| Paper | Title | Page |
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| MO6RFP066 | Operational Performance of Positron Production from Tungsten Single-Crystal Target at the KEKB Injector Linac | 518 |
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The first operation of the positron production with a tungsten single-crystal target has been performed at the positron source of the KEKB injector linac for the KEK B-factory (KEKB) from September 2006 to June 2007 (~10 months). Previously we carried out the systematic studies on the positron-production efficiencies with tungsten crystals having various thickness using 4- and 8-GeV electron beams at the test beam line during the term of 2000-2005. Finally, we optimized the thickness of the tungsten crystal at 4 GeV and developed both the target fabrication technique and the crystal-axis alignment technique in 2006. After the systematic studies, we installed a tungsten crystal target at the KEKB positron source without any significant modifications for the positron source. The data on the positron production, especially, the positron-production efficiencies and stabilities in terms of the primary electron and positron beams, were obtained during the nominal KEKB operation in this term. We summarize the long-term operational performance on the positron production with the tungsten crystal target at the KEKB injector linac in this report. |
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| TU5RFP081 | Status of the Energy Recovery Linac Project in Japan | 1278 |
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Future synchrotron light source project using an energy recovery linac (ERL) is under proposal at the High Energy Accelerator Research Organization (KEK) in collaboration with several Japanese institutes such as the JAEA and the ISSP. We are on the way to develop such key technologies as the super-brilliant DC photo-injector and superconducting cavities that are suitable for both CW and high-current operations. We are also promoting the construction of the Compact ERL for demonstrating such key technologies. We report the latest status of our project, including update results from our photo-injector and from both superconducting cavities for the injector and the main linac, as well as the progress in the design and preparations for constructing the Compact ERL. |
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| WE6PFP043 | Recent Progress of KEKB | 2588 |
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Crab cavities were installed at KEKB at the beginning of 2007. The beam operation with the crab cavities is in progress. In this paper, machine performance with crab crossing is described focusing on a specific luminosity and a beam lifetime issue related to the dynamic beam-beam effects. |
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| WE6PFP110 | Pulse-to-Pulse Switching Injection to Three Rings of Different Energies from a Single Electron Linac at KEK | 2769 |
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The e+/e- injector LINAC in KEK usually successively injects into four rings, which are Low Energy Ring (LER) of KEKB (3.5GeV/e+), High Energy Ring (HER) of KEKB (8.0GeV/e-), Photon Factory (PF) (2.5GeV/e-) and Advanced Ring for pulse X-rays (PF-AR) (3.0GeV/e-). While LINAC continuously injects into LER and HER alternatively every about five minutes, keeping both of KEKB rings almost their full operating currents. It takes about one minute to switch beam mode of LINAC. PF and PF-AR are injected a few times in a day. Time for PF or PF-AR including mode-switch had taken about 20 minutes for each other. For PF injection, the switching time was shortened in 2005 and the occupancy time is about 5 minutes. In 2008, we succeeded to make the switching time shorter, 2 seconds for HER/LER, and Pulse-to-pulse alternatively injection for PF/HER using an event system. Especially for KEKB, the short switching time is contributed to provide high currents and to improve luminosity at which beam lives are too short to keep the high currents. In 2009, we have a plan to inject also for LER/HER pulse-to-pulse alternatively. |
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| FR5REP010 | Event-Based Timing and Control System for Fast Beam-Mode Switching at KEK 8-GeV Linac | 4797 |
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The 8-GeV linac at KEK provides electrons and positrons to several accelerator facilities. A 50-Hz beam-mode switching system has been constructed to realize simultaneous top-up injections for Photon Factory and the KEKB high- and low-energy rings, which require different beam characteristics. An event-based timing and control system was built to change the parameters of various accelerator components within 20 ms. The components are spread over a 600-m linac and require changes to a total of 100 timing and control parameters. The system has been operated successfully since the autumn of 2008 and has been improved upon as beam operation experience has been accumulated. It is expected to enhance the quality of the experiments at KEKB and PF. We describe the details of this new and improved control system and present status of the accelerator operation. |