CERN Accelerating science

Left: Schematic view, in the R-z plane, of one quadrant of the CMS detector. The position of the RPC chambers is shown (not to scale). Right: Schematic layout of a double-gap barrel chamber composed by two sub-units, called rolls. The readout strip plane is also shown.

Left: Schematic view, in the R-z plane, of one quadrant of the CMS detector. The position of the RPC chambers is shown (not to scale). Right: Schematic layout of a double-gap barrel chamber composed by two sub-units, called rolls. The readout strip plane is also shown.

Schematic drawing of the extrapolation method. A DT or CSC track segment is linearly extrapolated to the RPC strip plane. RPC hits are sought in the acceptance region around the extrapolated impact point.

Efficiency measurement (in \%), as a function of the effective High Voltage $\mathrm{HV_{eff}}$ (in kV) for a typical chamber. The ``knee'' and the optimal working point, shown in the picture, are defined in the text.

HV$_{50\%}$ (in kV) distribution for the barrel (left curves, red and blue) and the endcap (right curves, green and black) rolls. The red and green curves show 2012 data. HV$_{50\%}$ is the inflection point of the sigmoid, for which 50\% of the asymptotic efficiency is obtained.

Left: Barrel efficiency (in \%) as a function of the run number, {\it i.e.} as a function of time, for runs taken between April 2011 and October 2011. The two regions, before and after the automatic $\mathrm{HV_{eff}(P,T)}$ correction, are shown in the plot. Right: Endcap cluster size (in number of strips), as a function of the run number, for the same run range between April and October 2011.

Left: Barrel efficiency (in \%) as a function of the run number, {\it i.e.} as a function of time, for runs taken between April 2011 and October 2011. The two regions, before and after the automatic $\mathrm{HV_{eff}(P,T)}$ correction, are shown in the plot. Right: Endcap cluster size (in number of strips), as a function of the run number, for the same run range between April and October 2011.

Average cluster size for the barrel (left) and for the endcap (right), in number of strips, as a function of the atmospheric pressure P (in mbar), for runs before (left, blue curve) or after (right, red curve) the automatic $\mathrm{HV_{eff}(P,T)}$ correction. Preliminary results with 2011 data are shown.

Average cluster size for the barrel (left) and for the endcap (right), in number of strips, as a function of the atmospheric pressure P (in mbar), for runs before (left, blue curve) or after (right, red curve) the automatic $\mathrm{HV_{eff}(P,T)}$ correction. Preliminary results with 2011 data are shown.