RPC R&D Approved Results for Conferences

Plots approved for the TDR 2017

iRPC results

Figure	Description
	Average charge per avalanche measured on 1.20 mm (full circles), 1.40 mm (open circles), 1.60 mm (triangles), and 2.0 mm (squares) double-gap RPCs, as a function of the effec- tive electric field strength. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Efficiency and average cluster size ⟨Cs⟩ , measured for the 1.4-mm double-gap RPC with a fixed threshold value of 300 μV and with three different gamma fluxes. The intensity of the gamma flux impinging on the RPC was defined by adjusting the distance of the detector from the gamma source (triangles and squares, measured at 38 and 28 cm, respectively) and by using a lead absorber (full circles measured with an absorption factor of about 2.5, at a distance of 38 cm). The Working Point (WP) for the 1.4-mm double-gap RPC is defined as the voltage at which the efficiency reaches 95%, increased by 110 V. The rates, Rstr (rate of strips) and Rclus (rate of clusters), measured at the working point with the largest gamma flux yields (at a distance of 28 cm) were found to be 4.14 and 1.85 kHz/cm2, respectively. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Efficiency εμ and average cluster size ⟨Cs⟩ (left) and εμ and P(Cs >6) (right), mea- sured for the 1.4-mm double-gap RPC with a fixed threshold value of 300 μV and with three different gamma fluxes. The intensity of the gamma flux impinging on the RPC was defined by adjusting the distance of the detector from the gamma source (triangles and squares, measured at 38 and 28 cm, respectively) and by using a lead absorber (full circles measured with an absorption factor of about 2.5, at a distance of 38 cm). The Working Point (WP) for the 1.4-mm double-gap RPC is defined as the voltage at which the efficiency reaches 95%, increased by 110 V. The rates, Rstr (rate of strips) and Rclus (rate of clusters), measured at the working point with the largest gamma flux yields (at a distance of 28 cm) were found to be 4.14 and 1.85 kHz/cm2, respectively. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Efficiency at the working voltage, as a function of the cluster rate for the 1.4 mm double-gap RPC. The data were measured at the fixed threshold of 300 μV. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Average cluster size at the working voltage, as a function of the cluster rate for the 1.4 mm double-gap RPC. The data were measured at the fixed threshold of 300 μV. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Efficiency and average cluster size of a 1.4 mm double-gap RPC large size chamber as a function of the effective voltage, tested without gamma background. The data were measured at the fixed threshold of 300 muV and fitted with a sigmoidal function. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Efficiency and average cluster size of a 1.4 mm double-gap RPC large size chamber as a function of the effective voltage, tested under a gamma background rate of 1.91 kHz/cm2. The data were measured at the fixed threshold of 300 muV and fitted with a sigmoidal function. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Efficiency and Cluster size vs. effective voltage for the CMS gas mixture and an ecological gas mixture. Contact : cms-rpc-upgrade-coordinators at cern.ch

Front-end electronics results

Figure	Description
	Time difference of the time arrival between the first strip end and that of the trigger T1-T0 . Contact : cms-rpc-upgrade-coordinators at cern.ch
	Measured time difference of the signal arrival time of each of the two fired strip ends T2-T1 as a function of the Y position of the scintillator-PM system center with respect to the RPC. Arbitrary origin of the Y axis is used. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Time resolution of the arrival time difference, at the two edges of the strips, when a signal of 10 pC is injected on one of the ASU’s strips. Contact : cms-rpc-upgrade-coordinators at cern.ch

Longevity studies for the CMS RPC system

Figure	Description
	Current ratio between irradiated and non-irradiated reference chambers as a function of the integrated charge. Red circles correspond to RE2/2 chambers, blue squares to RE4/2. The difference in the ratio between RE2/2 and RE4/2 chambers is due to the different relative position of the chambers with respect to the reference chambers. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Rate ratio between irradiated and reference chambers as a function of the integrated charge. Red circles correspond to RE2/2 chambers, blue squares to RE4/2. The difference in the ratio between RE2/2 and RE4/2 chambers is due to the different relative position of the chambers with respect to the reference chambers. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Hit Efficiency (solid line) and streamer probability (dashed line) as a function of the effective working voltage for gas mixtures with different combinations based on CF3I and CO2. The results are compared with the present RPC CMS gas mixture. The streamer probability is defined as the fraction of events with an induced charge above 20 pC. Contact : cms-rpc-upgrade-coordinators at cern.ch
	Hit Efficiency (solid line) and streamer probability (dashed line) as a function of the effective working voltage for gas mixtures with different combinations of HFO-1234ze gas and CO2 (top). The results are compared with the present RPC CMS gas mixture. The streamer probability is defined as the fraction of events with an induced charge above 20 pC. Contact : cms-rpc-upgrade-coordinators at cern.ch

Plots approved in 2017

Aging studies for the CMS RPC system

Figure

Description

The integrated charge collected up to now for the consolidation studies at GIF++ is shown as function of time. The consolidation studies were started in July 2016 including only the RE2 type chamber whereas the RE4 type chamber was only included in October 2016. Different slopes account for different attenuation factors during data taking. The flat periods to test beam periods or winter break. Contact : cms-rpc-upgrade-coordinators at cern.ch

Stability of the current of both RE2 and RE4 type chambers as function of their integrated charge. The ratio is defined as the current of the irradiated over the reference chamber. The measurements were performed under approximately the same conditions concerning background rate and working point. Globally no trend is observed and the current can be considered as stable. Small variations are accounted for different chamber conditions such as gas flow differences and overpressure. The ratio difference between both chamber types is due to the position of the chambers w.r.t. the source. Contact : cms-rpc-upgrade-coordinators at cern.ch

Efficiency versus background rate for both the irradiated and reference chamber of the RE2 type is shown. The data is collected during three test beam periods at GIF++ from October 2015 to May 2017. Error bars account for the uncertainty of the tracking algorithms used to compute the efficiency and the amount of voltage points used. No efficiency drop is observed for background rates up to 600 Hz/cm². Comparing the irradiated and the reference chamber, no degradation of the efficiency is observed up to an integrated charge of 153 mC/cm². Contact : cms-rpc-upgrade-coordinators at cern.ch

Plots approved in 2016

Plots approved for RPC2016 (February 2016)

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-- IsaPedraza - 2016-07-18