Tests of multigap RPCs for high-η triggers in CMS

Abstract

View the article online for updates and enhancements. Related content Rate-capability study of a four-gap phenolic RPC with a 137 Cs source K S Lee-Study of an avalanche-moderesistive plate chamber J Ying, Y L Ye, Y Ban et al.

Rate-capability study of a four-gap phenolic RPC with a137Cs source

“…Water vapour of approximately 0.3% (mass ratio) was added to the gas mixture, in order to maintain the constant bulk resistivity of the HPL used in the prototype RPC. The applied high-voltage (HV app ) values were converted to effective values (HV eff ), under the standard conditions, of P = 1013 hPa, and T = 293 K as explained in [6].…”

“…Furthermore, the detector current drawn in unit area of the present CMS double-gap RPCs is about 300 µA m −2 at a particle rate of 1 kHz cm −2 , which far exceeds the practical limit that guarantees longevity in the detector operation [4,5]. As discussed in the previous research [6], magnitude reduction of the avalanche pulses will be the best choice for the new high-η trigger RPCs in the CMS experiment. In order to prove the detector performance of the four-gap RPC using a 32channel front-end-electronics (FEE) board that has been developed for the operation of the current CMS RPCs, a prototype four-gap RPC was manufactured with phenolic high-pressure-laminated (HPL), and tested with cosmic muons and gamma rays emitted from a 137 Cs gamma-ray source.…”

“…The active area of producing the gamma hits was measured as 500 cm 2 . Thus, the detector current drawn per unit detection area and per unit gamma-hit rate of kHz cm −2 , measured in the mid of the ε µ plateau of the four-gap RPC (12.17 kV), is expected to be about 80 µA m −2 (kHz cm −2 ) −1 ; this is about one third of that drawn in a typical double-gap RPC [6]. Figure 7 shows the distributions of mean strip-cluster sizes for muons < C s,µ > and for gamma hits < C s,γ > measured at 11.76 (left), and 12.17 kV (right).…”

“…2 Construction of the prototype four-gap RPC A four-gap RPC is composed of two bi-gaps and a strip panel, as described in the previous report [6]. For the present research, a new panel-shape four-gap RPC with an active area of 45 × 45 cm 2 was manufactured with 2-mm-thick phenolic HPL.…”

Upgrade of the CMS Muon System

“…Also multi-gap RPCs built using standard CMS bakelite are under study, and the relative results are very encouraging [14], and the possibility to use double gap CMS RPCs with a more sophisticated electronics and better shielding is being investigated as well.…”