| Paper | Title | Page |
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| WEPCH115 | Numerical Simulation and Optimization of a 3-GHz Chopper/Prebuncher System for the S-DALINAC | 2185 |
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| A new source of polarized electrons with an energy of 100 keV is presently being developed at the superconducting Darmstadt electron linear accelerator S-DALINAC for future nuclear- and radiation-physics experiments. The pulsed electron beam emitted by the photocathode will be cut to 50 ps by a chopper operated at 3 GHz, and further bunch compression down to 5 ps will be achieved by a two-stage prebuncher section. The chopper-prebuncher system is based on similar devices used at the Mainz Mikrotron (MAMI) where the accelerator frequency is slightly smaller (2.4 GHz). For the chopper, a cylindrical resonator operating at TM110 mode is selected to deflect the electron beam onto an ellipse, i.e., both horizontally and vertically. This is simply achieved by particular slits on both ends of the resonator. The prebunching system consists of two cavities. For increasing the longitudinal capture efficiency, the first cavity will be operated at the fundamental accelerator frequency of the S-DALINAC of 3 GHz, and the second cavity at 6 GHz. The cavities are designed to work at the TM010 mode and TM020 mode for the fundamental and first harmonic, respectively. | ||
| WEPCH116 | Recent Simulation Results of the Polarized Electron Injector (SPIN) of the S-DALINAC | 2188 |
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| Recent design and development for a polarized electron source (SPIN) for the recirculating superconducting electron linear accelerator S-DALINAC will be presented. The polarized electron beam will be produced by photoemission from an InAlGaAs/GaAs superlattice cathode and will be accelerated to 100 kV electrostatically. The results of the beam dynamics simulation will be shown in detail. The start phase space of the electron bunch behind the gun has been approximated. The transverse focusing system consists of very short quadrupoles. Further main components of the new injector are a Wien filter, a Mott polarimeter, a chopper-prebuncher system (based on devices used at the Mainz Mikrotron MAMI), and diverse beam diagnostic tools. For the approximation of the start phase space CST MAFIA is used, and for the beam dynamic simulation VCode is used. | ||
| THPCH161 | Status of the Polarized Electron Gun at the S-DALINAC | 3173 |
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Aiming at an extension of the experimenting capabilities for nuclear structure physics at low momentum transfer at the superconducting Darmstadt electron linear accelerator S-DALINAC, a polarized electron gun is being constructed. The new injector will be able to supply the S-DALINAC with 100 keV polarized electrons and should complement the present, unpolarized thermionic source. The design requirements are a degree of polarization of at least 80%, a mean current intensity of 0.06 mA and a 3 GHz cw structure. The basic design of the gun was adapted from the source of polarized electrons at MAMI, Mainz*, and optimized in various simulations. The active material is a strained layer GaAs crystal which is exposed to an 830 nm pulsed laser beam. We report on the status of the polarized source, the preparation setup and a test beam line.
*K. Aulenbacher et al., Nucl. Instrum. Meth. A 391, 498 (1997). |