A measurement of the Lorentz angle in silicon strip sensors at cryogenic temperature

A geometric model of charge collection has been developed to measure the Lorentz angle in silicon sensors. The model relates the track inclination to the average cluster width. A Lorentz angle of 19.6 plus or minus 0.27-0.5+1.0 degree was measured by fitting the model to cosmic ray data collected with the double-sided silicon strip sensors of the ATHENA antihydrogen detector. This measurement corresponds to holes drifting in sensors operated at 130 K, in a 3 T magnetic field and with an average internal electric field of 1.3 kV /cm. Comparisons of charge sharing between strips and track residuals for data taken with and without magnetic field are also presented and support this measurement.