Performance of glass RPC operated in streamer mode with four-fold gas mixtures containing SF6

✍ Scribed by C. Gustavino; A. Candela; M. De Deo; M. D'Incecco; R. Moro

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 366 KB
• Volume: 517
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2003.09.059

✦ Synopsis

We have studied the performance of a glass Resistive Plate Chambers (RPC), operated in streamer mode, with several gas mixtures composed by argon, C 2 H 2 F 4 ; iso-C 4 H 10 and SF 6 : A small percentage of SF 6 strongly reduces the streamer size, increasing the RPC rate capability. The UV photons involved in the streamer process are also decreased, allowing their absorbtion with an isobutane percentage well below the flammability limit. Besides the streamer reduction, the SF 6 increases the size of the avalanche signal preceeding the streamer. By exploiting the relatively large amplitude of the prompt precursor, a time resolution of about 1 ns (r.m.s.) has been obtained over the whole full efficiency region. Our measurements suggest that the SF 6 cannot replace the C 2 H 2 F 4 ; which must have a level of about 50%; in order to minimize the amount of afterpulses.