Barrel TRT Straw QC: Resistance and Straightness

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Barrel TRT Straw QCResistance and Straightness

• K. McFarlane
• Hampton University
• DOE/NSF Review, BNL March 2001

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Summary

• With more than 12,000 straws processed, very few
  are rejected by the Hampton straw straightness
  test or the inner winding resistance test
• The straws are tested for straightness at PNPI
  and JINR before being sent to us
• Indiana and Duke make a measurement of resistance
  during installation
• The tests are done at the Straw Final Cut Station
• It is proposed to drop these QC steps at Hampton.

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Straw Straightness and Resistance Tests
Straightness
Resistance
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Straightness Parameters
The PNPI/JINR criterion is different from
Hamptons. For a simple arc, though, the
criteria are equivalent. (TDR is sagitta
lt1mm.) For a simple arc, the offset between
dividers will be 1/72 of the double sagitta for
3mm, 40 mm. The maximum out-of-straightness is
300 mm, from all variations, to keep the gain
variation lt5, and the discharge rate low.
Barrel TRT
PNPI/JINR
doublesagitta
lt3mm
lt 8mm
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Straw Straightness Results
The table shows the number of straws binned by
measured double sagitta, bins in mm (lt0, lt0.5,
etc.) Only 8 straws out of 11k exceed 3mm double
sagitta. These exceed the criterion by
lt1mm. This will have a negligible effect on gain
variation.
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Inner Winding Resistance

• The inner winding resistance is specified (TDR
  Vol 2, p.622) to be lt300 ohm/m. For the barrel,
  that is roughly 430 ohm.
• At Hampton we use a cut-off of 400 ohm.
• The main variation is due to contact resistance
• At Duke and IU, measurements are made with better
  contacts, for module diagnostic reasons.

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Inner Winding Resistance
Very few straws exceed 400 ohms.The 4 listed are
almost certainly typos.
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Conclusion

• Resistance test at Hampton is unnecessary