M. BRUNKEN, H. GENZ, M. GOPYCH, H.-D. GRAEF, S. KHODYACHYKH, S. KOSTIAL, U. LAIER, A. LENHARDT, H. LOOS, J. MUEHL, M. PLATZ, A. RICHTER, S. RICHTER, B. SCHWEIZER, A. STASCHECK, O. TITZE, S. WATZLAWIK (TU Darmstadt), S. DOEBERT (CERN)
The S-DALINAC is a 130 MeV superconducting recirculating electron accelerator serving several nuclear and radiation physics experiments as well as driving an infrared free-electron laser. A system of normalconducting HF resonators for noninvasive beam position and current measurement was established. The achieved position sensitivity of the system is 15 pW/(mm uA)^2, the current sensitivity is 15 nW/(uA)^2. For the measurement of gamma-radiation inside the accelerator cave a system of compton diodes has been developed and tested. The very robust devices deliver typically several pA of current for a dose rate of 10 mSv/hr. Detailed investigations of the transverse phasespace were carried out with a tomographical reconstruction method of optical transition radiation spots. The method can be applied also to non-gaussian phasespace distributions. The results are in good accordance with numerical simulations. To improve the quality factor of the superconducting 3 GHz cavities, an external 2K testcryostat was commissioned. The influence of electro-chemical polishing and magnetic shielding is currently under investigation. A digital RF-feedback-system for the accelerator cavities is under development in order to achieve a better energy resolution of the S-DALINAC. The digital signal processing techniques including lookup tables and feedforward corrections will besides other advantages over the present system allow for a better adaption to imperfections of system components.
* Supported by the BMBF under contract no. 06 DA 820, the DFG under contract no. Ri 242/12-1 and -2 and the DFG Graduiertenkolleg 'Physik und Technik von Beschleunigern'
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