ORNL/SNS, Oak Ridge, Tennessee
* on behalf of the SNS Project
INFN/LNL, Legnaro, Padova
ELETTRA, Basovizza, Trieste
POSTECH, Pohang
DESY, Hamburg
KEK, Ibaraki
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| WE201 | Results from the Initial Operations of the SNS Front End and Drift Tube Linac | 533 |
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The Spallation Neutron Source accelerator systems will deliver a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector (the Front-End), capable of producing one millisecond long pulses with 38 mA of peak current at a repetition rate of 60 Hz, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. A 2.5 MeV beam from the injector is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in a Superconducting Linac. The staged beam commissioning of the accelerator is proceeding in parallel with component installation. The Front End and Drift Tube Linac tanks 1-3 have been commissioned at ORNL. The primary design goals of peak current, transverse emittance and beam energy have been achieved. Beam with 38 mA peak current, 1 msec beam pulse length, and 1 mA average beam current has been accelerated through the DTL tank 1. Results and status of the beam commissioning program will be presented.
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| WE202 | Recent Results in the Field of High Intensity CW Linac Development for RIB Production | 538 |
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| High Intensity CW Linacs have been proposed as driver accelerators for RIB production in various projects, since thy can drive in steady conditions a MW power range target for the production of spallation neutrons that induce fission in a natural uranium target. Particularly important for this application, with a relatively low beam current, is the necessity to develop a superconducting intermediate energy part with good power conversion efficiency. The second specific requirement of RIB facility drivers, that is also fulfilled by a superconducting intermediate energy linac, is the necessity to keep some flexibility in the species that can be accelerated (deuterons or light ions). In EURISOL RTD project a 1 GeV 5 mA proton linac, has been proposed for this application. In SPES project, recently approved for its initial phase at LNL, a lower energy proton beam will be used on a solid target. The results of the specific R&D programs on in the field of CW RFQ and superconducting low energy linacs will be illustrated. In particular for LNL the status of the RFQ construction and the superconducting cavities prototype tests will be given. | ||
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| WE203 | Challenges of Linac Driven Light Sources | 543 |
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| The use of linacs allows novel light sources to be conceived by not being limited by equilibrium dynamics or IBS effects. These new sources can be single pass or recirculated (with or without energy recovery) or linac augmented storage rings. They allow tuneable polarised radiation of unprecedented brilliance, short pulse lengths that may reach the atto-second scale and full coherence. Both SC and NC machines are being proposed, designed and constructed. Photon output characteristics range from incoherent synchrotron radiation to SASE to seeded HGHG. The proposed beams can be low to high average current and pulse time structures range from CW to highly variable with mutual exclusion amongst different forms of operation. The multiple challenges of these machines reside not only in the requirement of beams of extremely high quality (energy, emittance, energy-spread and temporal stability) for the brightest, shortest wavelength sources but also in the demanding technologies and control of beam-machine interactions for the high current energy recovery ones. The paper gives an overview of these broad challenges and of the directions taken to reach the objectives of a user facility. | ||
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| WE204 | PAL Linac Upgrade for a 1-3 Å XFEL | 544 |
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| With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-ray beams to 0.1 nm. The technical parameters related to these goals are examined, and preliminary design details are reviewed for the PAL linac upgrade idea for a 1-3 Å PAL XFEL. | ||
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Transparencies | |
| WE205 | KEKB Injector Linac and Upgrade for SuperKEKB | 549 |
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| KEKB Injector linac has provided the 8 GeV electrons and 3.5 GeV positrons to the KEKB asymmetric collider rings designed for the B-physics study. The KEKB has recorded the highest luminosity records to which the linac contributes with an advanced operational stability. The dualbunch injection and continuous injection schemes have been adopted. The operational status of the KEKB injector linac is summarized here. The Super KEKB project aiming for the ten-times higher luminosity is under consideration as the upgrade of KEKB. In this upgrade, the injector linac has to increase the positron acceleration energy from 3.5 GeV to 8 GeV. In order to double the acceleration field (from 20 to 40 MV/m), the C-band rf system has been tested. The newly developed components, such as an acceleration structure and an rf window, are summarized. A C-band acceleration structure is installed in KEKB linac after the rf conditioning of more than 40 MW. The energy gain of more than 40 MV/m is confirmed by the beam analysis. The C-band acceleration unit has been operated continuously for the stability test. The recent operational status of the c-band acceleration unit will be also reported. | ||
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Transparencies |