore, I propose to fabricate the nano-scale emission area in replace of limiting the focused laser size on the photocathode for achieving high coherence beam. The fabrication process of this novel nano-scale emitter configuration and its fundamental properties are presented in this paper. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY040 | |
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| THPMY041 | Neodymium and Ytterbium Hybrid Solid Laser of RF Gun for SuperKEKB | 3748 |
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| The electrum beam of the repetition rate of 50 Hz double-bunch is requested for injector linac of SuperKEKB. By development of the Yb-doped laser system, more than 5.0 nC and 3.0 nC electron beam with single-bunch has been generated in the 5 Hz and 25 Hz respectively. Also more than 1.0 nC electron with double-bunch has been obtained in 25 Hz. The Yb-doped laser system is already for commissioning for the linac. Next, a new laser system is development to improve the stability and reliability. The laser system starts with a 50 MHz Yb-doped fiber oscillator with the all normal dispersion (ANDi) structure. A transmission grating pair stretcher was employed to expend pulse to ~30 ps and separate the pulse to two parts with the center wavelength of 1030 nm and 1064 nm. Then the two kinds of pulses can be amplified by Yb:YAG and Nd:YAG crystals respectively. The weak pulses were amplified by the Yb-doped fiber amplifier, and reduced repetition rate by a semiconductor optics amplifier (SOA) pulse picker. To obtain the mJ-class pulse energy, a Yb:YAG thin-disk regenerative solid-state amplifier and a Nd:YAG rod regenerative solid-state amplifier were employed. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY041 | |
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| THPOW056 | Fiber Laser Development for Dielectric Laser-driven Accelerator and Electron Beam Source | 4070 |
| SUPSS024 | use link to see paper's listing under its alternate paper code | |
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Our group is aiming for developing a table-top electronμbeam source, whose beam size is micro-meter order so that we can irradiate just the nuclei of cells (1μm) and observe the behavior in real time. This beam source will be realized by dielectric laser-driven accelerators(DLAs), which is expected to produce acceleration gradients of ~GV/m. To drive these accelerators, ultra-short pulse laser has to be incident to the structure*. We chose Ytterbium (Yb) fiber laser for generating and amplifying ultra-short laser pulse, which has high quantum efficiency and can easily pumped by LD, and is proper to produce ultra-short pulses because of its wide-band oscillation. We succeeded in getting ultra-short pulse (central wavelength: {1030} nm, average output: 10 W, pulse duration: ~10 ps, reputation rate: 84 MHz) from Yb fiber laser system. Also in order to make electron bunch by photo cathode, we then converted the obtained IR laser to UV of 258 nm (4ω) using BBO and LBO crystals. We are planning to amplify the pulses by Yb:YAG in future, which has its amplification band in {1030} nm.
* K. Koyama el al., "Design Of Photonic Crystal Accelerator For Radiation Biology," IPAC'12 Proceedings (2014) |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW056 | |
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| THPOY027 | Commissioning Status of SuperKEKB Injector Linac | 4152 |
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| The SuperKEKB main ring is currently being constructed for aiming at the peak luminosity of 8 x 1035 cm-2s−1. The electron/positron injector linac upgrade is also going on for increasing the intensity of bunch charge with keeping the small emittance. The key upgrade issues are the construction of positron damping ring, a new positron capture system, and a low emittance photo-cathode rf electron source. The injector linac beam commissioning started in the October of 2013. In this paper, we report the present status and future plan of SuperKEKB injector commissioning. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY027 | |
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