K. Asano

Bio: K. Asano is an academic researcher from KEK. The author has contributed to research in topics: Collider & Laser ablation. The author has an hindex of 2, co-authored 4 publications receiving 31 citations.

Accelerator structure R&D for linear colliders

Abstract: For more than ten years, we have been working on R&D for X-band accelerator structures for the JLC/NLC linear collider. Several types of Detuned (DS) and Damped Detuned Structures (DDS) have been successfully designed and fabricated. They have been experimentally tested at both low power and high power to characterize their mechanical and electrical properties. Recently we started developing a new type of damped detuned structure with optimized round-shaped cavities (RDDS). This paper discusses the special specifications, design methods, fabrication procedures, measurement technologies, and anticipated future improvements for all these structures.

Fabrication of DDS-3, an 11.4 GHz damped-detuned structure

Abstract: A 1.8 m X-band damped-detuned structure (DDS-3) has been fabricated and characterized as part of the structure development program towards a TeV-scale e/sup +/e/sup -/ linear collider. In this joint venture, the Cu cells were precision-fabricated by LLNL, diffusion-bonded into a monolithic structure by KEK, and the structure completed and tested by SLAC. The overall process constitutes a baseline for future high-volume structure manufacture.

Challenge to a straight structure for X-band linear collider

Abstract: The structure of the X-band main linac for the linear collider requires a stringent straightness of the order of several microns Especially the misalignment from cell-to-cell to over twenty cells should be minimized An one-shot diffusion bonding technology has been developed at KEK aiming at this requirement Two 13 m-long detuned structures have been made with a gentle bow of 20 microns Recently the technology was applied to the main body bonding of an 18 m-long damped-detuned structure, DDS3 It resulted in a much larger bow but the cell misalignment showed very smooth behavior and can later be corrected mechanically The technique is being refined to obtain a better performance of the main body of the round DDS structure, RDDS1 In the present paper are described the studies on the basic techniques applied for DDS3

Microwave surface resistance of YBaCuO superconducting films laser-ablated on copper substrates

Abstract: In order to apply high-T/sub c/ material to a real accelerator cavity, it may be indispensable that the material is deposited on metal substrate. It is now possible to align the c axis of YBa/sub 2/Cu/sub 3/O/sub y/ (YBCO) film perpendicular to a metal surface. Furthermore, the constituent crystals can be in-plane aligned with a laser ablation technique following the formation of yttria-stabilized-zirconia (YSZ) buffer layer of controlled grain orientation. Using a demountable copper cavity operated at 13 GHz in the TE/sub 011/ mode, the microwave surface resistance was measured over a temperature range from 11 K to 300 K.

Applications of X-band technology in medical accelerators

Abstract: Most radiation therapy machines are based on microwave linear accelerators. The majority of medical accelerators use frequencies in the S-band range. Having a compact accelerator allows for a wide range of treatments. The size and weight of the accelerator is substantially reduced if a higher frequency is used. X-band frequencies are suitable for such applications. The X-band accelerator technology has been used in high-energy as well as industrial applications. In the radiation therapy field, it is already implemented in some machines. The Mobetron an Intra-Operative Radiation Therapy (IORT) treatment system is one example. Another example is the Stereotactic Radiosurgery machine, the CyberKnife. The compactness of these machines required the use of an X-band accelerator. The basis for choosing the X-band technology in some of the medical machines is analysed. A review of the exiting medical applications is included. We also discuss the availability of other X-band components in the machine, including high-power RF sources.

Progress in the Next Linear Collider Design

Abstract: An electron/positron linear collider with a center-of-mass energy between 0.5 and 1 TeV would be an important complement to the physics program of the LHC. The Next Linear Collider (NLC) is being designed by a US collaboration (FNAL, LBNL, LLNL, and SLAC) which is working closely with the Japanese collaboration that is designing the Japanese Linear Collider (JLC). The NLC main linacs are based on normal conducting 11 GHz rf. This paper will discuss the technical difficulties encountered as well as the many changes that have been made to the NLC design over the last year. These changes include improvements to the X-band rf system as well as modifications to the injector and the beam delivery system. They are based on new conceptual solutions as well as results from the R&D programs which have exceeded initial specifications. The net effect has been to reduce the length of the collider from about 32 km to 25 km and to reduce the number of klystrons and modulators by a factor of two. Together these lead to s...

Conceptual design of an X-FEL facility using CLIC X-band accelerating structure

Abstract: Dogan, Mustafa (Dogus Author) -- Conference full title: 5th International Particle Accelerator Conference, IPAC 2014; International Congress Center DresdenDresden; Germany; 15 June 2014 through 20 June 2014.

Electromagnetic fields in nonuniform disk-loaded waveguides

Abstract: On the base of general approach we obtain some results that can be useful in the process of tuning of nonunifrom disc-loaded waveguides Our consideration has shown that simple values that characterize the detuning of the cells can be introduced only for the disc-loaded waveguide with parameters that change very slow In general case it is needed to conduct full numerical simulation of specific disc-loaded waveguide and obtain all necessary coupling coefficients After that one can start the tuning process on the base of bead-pull field distribution measurements

FEL proposal based on CLIC X-band structure

Abstract: A linear accelerating structure with an average loaded gradient of 100 MV/m at X-Band frequencies has been demonstrated in the CLIC study. Recently, it has been proposed to use this structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by an RF source created by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the structure choice and conceptual design parameters of a facility which could generate laser photon pulses below Angstrom. Shorter wavelengths can also be reached with slightly increasing the energy.