%\subsubsection{Beam rastering}
To avoid radiation damage to the target the beam will be rastered over the target surface in a spiral pattern. The beam position  is measured indirectly by recording the simultaneous currents of the raster magnet. These values can be used off-line to correct for effects of the raster on the vertex z-position. 
The raster magnets may be also used to give a small angle ($\sim 0.1^o$) to the incident electron beam, so that 
beam at target center will be collinear with the z-axis to confine bremsstrahlung photons into the beam pipe. 

