Resonant Elastic and Inelastic X-ray Scattering (REIXS)
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Resonant Elastic and Inelastic X-ray Scattering (REIXS)
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RIXS Cryostat Operations

The RIXS endstation is equipped with a flow cryostat. Below are brief instructions on how to operate the cryostat.

HANDS ON TRAINING BY BEAMLINE STAFF IS REQUIRED

Initial Cooling Down

  1. Ensure the needle valve is fully closed and the N2 gas valve is open with the dewar pressure set to 3.5 psig.

    1. The regulator may need adjusting, set the regulator to align the red marks.

  2. One pressure of 3.5 psig is achieved, open the need valve 4 turns.

    1. You will need to support the transfer line and loosen the tube sealing nut

    2. Unscrew the base tube 4 turns.

    3. Re-tighten the tube nut.

  3. Allow the sample holder too cool down, this will take approximately 20 minutes.

    1. There is generally a 20-30 K gradient between the cold finger and the sample temperature.

  4. Once the temperature is fluctuating wildly (the cold finger temperature will around 100 K) close the cryostat to 2 turns.

    1. This will take another 20 minutes.

    2. This indicates you have liquid in the cold finger and you are getting rapid boil off.

    3. If you do not reduce the needly valve, LN2 will start coming out the vent.

    4. Reduce the dewar pressure to 2.0 - 2.5 psig, align the black marks on the regulator.

  5. Once minimum temperature (~78-79K) is achieved, close the needle valve to approximately 1 turn, align the black marks on the needle valve nut.

    1. This may need to be tweaked depending on the dewar level, which will affect the overall flow.

    2. Allow the LN2 flow to stabilize for 15 mins.

  6. Set the sample temperature to 90K and wait for the temperature to stabilize.

    1. Ensure the heater power is approximately 30-40% (medium loop).

      1. Adjust the needle valve to achieve this if necessary. It also depends on dewar pressure.

  7. Adjust sample temperature as desired.

Rapid Re-Cooling Sample

  1. Set the sample temperature to 80K.

  2. Open the needle valve 2-3 turns until the cooling rate is sufficient.

    1. One you achieve base temperature, close the needle to the original position.

Heating of Sample

When changing the temperature of the sample, you will always see some outgassing when heating, relatively. Always make sure:

  1. Turn off the beam when changing temperature.

  2. You adjust the sample temperature by small amounts, less than 50K.

    1. Watch the sample chamber pressure and ensure is stays < 1 X 10e-08 Torr.

  3. When heating above ambient conditions, move upward in 10K steps and keep and monitor the vacuum.

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