SLAC, Menlo Park, California
Submitted for the Sector 0-20 Core Team. The SLAC 3km linear electron accelerator has been cut at the two-thirds point to provide beams to two independent programs. The last third provides the electron beam for the Linac Coherent Light Source (LCLS), leaving the first two-thirds available for FACET, the proposed new experimental facility for accelerator science and test beams. In this paper, we describe this separation and several projects to prepare the linac for the FACET experimental program.
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
In order to improve the positron beam intensity needed for super KEKB project, it was decided to replace the present S-band structures in the positron capture section by a new L-band (1298MHz) accelerator system. A 2m long TW structure of 12MV/m gradient is now under idesign process while a 40MW klystron will be delivered in summer. After the klystron testing, a single L-band accelerator unit will be constructed for the structure study. The study is scheduled in next spring to operate the structure under solenoidal magnetic focussing field.
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
The KEK injector linac sequentially provides beams to four storage rings: a KEKB low-energy ring (LER) (3.5 GeV/positron), a KEKB high-energy ring (HER) (8 GeV/electron), a Photon Factory ring (PF ring; 2.5 GeV/electron), and an Advanced Ring for Pulse X-rays (PF-AR; 3 GeV/electron). So far, beam injection to the PF ring and PF-AR had been carried out twice a day, whereas the KEKB rings had been operated in the continuous injection mode (CIM) for keeping stored currents almost constant. The KEK linac upgrade project has started since 2004 so that the PF top-up and KEKB CIM can be operated at the same time. The goal is to inject the beams of different energy into the three independent rings in every 20 ms, where the common DC magnet settings are utilized for beams having different energy and charge, whereas different optimized rf phases are applied to each beam acceleration by using a fast low-level rf control up to 50 Hz. With this noble operation scheme, a simultaneous top-up operation for different three rings was achieved for the first time over the world, and has been stably in operation since last April. We report the operation scheme and status in detail.
