Description of Apparatus

These data were obtained in room 4C in the basement of Robeson Hall at VPI in Blacksburg,VA. A 25cm x 25cm glass RPC identified as M6 was used. It was placed in the test stand above the production superlayers. The gas flow was from the exhaust of superlayer 2-16. A two-fold scintillator coincidence was set up using a 30cm x 30cm scintillator and a 12cm x 13cm scintillator placed above the M6 RPC. The -HV was supplied from the long-term test -HV bus using a CAEN power supply. The +HV was supplied by a Kiebler supply and the +current was measured with an inline digital microammeter with a 10 nanoAmp least count. The digital display updated approximately once a second. The current quoted is the average value. It was stable at the 10 nanoAmp level until several hundred volts above the knee of the efficiency curve (sensitivity to minimum ionizing radiation). At the highest voltages measured the current fluctated by as much as 200 nanoamps.

The RPC signal traveled down ~75' of RG58 cable to a linear fanout. From the fanout it went to a LeCroy 2249W ADC with a 290ns gate and to a 30mV discriminator. The discriminator output was 50 ns wide and was sent to a LeCroy 2228A TDC and to a scaler to count the singles rate.

The pulse size quoted is the central value of the single pulse peak. The error bars indicate not the error in this measurement but the full width at half maximum (FWHM) of this peak as an indication of the spread in pulse size. Above the efficiency knee a significant fraction of the events have multiple pulsing which can be seen as secondary peaks in the ADC spectrum and is also reflected in the increased singles rate.

Measured Quantities vs. Voltage

• Efficiency
• Current
• Singles Rate
• Pulse Size
• Time Drift

Measurements at 7.0kV vs. Temperature

• Pulse Size
• Current
• Singles Rate
• Timing

Measurements using the long-term 32 m**2 RPCs

These data are from the 16 long-term 1 x 2 m**2 RPCs. They are all powered from the same negative HV channel but have independent +HV channels. The current shown is that measured on the single -HV cable supplying the bus.

• Current vs. Voltage
• Current vs. Temperature

Measurements at 21 C with various barometric pressures

• Pulse size vs. Barometric Pressure
• Timing vs. Barometric Pressure
• Singles Rate vs. Barometric Pressure
• Efficiency vs. Barometric Pressure