Progress on RPC Tests at the University of Chicago

1
Progress on RPC Tests at the University of Chicago

• Outline
• Prototype chamber
• Gas mixer
• Pulses and spectra
• Future plans

2
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 R134aArIsobutane 62308
• future HARP R134aIsobutaneSF6 9055
• All tests use CR telescope and trigger

3
(No Transcript)
4
Gas Mixer
5
Good Pulses

• It appears we have been seeing streamers, not
  avalanches (thresholds?)

6
Lots of double-pulses
7
and much spontaneous pulsing
8
Trying to understand spectrum
9
A Better CR telescope

• Ed Blucher Aren Jensen Abby Kaboth
• Scintillator DC for fine positioning
• Look for hotspots, etc

10
Good Position Info Now
11
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