High Precision Transverse Emittance Measurement for Novel Plasma Accelerators at the REGAE Linac

The small 5 MeV linear accelerator REGAE at DESY produces ultra short and low charge electron bunches, on the one hand to resolve the excitation transitions of atoms temporally by pump-probe electron diffraction experiments and on the other hand to investigate principal mechanisms of laser plasma acceleration. In this context the external injection of the REGAE electron bunch as a probe of the generated plasma wakefield is planned. For both cases a high quality electron beam is required which can be identified with a small beam emittance. A standard magnet scan using a solenoid and a scintillator based detector system has been used for the emittance measurement which is in case of a low charge bunch most sensitive to the beam size determination (RMS or 2nd central moment of a distribution). The detector system could be characterized and is adapted for transverse beam dynamics studies in terms of sensitivity and spatial resolution. E.g. the detector efficiency could be determined and a theoretical estimation be cross-checked.To achieve precise and reliable results an image post-processing routine has been developed in order to deal with the noise contribution to the rms determination. It could be made use of the nature of the noise to define profound noise cuts. As a result highly precise emittance measurements could be performed and the robust post-processing routine could be established.The second topic of this work considers the assembling and characterization of permanent magnetic solenoids (PMS) for the external injection experiments in context of the upcoming laser plasma acceleration experiments. The demands on the electron beam in order to inject it in a matched manner asked for strong focusing magnets located close to the injection point into the plasma. A sorting algorithm for the piecewise composite PMS has been developed to maintain the field quality. In this context a simple field model and a field quality factor could be described and used for the sorting algorithm. The subsequent magnetic field measurement emphasizes the potential of the sorting algorithm and simultaneously confirms the simple field model. The whole procedure can be easily adapted to other types of permanent magnetic magnets