This is a brief summary as of how to operate the cryogenic part of the system.

1. Reading temperature. 

There are three relevant thermometers in the IVC.

Diode on the sorption pump (used mostly when condensing he3),
calibrated 4K-room. The measurement is two-wire. The current through it (BNC
marked SP diode) should be 10 microamp, and an y of the voltmeters should be
connected in parallel to it. Calibration table is in the book and on the
computer through configtemp-showtemp procedure. It's name is sp.


Allen-Bradley 100 Ohm resistor on the 1K Pot.
Calibrated 1K-room, but good 1K-100K
Four-wire measurement, connected on the string IVC i in on the temperature 
measurement box. The voltmeter should be hooked up to the "AB" banana outlet.
The current can be set to 1 to 100 microamp. When using the computer to read 
the temperature, the currents setting should be put in as variable Iref (In fourc,
just type Iref=1e-4 for 100 microamp). Settings of 10 microamp or less should be 
used below 4K. Calibration is in the book and on the computer through showtemp.
The name of it is ab.

Germanium thermometer on the .3 K stage - used for actual sample temperature 
readings.
Calibrated .1K to 77K, but good from .3 to 20K.
It is on the same IVC string as the Allen-Bradley, and the voltage should be
drawn from the banana outlet marked GE. Calibration is in the book and on the computer
The name is ge.


Current source and reference voltage.
There are two current sources Current 1 and Current 2 providing current of 1, 10 or
100 micro-amps. Unfortunately, after they stopped producing mercury 1.5V cells (for 
reasons of safety), we are using alkaline batteries which drift a bit with time. 
If the precise measurement is a must, the current sources should be re-calibrated,
or the reference voltage should be read and recorded in the book. Also, it is possible 
to instruct the computer to use the reference voltage.
To read the reference voltage, connect a voltmeter to the banana plugs on top of the 
temperature box (I have to fix it permanently one day). The value of the reference
resistor is 999.97 Ohm and does not drift much


Using the temperature measuring macro hetemp.mac

The macro allows one to record the temperature and voltage readings into the spec
data file, and allows to read the voltages and convert them to temperature automatically.

To start the macro, type do /usr2/harvard/macros/hetemp.mac
To get the gpib settings correctly run gpib.mac in the data directory AFTER
the hetemp.mac was run. This is needed because the gpib settings may change as we swap
devices.
After that has been done, run configtemp and enter the appropriate names for the 
thermometers. 
Change Iref if needed (type Iref=....)
To read the temperature, type showtemp, or te

Pressure gauge and lock-in.
Capacitance pressure gauge is connected to the GR bridge with two coaxials
(unknown L and H). The AC signal from the lock-in's generator plugs into
"generator" banana plug. The "Detector" outlet of the bridge connects to the 
input of the Lock-In (input A)