1993/03/10

Here are instructions for cooling the SONIC.

1. Attach vacuum valve to pump, start pump.  When pressure on-scale
on gauge, open dewar valve.  Wait until pressure is below 5x10^-4;
below 2x10^-4 is even better.

2. Attach helium hoses to cooler if not already done.  Note order
specified on cold head.

3. Find a 12 volt power supply, Vac-ion power supply, the 4-pin
connector with two orange wires coming out, and the bias cable (19
pin connector on one end, D-15 plus 4-pin plug on the other).  If you
want to monitor temperatures during the cooldown and don't have the
camera electronics, also find the adaptor with D-15, D-9, and round
26-pin socket all wired together.

4. Start the compressor.  Make sure the water valve is plugged in and
that cold water is flowing in the compressor.  In cold weather, the
compressor is hard to start.  Let it run 10 seconds, then stop for 10
seconds, then 20 seconds, etc.  Soon it should be running continuously.

5. Attach the bias cable to the dewar.  Plug the 4-pin connector into
the socket with the orange wires, connect the orange wires to the
power supply, turn on supply, and set to 12 volts.  Check that the
current is approximately 110 mA.

6. To monitor temperature, turn on temperature controller and attach
to dewar.  This can be either via the plug on the camera electronics
or via the "three-connector adaptor."  If using the latter, plug the
bias cable from the dewar into the D-15 on the adaptor.  The round
plug on the adaptor goes to the dewar, and the D-9 goes to the
thermometer cable on the DRC-91 temperature controller.  Channel A2
is the detector block, A4 is the cold shield.  The temperature of A2
should never change faster than 1 degree per minute.  Following these
instructions should ensure that.

7. When the temperature of A2 has dropped to approximately 150 K, it
should be possible to plug in the Vac-Ion.  This will be 3-5 hours
after the cooler is started.  After another hour or two, when the
temperature has dropped to 120 K or so, it should be possible to
close the vacuum valve.  The valve will need to be closed and
reopened a couple of times to clear out air trapped in the valve
itself.  Make sure the Vac-Ion pump stays on-scale with the valve
closed.  When it does, the vacuum pump can be stopped and
disconnected. 

8. When temperature A2 is below 100 K, the power supply voltage can
be reduced to 6 V.  After half an hour at 6 V, the power supply can
be disconnected if desired.  Or it can be left at 12 volts as long as
you like.