Linear Betatron Coupling in SIS-18

We report on the campaign of April 22, 2009 to measure the strength of the linear transverse betatron coupling |C| in SIS-18 considering only the corresponding difference resonance Qx Qy = 1 using three different approaches: beam loss, emittance exchange and closest tune approach. We measured the natural linear coupling driven by the uncontrolled skew quadrupole components and the linear coupling driven by a single external skew quadrupole installed in the first sector in the SIS-18 lattice.