Timing of the CMS tracker: Study of module properties

One of the crucial aspects of the commissioning of the CMS silicon tracker will be the absolute timing of each module, to accommodate both delays introduced by the hardware configuration and effects due to the time-of-flight of particles. The objective is to be optimally synchronized with the bunch-crossing to maximize the efficiency while minimizing the number of remnant hits from the adjacent bunch-crossings. In the present note, a procedure to reach that goal is deduced from the analysis of results obtained on a simple test setup. Emphasis is put on the parametrization of the pulse shape and on the effect of capacitive coupling between adjacent strips.It is shown that the pulse from the leading strip must be used as a reference during the timing procedure, in order to have asymmetric efficiency over consecutive bunch crossings and to avoid fake clusters.