Acceptance test at Duke

After completion of stringing (still in the stringing station) HV testing of each straw at 1700 volts in air No arcing Current <10 mA About 5-10% wires fail Replace them. Tension measurement. Acceptance criteria 128 Hz < Tension < 170 Hz Tfront – Tback < 3 Hz About ~1% wires fail the test Replace them Seal the tension plate and purging volume Straw volume <1 mb/bar/min Purging volume < 10 mb/bar/min

Front/back tension

Leak Rate –straw volume

Signal Test Use X-ray scanner Ar-CO2(70-30) but no CO2 in the purging volume Current is recorded at 1600 Volts. No attempt to reduce the current below ~100 nA but the current draw is typically less than a few hundred nA after fixing noisy channels. Wires with HV problem are removed and re-strung if necessary. Usually there are one or two wires per module with the problem. No problem for a few days ADC spectrum is recorded from the front and back. Check the signal shape and counting rate. Reverse voltage is applied to the noisy straws There are a couple of channels per module fail the signal test. These wires are removed and re-strung if necessary. Bad wire-joint: front and back are connected No signal: a wire is not connected to a socket Very noisy channel

Signal test output

When modules leave Duke, no more than 1% of straws are dead When modules leave Duke, no more than 1% of straws are dead. The passport has a list of bad wires with reasons for failure. ~1/2 of the wires can be saved with re-stringing. Dimension check Use the fixture from IU to make sure module dimensions are within the specification. Ready for gain mapping.