Saclay Drift Chambers - Operating instructions
Contents
1. proportion is either 0 no flammable gas or 45 during data taking Note equalizing the fluxes may need to slightly change the 45 value Change also the CF4 proportion if needed Push the ESC button and check that the both Ar and Ethane flows are equal If not adjust the Ethane proportion 45 22. 16 June 2008 Saclay Drift Chambers Operating instructions 1 General Three Drift Chambers DCs detectors are in use DCO DC1 and DC4 The DCO and DC1 detectors are identical each detector has an active area of 127x 180 cm and consists of 8 layers of sensitive wires X X Y Y U U V V The total gas volume per detector is 250 1 The DC4 detector has also 8 layers of sensitive wires However its active area is larger 248x208 cm DC4 has a total gas volume of 700 1 All detectors are fully efficient at operating voltages of about 1700 1750 V All DCs use the same gas mixture Ar 45 C2H6 45 and CF4 10 The gas flow and mixture for all three DCs is set via the touch screen of the PLC3 located in the Gas Area The HVs are set using the Saclay Slow Control software Saclay barrack on top of the Gas Area Phones Saclay on call 16 0731 A Magnon 163943 2 Start up of DCs operational gas flow a Make sure that all gas pipes are connected This should be the default situation during both beam time and winter shutdown b Purge detectors with Argon changing 4 times the chamber volume requires 5 days for DCO DC1 and 14 days for DC4 c Perform leak test for all 3 detectors using Argon gas only The leak test has to be made at least once per year before the run d Open the MM DC ethane valve in flammable gas arrival rack Check whether the MMs detectors are also ready they share the sa
3. me valve e Set the ethane fraction to 45 in PLC3 See PLC3 instructions on next page Set the CF fraction to 10 g Changing 4 times the chamber volume requires 5 days for DCO DC1 and 14 days for DC4 Note High Voltage must be turned ON only after the gas mixture is close to nominal 3 Purging flammable gas and shut down of DCs a Set High Voltage OFF Slow Control commands are in the COMPASS control room or Saclay barrack b Set the ethane fraction from 45 to 0 in PLC3 See PLC3 instructions on next page c Set the CF4 fraction to 0 in PLC3 See PLC3 instructions on next page Close the MM DC ethane valve in flammable gas arrival rack if MMs detectors have also been prepared for this operation Purge completely all 3 chambers with Argon changing 4 times the chamber volumes takes 5 days for DCO DC1 and 14 days for DC4 4 Operation a b C DCs gas flows and mixtures are controlled by PLC3 and by the bubblers in the MM DC gas rack DCs High Voltage and threshold settings are controlled by the COMPASS slow control For Slow Control commands go in the Saclay barrack Check the 3 DC bubblers twice per shift Normal bubbling is in the range 0 3 0 6 Hz 5 PLC3 operation moeepooe a On the touch screen select DC Push the MENU button Push the R4 box in order to enter the password Type the password 6535 and then push ENTER Push the ESC button Select the R1 button Ethane proportion This
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