On the LakeShore thermometer:
channel 1: LN2 dewar temp.
channel 2: LHe dewar temp.
channel 3:The work surface temp where the detector is mounted.

Under NO circumstances should the fill line caps be left off for any length of time without a fill line installed. This is especially true of the LHe fill line; if you need to stop the fill temporarily to get a fresh LHe storage dewar, to locate some missing part, or for any reason, recap the fill line until you are ready to resume the fill.

Filling the LN2 dewar

• Rotate NIRC to the fill position as indicated on the back of the forward cass module.
• Connect the LakeShore thermometer cable to the T1 socket on NIRC.
• Turn on thermometer and record temperatures. If the dewar is at LN2 temp, channel 1 should read 80 K, channel 2 should read 80 K, and channel 3 should read 80 K. If the dewar is at LHe temp, channel 1 should read 80 K, channel 2 should read 4 K, and channel 3 should read between 4 and 30 K. If the temperatures do not read within 1 degree of what they should, notify an instrument technician or instrument specialist immediately.
• Attach the transfer line to a 170 liter storage dewar, if not already attached.
• Flush the line of air by opening the storage dewar valve for ~ 10 seconds.
• Remove cap from dewar LN2 fill port and plug in transfer line until it seats. TO PREVENT ICE PLUGS, DO NOT LEAVE THE CAP OFF THE LINE FOR MORE THAN 5 SECONDS.
• Screw down retaining ring lightly.
• Slowly start to open storage dewar valve. If relief valve starts to open, close the storage dewar valve until relief valve shuts. As line and dewar cool the storage dewar valve can be opened somewhat more before relief valves open.
• Continue filling dewar LN2 tank until liquid starts to exit from the NIRC vent line.
• Shut storage dewar valve.
• Remove transfer line from dewar fill port and quickly put the cap on. TO PREVENT ICE PLUGS, DO NOT LEAVE THE CAP OFF THE LINE FOR MORE THAN 5 SECONDS.
• Log the job in the summit instrument activities schedule on the web.

Warm LHe Fill (Filling LHe when at LN2 temperatures)

• Plug in the scale at the AC outlet and record the weight of the LHe dewar.
• A LHe fill, with the LHe dewar at or near LN2 temperatures requires ~ 5 lbs of LHe. Most LHe storage dewars are marked stop@ on the side. Do not attempt to fill if the dewar weighs less than 3 pounds over the stop@ value. If the dewar does not have a stop @ label, if it is less than 6 lbs above the empty dewar weight, get a fresh LHe dewar! The empty dewar weight is the tare weight (T.W.) without the transfer line connected or is the tare weight plus the weight of the transfer line (5.3 lbs.)
• If the vacuum jacketed LHe transfer line is not already in the LHe storage dewar, close the valve gently and insert it in the dewar slowly.
• Rotate NIRC to the fill position as indicated on the back of the forward cass module.
• Connect the LakeShore thermometer cable to the T1 socket on NIRC.
• Attach the Cryomagnetics 1200 S/H LHe level sensor cable to socket L1 on NIRC dewar.
• Turn on thermometer and record temperatures.Channel 1 should read 80 K, channel 2 should read 80 K, and channel 3 should read 80 K. If the temperatures do not read within 1 degree of what they should, notify an instrument technician or instrument specialist immediately.
• Turn on the LHe level sensor box and set to continuous readout. The level should near zero.
• Flush the air out of the LHe transfer line by opening the transfer line valve for ~10 seconds.
• Remove cap from dewar LHe fill port and plug in LHe transfer line until it seats. TO PREVENT ICE PLUGS, DO NOT LEAVE THE CAP OFF THE LINE FOR MORE THAN 5 SECONDS.
• Screw down retaining ring.
• Slowly start to open storage dewar valve. If relief valve starts to open, close the storage dewar valve until relief valve shuts. As line and dewar cool the storage dewar valve can be opened somewhat more before relief valves open. A relatively slow cool down and fill conserves LHe.
• When channel 2 of the thermometer, the LHe temperature, reads about 5 K to 6 K the tank will start to fill with LHe.
• Fill the tank until it reads 94% (the level sensor reads in %)or until there is evidence that liquid has reached the vent line.
• Close the transfer line gently.
• Promptly set the level sensor to sample mode from continuous mode.
• Disconnect the LHe transfer line and quickly cap the fill port. Tighten the cap fully. TO PREVENT ICE PLUGS, DO NOT LEAVE THE CAP OFF THE LINE FOR MORE THAN 5 SECONDS.
• Record the LHe level (percentage full).
• Record the channel 2 temperature. It should be 4 K.
• Record the weight of the LHe dewar. Unplug the scale so the light will not affect observing.
• For refilling the dewar with LHe, see the instructions for doing a cold LHe fill (Filling LHe when at LHe temperatures).
• To remove the thermometer or the level sensor, first turn it off then unplug the sensor cable from the dewar level shifter box, T1, or L1.
• Log the job in the summit instrument activities schedule on the web. In the comments section, record in the following format : channel1 temp, channel2 temp, channel3 temp, the starting weight of the dewar-the end weight of the LHe dewar, The starting percentage of LHe-The end percentage of LHe, and channel 2 after the fill.
• If the LHe dewar is empty, change the tag to "empty" and bring it to shipping and receiving. Bring a fresh dewar up to the Nas deck, change the tag to "in service" and install the transfer line.

Cold LHe Fill (Filling LHe when at LHe temperatures)

• Plug in the scale at the AC outlet and record the weight of the LHe dewar.
• A LHe fill, with the LHe dewar at LHe temperature requires ~ 2.5 lbs of LHe. Most LHe storage dewars are marked stop@ on the side. Do not attempt to fill if the dewar weighs less the stop@ value. If the dewar does not have a stop @ label, if it is less than 2.5 lbs above the empty dewar weight, get a fresh LHe dewar! The empty dewar weight is the tare weight (T.W.) without the transfer line connected or is the tare weight plus the weight of the transfer line (5.3 lbs.) if connected.
• If the vacuum jacketed LHe transfer line is not already in the LHe storage dewar, close the valve gently and insert it in the dewar slowly.
• Rotate NIRC to the fill position as indicated on the back of the forward cass module.
• Connect the LakeShore thermometer cable to the T1 socket on NIRC.
• Attach the Cryomagnetics 1200 S/H LHe level sensor cable to socket L1 on NIRC dewar.
• Turn on thermometer and record temperatures. Channel 1 should read 80 K, channel 2 should read 4 K, and channel 3 should read between 4 and 30 K. If the temperatures do not read within 1 degree of what they should, notify an instrument technician or instrument specialist immediately.
• Turn on the LHe level sensor box and set to continuous readout. Record the percentage full.
• Flush the air out of the LHe transfer line by opening the transfer line valve for ~10 seconds.
• Remove cap from dewar LHe fill port and plug in LHe transfer line until it seats. TO PREVENT ICE PLUGS, DO NOT LEAVE THE CAP OFF THE LINE FOR MORE THAN 5 SECONDS.
• Screw down retaining ring.
• Slowly start to open storage dewar valve. If relief valve starts to open, close the storage dewar valve until relief valve shuts. As line and dewar cool the storage dewar valve can be opened somewhat more before the relief valves open. A relatively slow cool down and fill conserves LHe.
• Fill the tank until it reads 94% (the level sensor reads in %)or until there is evidence that liquid has reached the vent line.
• Close the transfer line gently.
• Promptly set the level sensor to sample mode from continuous mode.
• Disconnect the LHe transfer line and quickly cap the fill port before LHe escapes. Tighten the cap fully. TO PREVENT ICE PLUGS, DO NOT LEAVE THE CAP OFF THE LINE FOR MORE THAN 5 SECONDS.
• Record the LHe level (percentage full).
• Record the weight of the LHe dewar. Unplug the scale so the light will not affect observing.
• Turn off the level sensor and the LakeShore thermometer.
• Unplug the sensor and thermometer cables from the T1 and L1 ports on the NIRC dewar.
• Log the job in the summit instrument activities schedule on the web. In the comments section, record in the following format : channel1 temp, channel2 temp, channel3 temp, the starting weight of the dewar-the end weight of the LHe dewar, The starting percentage of LHe-The end percentage of LHe.
• If the LHe dewar is empty, change the tag to "empty" and bring it to shipping and receiving. Bring a fresh dewar up to the Nas deck, change the tag to "in service" and install the transfer line.

• For non-routine NIRC fill procedures, see http://www.keck.hawaii.edu/realpublic/inst/nirc/engineering/Cryogens.html