MDM

Prerequisites

 * 1) Make sure that the "Sol Switch" on the gas handling system (mounted to the back of the MDM) is in the ON position.
 * 2) Ensure that the roughing pump on top of the MDM is running. It’s controlled by a power switch in the breaker panels near the center of the spectrometer. If the pump is not on, first ensure that the appropriate valves are closed before turning it on (see the step 4 for details). This pump roughs out both the MDM chamber and the detector chamber (controlled by separate valves, see step 4), as well as the small volume between the exit window and the scintillator (which is coupled to the MDM chamber).
 * 3) The LN2 trap should be in place and filled with liquid nitrogen (the purpose of the trap is to prevent back-filling of pump exhaust into the chamber).
 * 4) The roughing pump pumps through four valves (pictured below); all should initially be closed:
 * 5) Silver butterfly valve (closed is with the notch perpendicular to the vacuum line). This valve controls flow from the pump to all points downstream.
 * 6) "Pin" valve. This valve blocks flow to the MDM chamber. It is only used as a coarse on/off, not a fine adjustment.
 * 7) "Orange handled" valve. This also controls flow to the MDM chamber. It is used as the fine adjustment of pumping rate to the chamber.
 * 8) Black butterfly valve. This controls flow to the detector chamber. It is used for fine adjustment of the pumping rate (there is no coarse valve for this chamber).

Roughing Procedure

 * 1) Ensure that all four roughing valves described in the previous section are closed.
 * 2) Open the silver butterfly valve; this allows pumping up to all of the others.
 * 3) Open the "pin" valve fully to allow coarse access to pumping the MDM chamber.
 * 4) Partially open the orange handled valve to allow pumping of the MDM chamber. There is a mark drawn on the sides of the valve that indicates the approximate position to which this valve should be opened (see photo below).
 * 5) Slowly open the black butterfly valve to start pumping the detector chamber. Read the paragraph below if you are doing this for the first time. This is the important and crucial part where things (e.g. windows) can be broken.

Controlling the Pumping Rate
The pumping rate to the MDM and detector volumes is controlled by the orange handled and black butterfly valves, respectively. Care needs to be taken to ensure that the appropriate pumping rates are in effect, so that the entrance/exit windows of the detector are not broken. Your goal when adjusting the pumping rates is twofold:
 * 1) Keep the rate of pressure drop on the detector volume to less than one torr/second. This pressure is read out by the black digital gauge on the gas handling system (photo below).
 * 2) Keep the rate of pressure drop on the detector and MDM volumes roughly the same. The pressure on the MDM volume is read out by an analogue gauge (units: bar or in-HG; conversion to Torr is ×750 or ×25.4 respectively). Typically you will want to do this part with two people, so that one can watch the MDM volume pressure gauge and the other can adjust the black butterfly valve.

You should also monitor the pressure in the small volume before the scintillator; there is a separate gauge for this as well, though it doesn't work very well. In principle this should drop along with the MDM chamber, unless there is a leak.

Starting the Turbo

 * 1) Ensure that the gate valve to the MDM chamber is closed.
 * 2) Isolate the chamber from the roughing pump by closing both butterfly valves (black and silver).
 * 3) Open the valve to the backing line (see photo).
 * 4) Pump the backing line until the pressure (read from black box gauge in the photo) is reading ~30 microns.
 * 5) Start spinning the turbo (photo of turbo control box below):
 * 6) Flip the on/off switch to "1"
 * 7) Flip the start/stop switch to "start".
 * 8) Let turbo spin up (LED indicator goes from yellow to green).
 * 9) If the chamber is still below the interlock condition to open the gate valve (< 100 microns on gauge 1 on the interlock panel), open the gate valve to the turbo (from the interlock panel - see photo), and you are done. If not, you will need to reduce the chamber pressure again by doing the following:
 * 10) Do this step all in rapid succession: Close backing valve, open both butterfly valves (silver, then black).
 * 11) Wait for pressure in the chamber to come down to below 100 microns (give some breathing room).
 * 12) Close the butterfly valves, open the backing valve, let turbo spin up.
 * 13) As soon as the turbo spins up, open the gate valve from the interlock panel (it helps to have two people for this step - one watching the turbo to yell to the other when to open the valve).

Note: If the interlock conditions don't match the actual pressures (e.g. the interlock panel won't let you do things you should be able to), reset the panel by pushing the "Reset" button and toggling the "Reset" key.

Venting the MDM

 * 1) Close turbo gate valve from the interlock panel.
 * 2) Vent the section w/ the LN2 trap from the manual vent valve near the trap.
 * 3) Open the orange valve all the way to couple the MDM and detector chambers.
 * 4) Connect a dry nitrogen line to the vent valve (pictured) and start venting. Open slowly to protect the windows (keep rise rate < 1 Torr/sec).

Prerequisites

 * 1) Turn on the roughing pump "K32" (pictured) at the interlock panel ("Mech pump" label). This pumps the gas handling system and bottle.
 * 2) Check that the permissions on the interlock panel will allow you to open the solenoid valve. This is the valve that controls flow from the gas bottle and can be operated remotely in the control room.

Flushing the Gas Line
After checking the pre-requisites you will need to flush the gas lines:
 * 1) Isolate the detector by closing the orange-handled valve and ensuring that all valves on the gas handling panel are closed.
 * 2) Open the solenoid valve from the interlock panel.
 * 3) Open the small black valve near the bottle, pump for 30-60 seconds, then close.
 * 4) Open the large black valve near the bottle
 * 5) Open the main valve on the bottle, check the regulator to see gas is flowing, leave open for ~15 seconds, then close.
 * 6) Open the small black valve again, wait 30-60 seconds, close.
 * 7) Repeat steps 5 & 6 six more times to completely flush the lines.
 * 8) Once you are finished, close the small black valve and leave the main valve open.

Filling the Detector
Filling the detector will be done from the gas-handling system panel, mounted to the back of the MDM. Pressure is monitored from the reading on the black MKS unit (pictured). Before starting, ensure that the "input" range switch is set to 10 kV - this will give a pressure reading in Torr.

The steps to fill are:
 * 1) Open valve "B1" valve fully.
 * 2) Open "G3" valve fully.
 * 3) Turn the knob on the left of the controller ("EXT. SET PT." - see photo) to the setpoint you want (the number on the dial should be the setpoint in Torr). Call this the "setpoint" knob for future reference.
 * 4) Set the lower silver knob on the right hand side of the controller (see photo) to "MAN." (for manual control).
 * 5) Dial the black knob on the RHS of the controller up (call this the "flow rate" knob from here on out), to start letting gas flow into the detector. Turn the knob slowly to ensure that the fill rate is less than 1 Torr/second.
 * 6) Note Usually this needs to be beyond ~100 before the pressure starts to react, and there is a bit of lag between changing the knob and a change in the fill rate.
 * 7) As the pressure starts to get close the the setpoint, dial back the flow rate knob until the ball in the flow rate indicator is roughly halfway to the full range.
 * 8) The next step is to start opening valves to pump on the "out" side of the detector. This is a delicate balancing act, so it has it's own sub section.

Finding the Right Pressure
As mentioned, getting the pressure to stabilize is a delicate balancing act. What you are doing is adjusting the flow rate both into and out of the detector, so that it stabilizes at the desired pressure. To do this, you can twist "knobs" on both the input and output sides of the equation: on the input side you have the "setpoint" knob and on the output side you have two new valves: valve "G2" and "Needle Valve" (both labeled as such on the panel).

The first step is simply to start letting pumping happen on the output side:
 * 1) Open valve G2 - not fully but to the point marked on the valve/panel.
 * 2) Open the needle valve. There are some tick marks drawn on the panel to indicate how much it is open. Roughly 7 ticks is a good place to start.

From here, you will need to keep adjusting the needle valve and/or out flow valves until you've reached stable flow, i.e. when the pressure is stable st the point you want it and the flow rate isn't fluctuating too much (small wiggles are okay, but not wiggles across the full flow range). This can be a tedious process - more an art than an science - and something requiring some practice.

Once things are stable on the manual setting, you will need to switch the silver knob on the RHS of the controller over to "AUTO". When you do this, the stability will probably be destroyed. The next steps are to iterate the procedures you already followed for balancing the pressure and flow rate on the manual setting, until they are stable on the AUTO setting. Again, this is a tedious process that requires some practice and patience.

Once things are finally stabilized to your satisfaction (pressure stable where you want it, flow rate only fluctuating by small/moderate amounts), you are finished. Continue to monitor the pressure/flow rate with cameras during the experiment.

Emergency Notes
If at any time, the flow rate becomes too high (significantly above 1 Torr/second), immediately switch the solver RHS know to "CLOSE". This stops all flow to the detector and preserves the windows.

Emptying the Detector
The detector should be emptied any time it is not actively being monitored. For safety reasons the detector should not be left unmonitored with gas in the chamber. A burst window with gas flow connected creates a potential fire/explosion hazard from isobutane being pumped into the cave.

The steps to empty the detector are as follows:
 * 1) Flip the silver RHS knob on the gas flow controller to CLOSE.
 * 2) Close the gas in valves (B1 and G3), but leave the gas out valves (G2 and Needle) open.
 * 3) The step above starts pumping the chamber through RP "K32".
 * 4) You can open valve G2 more if you want, to speed up the pumping rate (just be sure to keep it below 1 Torr/second).
 * 5) Once the pressure in the detector chamber reaches 1 or 2 Torr, you can open it up to the main MDM volume, to begin pumping with the turbo. This is done by slowly and carefully opening the orange handled valve, connecting the main volume to the turbo. As the pressure drops to safe levels, you can slowly open the orange valve all the way, and you are done.

If you open the valve too fast in step 3, the GV between the turbo and the chamber will trip. In that case, you can rough out both chambers together to get the pressure down to below 100 microns on the interlock panel, then follow the normal procedures for starting the turbo.