KEK, Ibaraki
SLAC, Menlo Park, California
Fermilab, Batavia
INFN/LASA, Segrate (MI)
DESY, Hamburg
In an attempt at demonstrating an average field gradient of 31.5 MV/m as per the design accelerating gradient for ILC, a program called S1-Global is in progress as an international research collaboration among KEK, INFN, FNAL, DESY and SLAC. The design of the S1-G cryomodule began at May 2008 by INFN and KEK. The S1-Global cryomodule was designed to contain eight superconducting cavities from FNAL, DESY and KEK, and to be constructed by joining two half-size cryomodules, each 6 m in length. The module containing four cavities from FNAL and DESY was constructed by INFN. Four KEK cavities have been assembled in the 6 m module which KEK fabricated. All major components were transported to KEK from INFN, FNAL and DESY in December 2009. The assembly of the two 6-m cryomodules started from January 2010 in a collaborative work of FNAL, DESY, INFN and KEK. The construction of the S1-G cryomodule will complete in May, and the cool-down of the S1-G cryomodule is scheduled from June 2010 at the KEK-STF. In this paper, the construction and the cold tests of the S1-Global cryomodule in the worldwide research collaboration will be presented.
KEK, Ibaraki
The KEKB-factory will be upgraded for 40 times higher lumnosity (SuperKEKB). The injector linac is required to increase the beam intensities (e-:1nC -> 5nC, e-:1nC -> 4nC) and reduce the emittances (e-:300 -> 20 um, e+: 2100 -> 10 um ) for the SuperKEKB. A photo-cathode RF gun will be introduced to generate the high-intensity and low-emittance electron beams. A positron damping ring will be constructed to reduce the emittance. A new matching device (a flux concentrator or a superconducing magnet) and an L-band capture section will be introduced to increase the positron intensity. Beam line layout down to the damping ring will be rearranged to have sufficient beam acceptance considering the positron emitttance. This paper describes details of the upgrade scheme of the injector linac.
KEK, Ibaraki
Distributed RF Scheme (DRFS) was proposed for International Linear Collider (ILC) as a new HLRF scheme. After the ITRP recommendation, ILC technology was chosen to be superconducting technology and basic design was discussed and reported in the RDR on 2007. Aiming for the cost reduction, there have been proposed many ideas and summarized as SB2009 proposal. DRFS is the one of these proposals, and it is linked to the single tunnel plan. DRFS employs many small klystrons (750kW output power) which feed power to two superconducting cavities. 13 modulating anode klystrons are operated by a DC power supply and a modulating anode pulser. All required components are installed in a tunnel and therefore this scheme is a complete single tunnel layout. DRFS was proposed in 2008 and thereafter it has been discussed in web-ex meeting and GDE workshop. In this conference, concept and detailed design of DRFS are presented including the availability and operability. In order to show the feasibility of DRFS, KEK has a plan of demonstration employing the DRFS with two klystrons in the S1 global in the end of 2010. Presenter also discussed pros and cons comparing with the competing proposed scheme.
KEK, Ibaraki
The international linear collider (ILC) project is about to meet the technical design phase 2, of which the goal is to establish a realistic design by the end of 2012. Single-tunnel accelerator configuration is one of the most essential improvements to reduce the construction costs. The original design involves two tunnels which house the accelerator cavities and the power supplies separately, having such advantages as we can enter the power-supply tunnel even during beam operation. Although the single tunnel configuration sacrifices these functions, it saves big tunnel construction costs. The Asian team is studying a regional single-tunnel accelerator configuration to match the Asian site feature in conjunction with a compact high-level RF scheme called distributed RF system (DRFS). The design concepts have been developed by a conventional facility working group in the advanced accelerator association (AAA) which involves a collaboration among academic, industrial, and political communities in Japan. Not only cost reduction but also functional impacts of tunnel configuration on things such as life safety are discussed in this paper.
KEK, Ibaraki
CERN, Geneva
Politecnico/Milano, Milano
To investigate the breakdown characteristic related to the differences in purity and hardness, four types of oxygen-free copper (OFC) materials, usual class 1 OFC with/without diamond finish, 7-nine large-grain copper and 6-nine hot-isotropic-pressed copper, were tested with the DC spark test system at CERN. Measurements of beta, breakdown fields and breakdown probability are discussed followed by the surface inspection mostly with SEM on the tested materials.
KEK, Ibaraki
Fermilab, Batavia
The X-band pulse compression system has been developed for the high gradient experiment of the accelerating structure in the new X-band test facility (Nextef). The one channel circular polarized traveling wave delay line was selected to obtain the higher RF compression efficiency under limited delay line length and the easier operation than the cavity chain type. This delay line of the circular waveguide is also frequently used for the C-band feed line from the modulator floor to the accelerator test floor. Thus the delay line is tilted and has the limited length of around 20m. It is designed to obtain the three times compressed power which has the pulse duration of 150 ns. Further we also proceed the upgrade plan using the TE21 mode to double the pulse duration. In this paper, the design overview of this pulse compression system and the RF components including the mode launcher and the TE11-TE21 reflector will be presented.