Preliminary setup and change of the dewar should be done together with a beamline scientist. This instruction is only for the case when the needle valve is already inside the dewar.
Check that helium line is deep inside the dewar, ca. 5 cm above the bottom.
Check that Helium pump is running (see panel inside the frame from the side of the load lock):
3. Check that black valve below the frame is open:
4. Make sure that helium recovery line is connected to a He return port on the wall-panel.
5. Use ladder and open the needle valve 1 full turn. Rotate counter clockwise if you look from below.
6. Wait until temperature reading starts to steadily go down by 0.01 K. If this doesn't happen in 10 minutes - it is likely that there is a problem (*).
7. When sample temperature reaches ca. 40K start closing needle valve in small steps and wait for the temperature to stabilize. Try to close as much as possible to reduce helium consumption, but don't let temperature to go up.
8. The lowest temperature reading is ~12-20 K.
To reach the lowest possible temperature on the sample one can improve thermal contact by tightening the screws on the sample pocket of manipulator head. See here for more details.
Check that helium line is not at the very bottom of the dewar. If it slides down, retract at least 5 cm back. This way there is less chance that it will freeze inside.
Make sure that the needle valve part is straight, if not - adjust the support.
Underpressure in the LHe dewar should be avoided at all times! If this happens, air can reach inside the dewar and moisture will turn into ice that freezes on cold parts inside. This ice can block helium line from moving, then it cannot be neither closed normally nor taken out to change the dewar. Too much ice may lead to a dangerous condition!
(*) As a first step try to disconnect helium recovery line from the wall and check if there is a flow of gas coming out of it.
The screws on the manipulator head (left photo) can be tightened to provide a better thermal contact while cooling for the samples that require lowest possible temperatures. Vacuum screwdriver is located in the Preparation Chamber, close to the heater (right photo).
Move manipulator to preparation chamber;
Close the valve between the chambers;
Go to a saved position "screwdriver" or rotate manually tilt and polar angles;
Do not apply force! Just screw until the end without making it too tight;
Return to "Transfer_PREP" position.
To take your sample out later you will need to loosen the screws by ca. 2 full turns.
Using manipulator heater to set sample temperature
Make sure that Contol A LED is on (the coldfinger temperature will be used as a reference).
On the Lakeshore TC press Setpoint button (6).
Dial in the desired temperature for coldfinger (A)*. Sample temperature will be ~10 deg higher.
Press Enter.
Press Heater Range button and select power. Start with low, if it is not enough - try medium.
Press Enter.
Find below an approximate table of correspondence between A and B temperatures.
10
19.5
low
18
25
?
24
30
med
29
35.2
med
33.1
40
med
37
45
med
41
50
med
45.3
55.2?
med
49
60
med
57
70.5
high
85
100
high
