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ABSTRACT: A new laser-based alignment system for the precise alignment of accelerator components along an ideal straight line at the KEK B-factory injector linear accelerator (linac) is under development. This system is strongly required in the next generation of B-factories for the stable acceleration of high-brightness electron and positron beams with high bunch charges and also for maintaining the stability of injection beams with high quality. A new laser optics for the generation of a so-called Airy beam has been developed for the laser-based alignment system. The laser propagation characteristics both in vacuum and at atmospheric pressure have been systematically investigated in an 82-m-long straight section of the injector linac. The laser-based alignment measurements based on the new laser optics have been carried out with a measurement resolution of ±0.1 mm level by using an existing laser detection electronics. The horizontal and vertical displacements from a reference laser line measured using this system are in good agreement with those measured using a standard telescope-based optical alignment technique. In this report, we describe the experimental study in detail along with the basic designs and the recent developments in the new laser-based alignment system.
The Review of scientific instruments 12/2010; 81(12):123301. · 1.52 Impact Factor
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[show abstract]
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ABSTRACT: A new beam-charge interlock system is under development for radiation safety and machine protection at the KEKB injector linac. A hardware-based interlock system is required instead of the present software-based interlock system in order to boost its reliability. This system restricts the integrated amount of beam charges delivered to four different storage rings. The beam charges are measured using wall-current monitors and detection electronics at six locations along the linac. The detection electronics independently transmits a beam-abort request through a twisted hardwire cable directly to the safety control system of the linac, when the integrated amount of beam charges exceeds a certain threshold level prescribed for each location. We describe the characteristics and performance of the new beam-charge interlock system along with the details of the experimental tests.
Review of Scientific Instruments 03/2008; · 1.37 Impact Factor
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T. Suwada, M. Satoh,
T. Sugimura,
T. Kamitani,
K. Furukawa,
K. Umemori,
H. Okuno,
T. Haruna,
R. Hamatsu,
T. Sumiyoshi,
A.P. Potylitsin,
I.S. Tropin,
R. Chehab
[show abstract]
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ABSTRACT: A new tungsten single-crystal target has been successfully employed at the positron source of the KEKB injector linac. The crystal thickness was determined to be 10.5 mm based on the previous systematic measurements of the positron-production efficiency. The crystal axis, lang111rang, was precisely aligned to the direction of the 4-GeV primary electron beam. The positron yield increased by ~25% compared to that for a conventional tungsten plate with a thickness of 14 mm. On the contrary, the heat load on the crystal target decreased by ~20%. No degradation of the positron-production efficiency was observed since the crystal target was installed in September 2006, and it has been stably operating at the KEK B-factory.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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T. Abe,
T. Agho,
K. Akai,
M. Akemoto,
A. Akiyama,
M. Arinaga,
K. Ebihara,
K. Egawa,
A. Enomoto,
J. Flanagan, [......],
S. Uehara,
S. Uno,
Y. Yamamoto,
Y. Yano,
K. Yokoyama,
M. Yoshida,
S. Yoshimoto,
K. Yoshino,
E. Perevedentsev,
D.N. Shatilov
[show abstract]
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ABSTRACT: KEKB has been operating with crab cavities for the first time in the world. This paper represents beam operation with the crab crossing.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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T. Abe,
K. Akai,
M. Akemoto,
A. Akiyama,
M. Arinaga,
K. Ebihara,
K. Egawa,
A. Enomoto,
J. Flanagan,
S. Fukuda, [......],
S. Uehara,
S. Uno,
Y. Yamamoto,
Y. Yano,
K. Yokoyama,
M. Yoshida,
S. Yoshimoto,
K. Yoshino,
E. Perevedentsev,
D.N. Shatilov
[show abstract]
[hide abstract]
ABSTRACT: Crab cavities have been installed in the KEKB B-factory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the prediction of simulation.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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T. Kasuga,
T. Agoh,
A. Enomoto,
S. Fukuda,
K. Furukawa,
T. Furuya,
K. Haga,
K. Harada,
S. Hiramatsu,
T. Honda, [......],
N. Nakamura,
H. Sakai,
T. Shibuya,
K. Shinoe,
H. Takaki,
M. Katoh,
A. Mochihashi,
M. Shimada,
H. Hanaki,
H. Tomizawa
[show abstract]
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ABSTRACT: The energy recovery linac is a very promising synchrotron light source in future. We are contemplating to realize a ERL_based next generation light source in Japan, under a collaboration between KEK, JAEA, ISSP, and other SR institutes. To this end, we started R&D efforts on its key technologies, including a low-emittance photocathode gun and superconducting cavities. We also plan to assemble these technologies into a small test ERL, and to demonstrate their operations. We report our R&D status.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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T Abe,
K. Akai,
M. Akemoto,
A Akiyama,
M. Arinaga,
K Ebihara,
K Egawa,
A Enomoto,
J. Flanagan,
S Fukuda, [......],
Ma. Yoshida,
Mi. Yoshida,
S Yoshimoto,
K Yoshino,
KEK,
Oho,
Tsukuba,
E. Perevedentsev,
D. N. Shatilov,
BINP
[show abstract]
[hide abstract]
ABSTRACT: Crab cavities have been installed in the KEKB B--Factory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the prediction of simulation.
07/2007;
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T. Miyajima,
S. Adachi,
W. X. Cheng,
K. Haga,
K. Harada,
Y. Hori,
K. Hyodo,
T. Ieiri,
S. Isagawa,
T. Kageyama, [......],
T. Takahashi,
S. Takasaki,
Y. Tanimoto,
M. Tejima,
K. Tsuchiya,
T. Uchiyama,
A. Ueda,
K. Umemori,
S. Yamamoto,
S. Yoshimoto
[show abstract]
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ABSTRACT: The Photon Factory Advanced Ring (PF‐AR) is a 6.5‐GeV synchrotron light source at the High Energy Accelerator Research Organization (KEK). It can provide high‐flux hard X‐rays for such research as the materials science, structural biology and medical applications. The PF‐AR has five insertion devices including four in‐vacuum undulators. It is operated with a single bunch which fits for time‐resolved experiments. A special 5‐GeV operation is partly provided for a clinical application. An initial beam current and a beam lifetime are 60 mA and approximately 14 hours, respectively. Recent developments include an installation of a new in‐vacuum undulator (U#NW14‐36) to the west rf section, which was accompanied by transferring two rf cavities to other section. The undulator has been successfully operated at a minimum magnetic gap of 10 mm. We also carried out such accelerator studies as a successful test of beam injection using a pulsed quadrupole magnet, a study of low emittance optics, an establishment of two‐bunch operation for the clinical application, a successful operation of a multi‐bunch feedback system, and an installation of a test undulator which enables us to control polarization using a new arrangement of magnets. © 2007 American Institute of Physics
AIP Conference Proceedings. 01/2007; 879(1):91-94.
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ABSTRACT: We investigated the reliability of MgO and AlO<sub>x</sub> tunneling barrier, for MRAM device. It is found that MgO tunneling barrier has the hydrogen tolerance compared with AlO<sub>x</sub> tunneling barrier. It also demonstrated that MgO-barrier MTJ has longer lifetime, over 10 years, than AlO<sub>x</sub>-barrier MTJ by TDDB data
Reliability Physics Symposium Proceedings, 2006. 44th Annual., IEEE International; 04/2006
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ABSTRACT: The reststrahlen spectra of single-crystal NiO are measured at various temperatures from 300 to 1273 K in the spectral region from 250 to 700 cm−1 by the thermal-emission and reflection method for the first time. Remarkable changes are observed in the reststrahlen band with increasing temperatures. The spectra are analysed by means of the two-oscillator dispersion model, and the temperature dependence of the dispersion parameters is determined. These results are discussed in the light of the theory on anharmonic crystals. The anharmonic phonon-frequency shift is seen to become prominent with increasing temperatures. Appearance of the high-frequency sideband is ascribed to a process involving multi-phonons through the intermediate virtual excitation of the TO-phonon near the center of the Brillouin zone.Die Restrahlenspektren von einkristallinem NiO werden bei verschiedenen Temperaturen von 300 bis 1273 K im spektralen Bereich von 250 bis 700 cm−1 mit einer Thermoemissions-Methode und einer Reflexions-Methode gemessen. Merkliche Veränderungen mit steigender Temperatur werden in der Restrahlen-Bande beobachtet. Die Spektren werden mit einem Dispersions-Modell zweier Oszillatoren analysiert, und die Temperaturabhängigkeit der Dispersions-Parameter werden bestimmt. Diese Resultate werden mit der Theorie anharmonischer Kristalle diskutiert. Es wird gefunden, daß die anharmonische Phononenfrequenzverschiebung mit zunehmender Temperatur bedeutend wird. Das Auftreten der Hochfrequenz-Seitenbande rührt von einem Multiphonon-Prozeß mittels virtuelle Anregung des TO-Phonons nahe dem Zentrum der Brillouin-Zone her.
physica status solidi (b) 02/2006; 106(2):667 - 674. · 1.32 Impact Factor
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ABSTRACT: Some feedback loops are needed to perform the stable beam operation in the long term. The beam orbit and energy feedback loops are widely used for the linac beam operations of many facilities. In addition, the beam energy spread control is also effective for the stable beam operation. In order to realize the energy-spread feedback, the non-destructive beam-energy-spread monitor (ESM) has been developed for the KEKB injector linac. This monitor is an ordinary strip-line type beam monitor with eight electrodes instead of four electrodes. Three EMSs have been installed in the KEKB injector linac for a regular energy-spread measurement. One of them is used for the energy-spread feedback operation. This system works well. In this paper, we will present the energy-spread feedback system for the KEKB injector linac in detail.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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T. Miyajima,
T. Abe,
K. Ebihara,
K. Haga,
K. Harada,
Y. Hori,
T. Ieiri,
S. Isagawa,
T. Kageyama,
T. Kasuga, [......],
Y. Tanimoto,
M. Tejima,
K. Tsuchiya,
T. Uchiyama,
A. Ueda,
K. Umemori,
C. Weixing,
N. Yamamoto,
S. Yamamoto,
S. Yoshimoto
[show abstract]
[hide abstract]
ABSTRACT: The Photon Factory Advanced Ring (PF-AR) is a synchrotron light source dedicated to X-ray research. Although the PF-AR is usually operated at a stored beam energy of 6.5 GeV, a 5.0 GeV mode is also available for medical application. In the 6.5 GeV mode, the beam current of 60 mA in a single-bunch and the typical lifetime of 15 hrs at the current have been archived. Single-bunch operation for pulsed X-ray and its relatively high beam energy characterize the PF-AR. However, the high-current in single-bunch causes several problems to be solved, such as the temperature rise of some of the vacuum components, a pressure increase in the ring, and a sudden drop of beam lifetime. In order to avoid these problems, developments of new methods have been continued. In this paper, the status and the recent developments of the PF-AR are presented. It concerns: the successful operation with a two-bunch high-current operation at 5.0 GeV; the vertical beam size control for the medical application; modulating the RF acceleration phase in order to elongate the bunch length; stabilizing temperature in the ring tunnel; the study for medium emittance operation with 160 nm · rad; transferring the RF cavities in order to install a new insertion device; an innovative injection scheme using a pulsed quadrupole magnet.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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T. Abe,
K. Ebihara,
E. Ezura,
K. Haga,
K. Harada,
Y. Hori,
T. Ieiri,
S. Isagawa,
T. Kageyama,
T. Kasuga, [......],
M. Tejima,
K. Tsuchiya,
T. Uchiyama,
A. Ueda,
K. Umemori,
N. Yamamoto,
S. Yamamoto,
S. Yoshimoto,
M. Yoshioka,
T. Fujita
[show abstract]
[hide abstract]
ABSTRACT: The PF‐AR is a full‐time single‐bunch light source for SR experiments in the X‐ray region. Electrons are injected at 3.0 GeV and ramped up to the final energy of 6.5 GeV for normal user operation or 5.0 GeV for medical application. The typical initial beam current is 55 mA at 6.5 GeV and the beam lifetime is 15 h at 50 mA. The initial single‐bunch impurity better than 10−8 was achieved, however, degradation of the impurity during the users’ run has to be solved. Since the present emittance of 290nm⋅rad is not satisfactory, we are making an effort to realize the minimum attainable emittance of 160nm⋅rad. The high quality of pulse X‐ray has brought us abundant occasions to do time‐domain and/or time‐resolved measurements. © 2004 American Institute of Physics
AIP Conference Proceedings. 05/2004; 705(1):33-36.
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Biopolymers 01/2004; 21(9):1927 - 1931. · 2.87 Impact Factor
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ABSTRACT: In the KEKB injector linac, a two-bunch acceleration scheme has been used for doubling the positron injection rate to the KEKB low-energy-ring (LER). In this operation mode, the multi-bunch transverse wake field caused by the first bunch affects the beam orbit of the second bunch. In the KEKB linac, an orbit correction method based on the average minimum of two-bunch orbits has been adopted, and has worked stably. However, a new two-bunch orbit correction method is strongly required to make the loss of charge less. We propose a new two-bunch orbit correction method based on a local bump method. In this scheme, some local bumps are intentionally constructed in a low-energy area. Adjusting the local bump height can control the wake field strength affecting the second bunch. In this paper, we report on the results of a preliminary beam test to confirm that this new method is useful
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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T. Miyajima,
K. Ebihara,
E. Ezura,
H. Fukuma,
K. Haga,
K. Harada,
Y. Hori,
T. Ieiri,
S. Isagawa,
T. Kasuga, [......],
M. Tejima,
K. Tsuchiya,
T. Uchiyama,
A. Ueda,
K. Umemori,
N. Yamamoto,
S. Yamamoto,
S. Yoshimoto,
M. Yoshioka,
T. Fujita
[show abstract]
[hide abstract]
ABSTRACT: The upgrade project of the pulse X-ray source PF-AR was successfully completed by the end of 2001. The initial beam current and the lifetime were largely improved. The injection energy was raised from 2.5 GeV to 3.0 GeV, the maximum beam current of 65 mA was achieved. With a new global orbit feedback system, orbit drifts were largely improved.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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ABSTRACT: A nondestructive beam-energy-spread monitor (BESM) using multi-stripline electrodes has been newly developed in order to measure and control the energy spread of a single-bunch electron beam at the 180-degree arc with a beam energy of 1.7 GeV in the KEKB injector linac. A proof-of-principle experiment was performed to verify the function of the BESM. The result shows that taking into account the second-order moment derived from the multipole-moment analysis, the energy spreads are estimated to be 0.150 ± 0.007% and 0.264 ± 0.004% for the electron beams with charges of 0.9 and 8 nC/bunch at the rf phase of the energy-spread minimum, respectively.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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M. Satoh,
K. Iida,
K. Harada,
H. Takaki,
T. Koseki,
N. Nakamura,
T. Sakai,
K. Ishiwata,
K. Yokoyama,
Y. Hayakawa,
K. Hayakawa,
T. Tanaka,
I. Sato,
S. Miura,
T. Matsumoto,
T. Shidara,
S. Fukuda,
H. Kobayashi,
Y. Kamiya
[show abstract]
[hide abstract]
ABSTRACT: The initial beam loading effect may cause serious beam loss in the
electron linac of the Super SOR light source. Because of the large
energy spread, it is difficult to compensate the beam loading with
ordinary methods, such as the adjustment of injection timing and the ECS
(Energy Compensation System). A phase-amplitude (Δφ-A)
modulation system has already been developed and tested. A first beam
test using this system was carried out at the 125MeV electron linac of
the Laboratory for Electron Beam Research and Application (LEBRA) in
Nihon University. The result shows that our system corrects well the
energy spread due to the initial beam loading effect. In this paper, we
report the results of first beam test
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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[show abstract]
[hide abstract]
ABSTRACT: The authors have studied the microwave properties of high- T
<sub>c</sub> superconducting EuBa<sub>2</sub>Cu<sub>3</sub>O<sub>y
</sub> (EBCO) films on MgO and YAlO<sub>3</sub> substrates with low
dielectric constants (∈=10 and 16, respectively), and a low loss
tangent (tanδ <10<sup>-5</sup>). Measurements of surface
resistance R <sub>s</sub> at 50 GHz in a cavity show that EBCO
films exhibit low R <sub>s</sub> values (77 K) of 2-10 mΩ.
A microstructural study using transmission electron microscopy showed
that crystal defects related to the in-plane misorientation are observed
for films with higher R <sub>s</sub> values. The
R <sub>s</sub> values of the patterned films were measured in a
coplanar transmission line resonator. A typical value for patterned
films was 28 μΩ at 4 GHz and 28 K
IEEE Transactions on Appiled Superconductivity 04/1993; · 1.04 Impact Factor
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[hide abstract]
ABSTRACT: An active suspension employing an electrohydraulic servosystem in
which pressure control valves are applied for the first time has been
developed. The suspension is controlled by a microprocessor and
acceleration sensors. The authors describe the theoretical and
experimental analyses that were conducted in developing this system,
including the studies of the active control system, vehicle system
dynamics, and transmission of vertical inputs from the road surface.
This system features a skyhook damper which can reduce body vibration to
less than one-half that of conventional suspensions at low frequencies
by applying an active damping force to the body proportional to its
absolute velocity. The hydraulic system has passive damping
characteristics dependent on the frequencies of road inputs.
Optimization of these characteristics results in a reduction of
vibration caused by high-frequency road surface inputs. An active moment
control function using lateral and longitudinal sensors which can reduce
body pitching and rolling is provided
Decision and Control, 1990., Proceedings of the 29th IEEE Conference on; 01/1991
