The TPC Water system skid is 10 m upstream of the TPC
on the west side, next to the BCKOV2 head.
The picture below
identifies the main controls and gauges.
Turning ON the TPC Water
To turn ON the TPC Water:
Turn ON the chiller.
The switch is on the front panel; toggle it up to START,
then release it to ON.
The numeric display shows the current water temperature.
The chiller setpoint temperature is 20°.
To check the setpoint hold down the SETPOINT
button, which displays the setpoint on the numeric display.
To adjust the setpoint, hold down the SETPOINT
button while adjusting the knob. Set it to 20°.
Turn ON the circulation pump.
The switch is the red one on the green motor speed control box
near the floor. Toggle it up to START, then
release it to ON.
The numeric display shows the current pump speed.
The pump speed setpoint is nominally 36, but should be
adjusted to achieve the proper flow rate in step 3, below.
To adjust the speed turn the SPEED knob.
Check the flow rate.
The flow meter above the pump should read 15 gpm.
If it does not, adjust the pump speed as in step 2, above.
Check for leaks.
Take a quick look for leaks:
In the hose connections at the back of the water skid.
In the hose connections at the front of the TPC for
the main supply/return and the cross-over manifolds.
The TPC Low Voltage power supplies are just upstream of JGG
in RR07-RR08 on the east side and RR09-RR10 on the west side.
The pictures below identify
the switches in RR07-RR08.
Turn ON the AC POWER MASTER SWITCH.
The switch is on the 2U panel near the top of RR07.
Reset the CLK and WATER interlocks.
Initially the CLK and WATER lamps
will be lit on the LOW VOLTAGE P.S. MASTER INTERLOCK.
To reset these interlocks, press the RESET button
below each lamp.
Reset the interlock chain for each rack.
At each rack (RR07-RR10), press any RESET button
on any EOS TPC POWER SUPPLY. You may have to hold
the RESET button for a second to get all
the supplies in the rack to latch, or you may need to try
a short press. ;)
Verify that all enabled supplies are on.
The A, B, C, D,
trouble lamps on the LOW VOLTAGE P.S. MASTER INTERLOCK
are illuminated when an enabled power supply channel is off.
When all enabled channels are latched on, the lamps goes off.
Turning OFF the TPC Low Voltage Power Supplies
In the case of
Smoke or
alarming smoke detector
from the Power Supply racks, RR07-RR10;
The VME Crates are located in RR04-RR05 upstream of the JGG
on the east side. The picture below
identifies the switches in RR04-RR05.
Turning ON the VME Crates
To turn ON the VME Crates:
Turn ON each crate using the black switch at the bottom of the front panel.
If the crate does not turn on, check the position of
the red switch on the back, which must also be on.
The Cathode High Voltage Supply is located in RR04 upstream of
the JGG on the east side. The supply is near the bottom of the rack.
The picture below identifies the controls
on the front panel.
Turning ON the Cathode High Voltage Supply
To turn ON the Cathode High Voltage Supply:
Turn ON the Cathode High Voltage Supply using the black power switch
on the left side of the chassis.
Enable the high voltage output, using the red switch on
the right side of the chassis.
Set the current limit to 0.12 mA.
To set the current limit
Press the LIMIT button.
Press the CURRENT button.
Set 0.12 mA on the display using the knob.
Press the ENTER button.
To ramp the voltage in steps:
Press the SET button.
Press the VOLTS button.
Set the desired voltage on the display using the knob.
Press the ENTER button.
Suggested voltage steps and nominal current for a dry chamber with nitrogen gas:
Voltage
(V)
Current
(mA)
100
0.0013
1000
0.0085
3000
0.0245
5000
0.0408
7000
0.0568
8000
0.0647
9000
0.0927
9500
0.0767
10,000
0.0805
After each step, wait for the current to settle to within 0.0002
of the expected value before proceeding to the next step. (The field
cage resistor ladder is 124 MΩ, which sets the current at
each voltage.)
If the supply trips (because of the current limit), it sets the
output to 0 V. You can "catch" it before it gets all the way
down by quickly noting the approximate voltage and entering a new
set voltage that is nearby. For example, if you note the voltage
is 3567 V and dropping, set the voltage to anything in the
approximate range 3000-4000 V and you should be able to clear
the trip and keep the cathode from ramping completely down. Then
restart the step ramp at the next step voltage.
To ramp the voltage continuously:
Press the ADJUST button.
Press the VOLTS button.
Control the voltage directly using the knob.
CAUTION: The knob is rate sensitive.
Small twitches can cause VERY large changes in the setting,
causing the current limit to trip.
". . . the [cathode] need[s] love and a steady hand . . ."
When you reach the desired voltage, press the ENTER button.
To ramp the Cathode voltage automatically:
If not already running (it should be!) start
TPC_Cathode_control on e907hv.
The control program runs only on e907hv.fnal.gov.
To run the program, you have to be the daq user,
and in the right area:
$ su daq
e907hv{daq}:~> cd ~/hv_control/
e907hv{daq}:~> TPC_Cathode_control
Set the voltage and current limits.
There is no read back of the limits. The program displays the last value
set by this invocation. The only reliable way to ensure that the limits
have not been set incorrectly (e.g., by another instance of the program)
is to set them explicitly.
Type L, then enter 10100
when prompted for the new voltage limit.
Type U, then enter 100
when prompted for the new current limit.
Set the voltage to an initial value, by typing V,
then entering 50 when prompted for the voltage.
If the high voltage output is not already ON,
type O (letter 'O') and confirm.
Ramp the voltage by typing P, then enter
the desired voltage. Normal cathode voltage is 10000 (10 kV).
The Anode high voltage supply is the LeCroy 1440 HV chassis
at the bottom of RR05, upstream of the JGG on the east side.
The picture below identifies the switches
on the front panel.
Turning ON the Anode High Voltage Supply
To turn ON the Anode HV supply:
CAUTION: This supply is used by
the T0 counters, the BCKOV counters, the TPC, the CKOV, and
the TOF. Be careful only to modify settings for the intended detector.
Turn ON the AC POWER switch, the large white one
at the bottom of the chassis.
Press the HV ENABLE button, at the center of the
right-hand large module. This should illuminate the READY lamp.
Ramping the Anode Voltage
Note:
The voltage can only be changed using the control program.
The nominal operating voltage is 1300–1350 V, though
some channels only operate stably considerably below this range.
If already running (it should be!) stop
hv_monitor on e907hv.
The control and monitoring programs run only on e907hv.fnal.gov.
They don't share the serial interface nicely, so you have to stop the
monitor program (with a ^C) before starting the control program.
To run the program, you have to be the daq user,
and in the right area:
$ su daq
e907hv{daq}:~> cd ~/hv_control/
e907hv{daq}:~> hv_control
Log in as the TPC Detector (3). Ask a local expert
for the password.
If the mainframe is OFF, turn it on by typing
O.
CAUTION: This will apply voltage to all
the other detectors sharing this mainframe. Check with experts
and/or the weekly coordinator to be sure you should be doing this!.
Load and program the TPC parameters:
Type L to load the parameter file. Enter
tpc-param.hv as the parameter file.
Type P to program the mainframe with the
new parameters.
Check that the anodes have no shorts:
Ramp each card to 20 volts by typing ^R.
The TPC (usually) uses cards 12 and 13.
When prompted, enter the card number, then the voltage
(20).
When the ramp is complete, display the card by
typing C. Verify that each channel has a read back
current less than 5 counts. It make take ~10 for the
read back to settle down, especially if the TPC has been open
to air. Refresh the card display by typing R.
Load the standard voltage file by typing L.
tpc.hv should be a symbolic link to the current
settings. Ask an expert for help in deciding if this file is correct.
Ramp the TPC by typing ^R.
After the ramp is complete, verify that each channel has come
up to the set voltage, and that all currents are less than 10 counts.
Restart the monitoring program, hv_monitor.
Resetting Tripped Anodes
Check that the beam rate is reasonable. T01 should be < 50K
per spill. If the rate is to high, ask MCR to reduce it.
Stop the hv_monitor program and
go to the hv_control program.
Type T to invoke the "Reset TPC" function.
You will be prompted for the new voltage for each tripped channel,
and shown the previous setting. The normal voltage for most
channels is 1250 V.
If a channel trips more than twice in two hours,
reduce the setting by 50 V.
Otherwise, enter the previous setting.
Log in CRL which channels tripped, what voltag they were at,
and what voltage they were reset to.
The TPC gas rack is located upstream of the JGG on the west side,
near to RR09. The picture below identifies
the relevant gauges.
Normally the gas system should only be operated by an expert.
Shifters should check the gas system regularly.
To CHECK the Gas system under normal flow conditions:
Verify that the raw supply pressure on PI-01
is in the 3-7 psi range.
Verify that the regulated pressure on PI-03
is in the 1.8-2.2 psi range.
Verify that the TPC inlet pressure on PI-02
is in the 0.45-0.5 inches of water range.
If this pressure is
> 1 inch of water
then turn off the Gas system.
Verify that the TPC outlet pressure on PI-04
is in the 0-0.2 inches of water range.
If this pressure is
> 1 inch of water
then turn off the Gas system.
Verify that the rotameter ball on FI-01
is in the 100-120 mm range.
Verify that the MAIN BUBBLER, B1 is actively bubbling.
![[Image: Photo of Chiller Sled with controls labeled.]](H20_Chiller_Sled.jpg)
![[Image: Photo of RR07-RR08 with controls labeled.]](EOS_Low_Voltage_PS.jpg)
![[Image: Photo of RR07-RR08 with controls labeled.]](EOS_Master_Interlock.jpg)
![[Image: Photo of VME Crates with switches labeled.]](VME_Controls.jpg)
![[Image: Photo of Cathode High Voltage Supply.]](Bertan_HV.jpg)
![[Image: Photo of LeCroy 1440 High Voltage supply.]](LeCroy_HV.jpg)
![[Image: Photo of TPC Gas Rack with valves and gauges labeled.]](Section_Controls.jpg)