Progress on RPC Tests at the University of Chicago Outline: Prototype chamber Gas mixer Pulses and spectra Future plans 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell The Default Design ANL was kind enough to send us a chamber, which we have reworked several times Our aim is to test gas mixtures and look for surface damage, so we have a single readout pad The resistive layer is sprayed graphite Initial gas: R134a:Ar:Isobutane 62:30:8 future: HARP: R134a:Isobutane:SF6 90:5:5 All tests use CR telescope and trigger 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell Gas Mixer 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell Good Pulses It appears we have been seeing streamers, not avalanches (thresholds?) 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell Lots of double-pulses 14 July 2003 Mark Oreglia, LCW Cornell

… and much spontaneous pulsing 14 July 2003 Mark Oreglia, LCW Cornell

Trying to understand spectrum 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell A Better CR telescope Ed Blucher + Aren Jensen + Abby Kaboth Scintillator + DC for fine positioning Look for hotspots, etc 14 July 2003 Mark Oreglia, LCW Cornell

Mark Oreglia, LCW Cornell Good Position Info Now 14 July 2003 Mark Oreglia, LCW Cornell

What We are Investigating Origin of spontaneous discharges Effects of surface quality Surface damage Gas mixtures and their relation to the problems mentioned above Gas pressure and chamber ballooning A real problem… Stable operation disrupted for very slight deformation of chamber 14 July 2003 Mark Oreglia, LCW Cornell