| Paper | Title | Page |
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| MOP008 | Design and Performance of Optics for Multi-Energy Injector Linac | 46 |
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| Injector linac provides injection beams for four storage rings, KEKB high energy electron ring (HER), KEKB low energy positron ring (LER), PF-AR electron ring, and PF electron ring. The injection beams for these rings have different energies and intensities. Recently, a requirement of simultaneous injection among these rings arises to make a top-up injection possible. Magnetic fields of DC magnets to confine the beam to the accelerating structures can not be changed between pulse to pulse, although the beam energy can be controlled by fast rf phase shifters of klystrons. This implies that common magnetic fields of bending magnets and quadrupole magnets should be utilized to deliver beams having different characteristics. Therefore, we have designed multi-energy optics for KEKB high energy electron ring (8 GeV, 1 nC/pulse) and PF electron ring (2.5 GeV, 0.1 nC/pulse) and present a performance of the multi-energy injector linac. | ||
| THP087 | Status of C-band Accelerating Section Development at the KEKB Injector Linac | 788 |
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| This paper reports on C-band accelerating section development for future energy upgrade of the KEKB injector linac. Target field gradient is 42 MV/m, that is twice of the present S-band sections in the linac. Until now, we have developed four 1m-long sections based on a half-scale design of the S-band section with improvements in coupler cavity shape and in fabrication method. And the fifth accelerating section is in fabrication now. The four sections have already installed in the beam line of the linac. Together with a unit of C-band rf source (50 MW klystron, pulse modulator, rf-pulse compressor) installed in the linac, we will perform an operation test of a model C-band accelerator module that has almost same configuration as a design module in the upgrade. Results of the long-term operation test and beam acceleration study will be described. And present status of development of the fifth accelerating section will also be given. | ||
| THP091 | Experimental Study of Positron Production from Monocrystalline Targets at the KEKB Injector Linac | 797 |
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Intense positron sources are widely investigated for the next-generation of linear colliders and B-factories. A new method utilizing an axially-oriented crystal as a positron-production target is one of the bright schemes since it provides a powerful photon source through channeling and coherent bremsstrahlung processes when high-energy electrons penetrate the target. A series of positron-production experiments with tungsten crystal alone and diamond target combined with an amorphous tungsten plate have been carried out at the KEKB injector linac. The tungsten crystals with different thicknesses (2.2, 5.3, 8.9, 12.0 and 14.2 mm) and the diamonds with different thicknesses (4.57 and 7.25 mm) were tested on a goniometer by using 4 and 8-GeV electron beams, respectively. The positron-production yields were measured with a magnetic spectrometer at the positron momentum of 10 and 20 MeV/c. In this report the experimental results are summarized on the enhancements of the positron yield from these crystal targets compared to amorphous targets of the same thickness.
*Email address: tsuyoshi.suwada@kek.jp |