Münster 2017 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 34: Instrumentation VIII and Accelerators

HK 34.5: Talk

Wednesday, March 29, 2017, 18:00–18:15, F 073

Data analysis of the high-accuracy electron beam energy measurement at the Mainz Microtron — •Philipp Herrmann, Patrick Achenbach, Pascal Klag, Sho Nagao, Satoshi N. Nakamura, Josef Pochodzalla, Shoko Tomita, and Yuichi Toyama — Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz

The Mainz Microtron MAMI delivers an electron beam of up to 1.6 GeV. The absolute energy is measured inside the third stage of the accelerator with an accuracy of δ E_beam = 160 keV independent of the beam energy, with an energy spread σ_beam < 13 keV and long-term drifts of less than 1 keV when stabilized. To obtain an absolute energy measurement within δ E_beam ∼ 20 keV uncertainty, a 42^∘-dipole of the beam-line leading to the spectrometer facility is used as a high-accuracy beam spectrometer. A high-precision field mapping device was developed and a dedicated beam detection system of RF cavity position monitors and YAG:Ce screens was implemented. Therefor the goal was to achieve 10 µT, 10 µm uncertainties in the field mapping and an electron beam deflection angle measurement with δ θ/θ < 10⁻⁵.
With this setup we were able to obtain 10000 data points, in x, y and z field direction, for different field values and probe positions. Thus enabling us to use a linear approximation in order to calculate a complete field map along the path of the electrons through the dipole.
Using the the YAG:Ce screens to measure the offset of the RF cavity monitors every 30 min, we archived the high accuracy measurement of the beam position/deflection angle. In this presentation the results and difficulties will be presented, in regard to provide a well known incident particle energy for scattering experiments at MAMI.