The polarimetry chain for the P2 experiment

We plan to equip the P2 experiment at Mainz with two different types of polarimeters, a so-called double scattering Mott polarimeter and a Møller polarimeter with trapped polarized hydrogen atoms (Hydro-Møller polarimeter). We believe that both polarimeters have the potential to achieve an accuracy in the determination of the effective analyzing power of less than 0.5%

First attempt of the measurement of the beam polarization at an accelerator with the optical electron polarimeter POLO

The conventional methods for measuring the polarization of electron beams are either time consuming, invasive or accurate only to a few percent. We developed a method to measure electron beam polarization by observing the light emitted by argon atoms following their excitation by the impact of polarized electrons. The degree of circular polarization of the emitted fluorescence is directly related to the electron polarization. We tested the polarimeter on a test GaAs source available at the MAMI electron accelerator in Mainz, Germany. The polarimeter determines the polarization of a 50 keV electron beam decelerated to a few eV and interacting with an effusive argon gas jet. The resulting decay of the excited states produces the emission of a circularly polarized radiation line at 811.5 nm which is observed and analyzed

Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering off 28^{28}Si and 90^{90}Zr

We report on a new measurement of the beam-normal single spin asymmetry $A_{\mathrm{n}}$ in the elastic scattering of 570 MeV transversely polarized electrons off $^{28}$Si and $^{90}$Zr at $Q^{2}=0.04\, \mathrm{GeV}^2/c^2$. The studied kinematics allow for a comprehensive comparison with former results on $^{12}$C. No significant mass dependence of the beam-normal single spin asymmetry is observed in the mass regime from $^{12}$C to $^{90}$Zr.Comment: Submitted for publication to Physics Letters

Recent Status of the MAMI C Accelerator and First Experiences with the Energy Upgrade towards 1.6 GEV

The University of Mainz institute for nuclear physics is operating the microtron cascade MAMI Mainzer Mikrotron since the late 1970ies. The microtron delivers a cw electron beam to users of the hadron physics community. The recent, fourth stage MAMI C having a design energy of 1.5 GeV is operated since 2006 [1]. This article deals with the recent developments and operational experiences of MAMI C, as well as with the energy upgrades to 1.56 GeV [2] and as final step towards 1.6 GeV. The final increase of beam energy was due to user demands, since it is expected to raise the event rate of the amp; 951; production by an order of magnitud