New Installations and Beam Measurements at MAMI

During the past 3 years the cw racetrack microtron cascade MAMI [1] has been significantly improved, thus extending the scope of experiments in nuclear and radiation physics. The 100keV injection was successfully reconstructed for the installation of a second source of polarised electrons and for increased capture efficiency ([2],[3],[6]). At the high energy end of the accelerator a new transport line was installed to guide the beam to two of the old experimental areas for experiments with coherent x-rays (collaboration X1). The beam diagnostics were further extended by: 1) synchrotron radiation monitors in the last two microtrons (RTM2&3), enabling emittance measurements at higher cw beam currents, 2) improved rf position and 3) a larger number rf phase monitors. Two of the latter, working at 9.8GHz, are used for a second high resolution beam energy measurement. On the occasion of transverse beam optical measurements in RTM3 beam current-depending nonlinearities were detected. There were most probably caused by iontrapping in the electrical potential of the beams on the linac axis.