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-ray sourcesHajima, Ryoichi; Ferdows, M.
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1150 - 1152, 2014/07
-ray source at JAEA 150-MeV microtronHajima, Ryoichi; Ferdows, M.; Hayakawa, Takehito; Shizuma, Toshiyuki; Kando, Masaki; Daito, Izuru*; Negm, H.*; Ogaki, Hideaki*
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1943 - 1945, 2014/07
Tamura, Fumihiko; Omori, Chihiro*; Yoshii, Masahito*; Hasegawa, Katsushi*; Paoluzzi, M.*
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.3385 - 3387, 2014/07
In the framework of the LHC Injectors Upgrade project (LIU), a complete replacement of the existing narrow-band rf systems of CERN PS with wide-band magnetic alloy (MA) loaded rf systems is in progress. A single gap MA loaded rf system prototype, which uses solid-state power amplifier and includes fast rf feedback for beam loading compensation, has been installed in the J-PARC MR to investigate the system behavior with high intensity proton beams. We report the wake voltage measurement results with and without fast rf feedback. In addition to the fast feedback, the rf feed forward method is under consideration to compensate the heavy beam loading more effectively. Preliminary beam test results with feed forward are also presented.
Noda, Akira*; Nakao, Masao*; Okamoto, Hiromi*; Osaki, Kazuya*; Yuri, Yosuke; Soda, Hikaru*; Tongu, Hiromu*; Jimbo, Koichi*; Grieser, M.*; He, Z.*; et al.
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.28 - 33, 2014/07
Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Honda, Yosuke*; Kosuge, Atsushi*; Urakawa, Junji*
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1940 - 1942, 2014/07
In order to demonstrate required accelerator and laser technologies for a high intensity -ray source from the laser Compton scattering (LCS), an LCS photon source and the peripheral equipment are under construction at the Compact ERL (cERL) at High Energy Accelerator Research Organization (KEK). The LCS photon source by an electron beam in the energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear species. The LCS photon source and the peripheral equipment consist of a mode-locked fiber laser, laser enhancement cavity, beamline, and experimental hatch. The commissioning of the LCS photon source will be started in February 2015.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.3379 - 3381, 2014/07
Last summer shutdown an injection energy of J-PARC rapid cycling synchrotron was upgraded from 181 MeV to 400 MeV to aim for reduction of the space charge effect during injection period. By the commissioning after the shutdown, 300 kW operation condition was established. In this condition, the doses of most areas were kept at the same level as 181 injection energy operation or decreased except to the injection foil chamber, 100 degrees and H
dumps.
Saha, P. K.; Shobuda, Yoshihiro; Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Tamura, Fumihiko; Yamamoto, Masanobu
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1683 - 1685, 2014/07
Kamiya, Junichiro; Kinsho, Michikazu; Noshiroya, Shiyoji; Yamamoto, Kazami
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2338 - 2340, 2014/07
In high power beam accelerators, pressure of the beam line directly affects the amount of the beam loss. J-PARC RCS is one of the most high power beam accelerators in the world. It aims the 1MW beam power, which corresponds to the average and peak beam current of 333 
A and about 10 A, respectively. In the present stage, the injection line called L3BT line (Linac to 3GeV Beam Transport line), is the section, where the pressure notably produces the beam loss. In this section, H
beam from Linac was converted to H beam by charge stripping due to the interaction between H beam and the residual gas molecules. Such H beam was not bended by the injection septum magnets and directly hit the vacuum wall. We decided to add the vacuum pumps in this section to reduce the residual gas molecules in the beam line. In this paper, we will present the effectivity of the additional pumps by showing the relation between the beam line pressure and beam loss.
Hayashi, Naoki; Hatakeyama, Shuichiro; Yamamoto, Kazami
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.3800 - 3802, 2014/07
The data archive system in the J-PARC 25-Hz Rapid-Cycling Synchrotron (RCS) records the beam intensity and the beam loss monitor (BLM) pattern for all pulses. The system is based on the common memory and utilizes the timing system of the J-PARC. Although its time resolution is limited, it is useful to detect rare events or phenomena appearing with only higher accelerator repetition. Using these data, the stability of the beam intensity, particularly ion source or the relation between BLM patterns and its causes can be studied pulse-by-pulse basis and it would make use of future improvements.
Hotchi, Hideaki; J-PARC Beam Commissioning Team
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.899 - 903, 2014/07
In the summer shutdown of 2013, the output energy of the J-PARC linac was upgraded from 181 MeV to the design value of 400 MeV. With this upgraded injection energy, the following RCS has successfully demonstrated 550-kW high intense acceleration at a low-level beam loss of less than 0.5%. In this paper, we present the outcome of the recent high intensity beam trial performed in the RCS, together with the brief report on the beam commissioning status of the 400-MeV linac.
Kinsho, Michikazu
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.3382 - 3384, 2014/07
Big issue for the J-PARC rapid cycling synchrotron (RCS) was displacement of main magnets caused by last big earthquake because this made beam loss more than 400 kW beam power. Since realignment of main magnets and other components was essential to realize higher beam power and stable operation, this work has been done during maintenance period in 2013. To achieve the nominal performance 1MW beam power at the RCS and 0.75 MW at the MR, beam energy of linac was increased from 181 MeV to 400 MeV with a new accelerating structure ACS (Annular-ring Coupled Structure) linac from this January. It was successful 400 MeV beam injection and 3 GeV beam extraction at the RCS, and user operation has been performed with beam power of 300 kW. An equivalent beam power of 560 kW with a beam loss of only 0.3% could be achieved during short time for high intensity beam study.
beam halo scraper system in the J-PARC L3BTOkabe, Kota; Yamamoto, Kazami; Yoshimoto, Masahiro; Kinsho, Michikazu
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.876 - 878, 2014/07
In the Japan Proton Accelerator Research Complex (J-PARC) 3-GeV rapid cycle synchrotron (RCS), transverse beam halo scraping for the injection beam is required to increase the output beam power. The transverse scraper system at the Linac-RCS beam transport line (L3BT) was utilized in a nominal beam operation because the area of the scraper section was contaminated when the scrapers were working. In the summer-autumn period of 2013, we installed the new beam-halo scrapers which had optimized scraper heads for mitigation of the radiation around the scraper system. In this paper, we report a preliminary result for a halo scraper at the L3BT.
Sawamura, Masaru; Hajima, Ryoichi; Nagai, Ryoji; Kubo, Takayuki*; Fujisawa, Hiroshi*; Iwashita, Yoshihisa*; Tongu, Hiromu*
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1946 - 1948, 2014/07
We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and -ray sources in academic and industrial applications, we adopt 325-MHz super-conducting spoke cavity to electron beam drivers. The spoke cavity, originally invented for ion and proton acceleration, can be used for electron accelerators, in which we can make best use of features of spoke cavity: relative compactness in comparison with a TM cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, couplers on outer conductor for the better packing in a linac, and so on. In this paper, we present our research plan and results of cavity shape optimization.
Sakai, Hiroshi*; Enami, Kazuhiro*; Furuya, Takaaki*; Sato, Masato*; Shinoe, Kenji*; Umemori, Kensei*; Sawamura, Masaru; Cenni, E.*; Aoto, Tomohiro*; Hayashi, Kyohei*; et al.
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1787 - 1789, 2014/07
Alignment of superconducting cavities is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to liquid He temperature more precisely, we newly developed the position monitor based on the measurement of the interference of light between the measurement target and the reference point. We applied this monitor to the main linac cryomodule of Compact ERL (cERL) and successfully measured the displacement during 2 K cooling with the resolution of 10 m.
Sato, Masato*; Enami, Kazuhiro*; Furuya, Takaaki*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Sakai, Hiroshi*; Shinoe, Kenji*; Umemori, Kensei*; Sawamura, Masaru; et al.
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2531 - 2533, 2014/07
For the main linac of ERL, high loaded Q (QL) operation is desirable to reduce the input generator power. In such operation mode, the suppression of the micophonics is important to stabilize RF amplitude and phase. One of reasons which causes microphonics is mechanical vibration, which changes the cavity frequency. The vibrations of the cavities, the cryomodule and the floor were investigated and compared with the microphnics data taken during cERL operation.
Enami, Kazuhiro*; Furuya, Takaaki*; Sakai, Hiroshi*; Sato, Masato*; Shinoe, Kenji*; Umemori, Kensei*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Arakawa, Dai*; et al.
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2534 - 2536, 2014/07
We evaluated a slidejack tuner adopted as compact ERL Main Linac tuner. The tuner compensates the frequency by extending a cavity. Tuning is driven by two system, piezo and slidejack system. Slide-jack mechanism with long stroke drives coarsely piezo adjust precisely and fast. We tested performance of the tuners on operation.
Iwashita, Yoshihisa*; Fujisawa, Hiroshi*; Tongu, Hiromu*; Hajima, Ryoichi; Nagai, Ryoji; Sawamura, Masaru; Kubo, Takayuki*
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2543 - 2545, 2014/07
Superconducting spoke cavities for laser Compton scattered (LCS) photon sources is under development. The operating frequency is 325-MHz to accelerate electron beam for the LCS sources, where the size of the spoke cavity is less than an elliptical cavities with the same frequency. Because of the complicated shape of the cavity, it may be suffered from a strong multipactor effect. Some trial of multipactor analysis is described.
Umemori, Kensei*; Enami, Kazuhiro*; Furuya, Takaaki*; Michizono, Shinichiro*; Miura, Takako*; Qiu, F.*; Sakai, Hiroshi*; Sato, Masato*; Shinoe, Kenji*; Sawamura, Masaru; et al.
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2537 - 2539, 2014/07
We developed ERL main linac cryomodule for Compact ERL (cERL) project, which was constructed in KEK. The module includes two 9-cell L-band superconducting cavities. After construction of cERL recirculation loop, beam operation was started. First electron beam successfully passed the main linac cavities. After adjusting beam optics, energy recovery operation was achieved. Main linac cavity was enough stable for ERL beam operation, however, field emission was a problem for long term operation.
