Author/Authors :
Beckmann، نويسنده , , M and Borissov، نويسنده , , A. Brauksiepe، نويسنده , , S and Burkart، نويسنده , , F and Fischer، نويسنده , , H and Franz، نويسنده , , J and Heinsius، نويسنده , , F.H and Kِnigsmann، نويسنده , , K and Lorenzon، نويسنده , , W and Menden، نويسنده , , F.M and Most، نويسنده , , A and Rudnitsky، نويسنده , , S and Schill، نويسنده , , C and Seibert، نويسنده , , J and Simon، نويسنده , , A، نويسنده ,
Abstract :
The design, construction and operation of a Compton back-scattering laser polarimeter at the HERA storage ring at DESY are described. The device measures the longitudinal polarization of the electron beam between the spin rotators at the HERMES experiment with a fractional systematic uncertainty of 1.6%. A measurement of the beam polarization to an absolute statistical precision of 0.01 requires typically 1 min when the device is operated in the multi-photon mode. The polarimeter also measures the polarization of each individual electron bunch to an absolute statistical precision of 0.06 in approximately 5 min. It was found that colliding and non-colliding bunches can have substantially different polarizations. This information is important to the collider experiments H1 and ZEUS for their future longitudinally polarized electron program because those experiments use the colliding bunches only.
