[en] Status of the KEK TRISTAN project, the Phase I of which has been approved since 1981, is reported with an emphasis on its accelerator design and construction. The design of the accelerator complex has mostly been fixed. Construction of accelerator enclosure and production of accelerator components are under way with a target day for the first e⁺e^- collisions in 1986

[en] KEKB was in operation from December 1988 to June 2010. The crab cavities were installed at KEKB in February 2007 and worked very stably until the end of KEKB operation. Operational experience of the crab cavities with beams is described

[en] Various diagnostic devices have been built and used to measure the properties of the KEK preinjector beams. The mechanical and electronic design and characteristics of the current transformers, Faraday cups, fluorescent scureen and three kinds of emittance probes are described. (author)

[en] In the KEK B-Factory plan, e+/e- collider rings with 3.5- GeV positions and 8-GeV electrons are being considered, and full-energy injection from the existing linac is required. The acceleration energy of the linac must be upgraded from 2.5 to 8 GeV. The most effective way has been searched from several points of view, such as the beam quality, ease of beam handling, and construction. This article describes the basic plan of the energy upgrade and recent progress regarding this project

[en] A high gradient accelerating column was constructed for a preinjector of a 20 MeV proton linac. The column consists of two big porcelain tubes with a two gap accelerating system. The overall gap length is 22 cm. The column ensures a clean vacuum and has sufficient strength because there is no bonding with any organic adhesive. To prevent breakdown, the operating pressure is kept at several times 10^-4 Torr in the column. (author)

[en] High voltage apparatus of the KEK preinjector are briefly reviewed. Intensity modulation or noise of the accelerated beam was eliminated by biasing negatively the plasma cup of the duoplasmatron ion source. Ion beam of 600 mA is accelerated routinely to 750 keV with accelerating gap of 22 cm and 230 mA is injected into the proton linac. Normalized beam emittances are 0.3 approximately 0.5 π cm mrad at the entrance of the linac. Beam loading of the accelerating voltage is more than 15 kV without bouncer and it is compensated to less than 2 kV with bouncer. There is no appreciable change in the energy spread of the linac beam for +-0.5% of injection energies. (author)

[en] A collaboration between KEK and CEBAF is pursuing the development of a superconducting high gradient accelerating structure for application in future accelerator which optimally requires the high field gradient above 25 MV/m. In the first phase of this collaboration three single cell 1300 MHz niobium cavities have been built and tested. In the second phase a full scale 9-cell niobium cavities was manufactured. This paper describes the fabrication and measurement result of the joint 9-cell Nb cavity

[en] The KEK 40 MeV proton linac comprises a pre-buncher, the first tank (750 keV to 20 MeV), the second tank(20 MeV to 40 MeV) and a de-buncher. As routine operation, negative hydrogen ion (H^-) beams of 5 mA with a beam pulse duration of about 80 μs are accelerated and transported to the Booster Synchrotron. In April 1992 negative deuterium ion (D^-) beams of about 2.5 mA were accelerated under the 4 π-mode operation. At present, in order to accelerate H^- or D^- beams, the accelerating field strength in each of the four cavities and the phase differences between the cavities are manually tuned by watching many beam monitors installed on the transport lines. Operation of the KEK 40 MeV proton linac has therefore not been very easy. An RF control system with a feedback (ALC and PLL) system has thus been developed in order to stabilize the accelerating RF fields and to deal with the acceleration mode, which would be used to select parameters of the accelerating field for the acceleration of various particle beams. This report describes the RF control system under development and the tested results. (Author) 5 refs., 6 figs

[en] In this note, we describe the proposed working parameter set for the KEK-SLAC ILC linear collider and discuss the reasons leading to the values listed; more extensive discussion of the optimization process will be found in subsequent notes. The parameter set is listed in Table 1 and is compared with the JLC 3-97 parameters and the NLC ZDR parameters in Table 2. The new parameter set has an operating plane which ranges from low IP emittances and high luminosity (cases A) to large IP emittances and smaller luminosity (cases C). Over this range, the bunch charge, bunch length, and IP beta functions are varied, however, the parameters have been chosen so that the tolerances on the accelerating structures are roughly constant. The collider must be designed to operate over the entire parameter range. In all cases, the parameters were optimized for 120 Hz operation. The scaling to 150 Hz is straightforward--either the beam parameters are held constant and the luminosity and ac power are increased or there are small reductions in the bunch charge and an ensuing loosening of the tolerances. Similarly, scaling to 100 Hz operation is also possible, although, if one wants to maintain the luminosity in this case, the bunch charge must be increased and the beamstrahlung energy loss increases to as much as 15%. In arriving at the parameters, most of the emphasis has been on cost reduction. Thus, at times, we have sacrificed the rf and ac efficiency to obtain a situation that requires fewer rf power sources or significantly looser tolerances; this will be discussed further below. The other issues considered in the parameter determination include: the bunch spacing and beam pulse length limits, the rf structure length, the iris radii (α/λ), and the upgrade path from 500 GeV to 1 TeV cms; each of these issues will be discussed further subsequently

[en] The authors have performed a simulation study on beam bunching in the KEK 2.5-GeV linac new pre-injector comprising double prebunchers and a buncher. Dependence of the bunching performance upon the rf powers and the phases of the prebunchers is discussed. They obtained an optimum bunch length of 4 ps with the simulation