MAMI
MAMI’s excellent beam quality and reliability in the energy range up to 1.6 GeV has been the basis for trailblazing precision experiments. Two major experiments, the A1 three-spectrometer setup and the A2 Crystal Ball – TAPS, enable for one part of the experimental program of this CRC:
The most prominent facility is the A1 three-spectrometer setup which is optimized for precision coincidence measurements of charged particles in exclusive electron scattering experiments. Its outstanding momentum resolution of $10^{−4}$ allows the detection of charged particles with high resolution and purity. As an example, this set-up has pioneered the measurement of virtual Compton scattering which has initiated the deeply virtual Compton scattering physics program at higher energies, in particular at JLab. More recently, the superior performance has once again been used in an innovative way in the search for dark photons and in an in-depth program on beam-normal single spin asymmetries.
The second experimental setup at MAMI is the Crystal Ball detector at the tagged photon beamline, which is operated in combination with the TAPS calorimeter, thus offering full coverage of the solid angle and a high efficiency for electromagnetic particles. A major new contribution to the experimental equipment of the A2 Collaboration is the frozen-spin target for polarized protons and deuterons. Both longitudinal and transverse polarization can be provided, and as such the polarized target. The average degrees of polarization (approximately 70%) and the relaxation times (approximately 3000 hours for butanol) are among the highest in the world.
The X1 beamline is located behind the third stage of the microtrons and is operated with maximum beam energies of 855 MeV. This beamline is used for experiments to investigate brilliant novel radiation sources and to explore their potential for applications, but also serves as a perfect environment for detector tests.