Trials for the testing technology

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Trials for the testing technology
UCL

• Robert L. Flack

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Test cell

• The cell has to have a full complement of wires.
• Need to be able to remove and replace all of the
  wires, hence also want spares.
• Require five ports for lenses.
• Require holes next to each port to insert fibre
  optic.
• The length has to be four metres, or whatever the
  agreed length is to be used in Supernemo.

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Purpose and basis of the trials

• First purpose of the trials is to find the best
  and most efficient method for triggering the
  plasma for our final testing procedure.
• Secondly to trial the best combination of
  cleaning methods.
• Thirdly to build experience with these various
  techniques.
• The proposed method of comparing one technique
  against another is to run each trial many times
  and record the size of the pulse from the plasma.
  The heights of these pulses should fit a
  Gaussian. The values of the mean and width for
  each trial will be compared.
• Another factor could be the quality of the shape
  of the pulse.

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Triggering the plasma

• Obtain propagation of the plasma with cosmic
  rays. Separate these into triggers from the five
  regions of the anode wire.
• Demonstrate triggering of the plasma with the
  UV-laser from the same five regions.
• Use lenses with different focal lengths to test
  triggering at different depths in the cell
  between anode and cathode.
• Demonstrate triggering using optical fibre rather
  than a lens.

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Cleaning the wires with heptane

• The purpose of the tests on various cleaning
  methods is to try and judge what is the best
  combination to obtain the largest average pulse.
• Use unclean wire or deliberately contaminate the
  anode and see if the position of the
  contamination can be found.
• Try heptane to clean it.
• Will this be sufficient?
• Try alternatives to heptane to judge their
  effectiveness.

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Test the baking technique

• Build an oven and trial the baking technique.
• The nemo3 TDR reported using a temperature of
  650oC.
• Bake contaminated wire and see if this will be
  sufficient without first cleaning with heptane.
• Try cleaning with heptane and then baking it and
  again.

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Nitrogen jet

• Blow a jet of nitrogen along the length of a
  contaminated anode wire and test to see if it
  will propagate a plasma.
• Then take wire cleaned with heptane but will not
  support a plasma and see if this technique will
  cure the problem.
• Then take wire that has been both cleaned with
  heptane and baked.

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Testing the tension on the wire

• As a separate problem the best method of
  measuring the tension of the wire during
  construction and in situ.
• During the wiring process a mechanical method is
  probably best.
• In situ an electrical method will be trialed.
• These have yet to be finalised.

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Conclusion

• Need a clean environment to do these trials.
• Many and varied trials to be done and will take a
  lot of time. Need to get started!
• Need to finalise the methods for measuring the
  tension on the wires.
• Could also start preparing the ground for
  automatic electronic readout.
• I will document the trials for circulation and
  will be placed on my website.