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Application of the Beta-ray alignment for the OPERA CSDs

Application of the Beta-ray alignment for the OPERA CSDs. Seigo Miyamoto. Beta-ray alignment. New alignment method by using beta-ray from environmental radioactive isotopes. Coincidence at contacted emulsion layers.

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Application of the Beta-ray alignment for the OPERA CSDs

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  1. Application of theBeta-ray alignment for the OPERA CSDs Seigo Miyamoto

  2. Beta-ray alignment • New alignment method by using beta-ray from environmental radioactive isotopes. • Coincidence at contacted emulsion layers. • Effective to correct the distortion( is essential for good position resolusion) of film by development or drying .

  3. Detection ofposition displacement peak of beta-ray -Take all combination of dx in ~+-100um - Angle allowance is FREE. 2.1um 1.8um

  4. If the tightness of packing is enough, Position displacement of high energy tracks from beta-ray alignment peak (um)

  5. Application for the OPERA CSD • Alignment accuracy is less than 1um. • Effective to reject BG tracks very much. Samples : Cosmic run events ---- 26 CSDs Neutrino events ---- 32 CSDs

  6. At first, division of area (5mm x 5mm)

  7. Procedure Taking all combinations of MicroTracks in contacted layers, And Detection of beta-ray alignment peaks in each unit areas. Position displacement distribution from the X-ray alignment

  8. Plot vector as the center of peak in each unit area on the film map -> Relative Distortion map. 40 um 20um in delta position space

  9. Some Samples

  10. Some Samples

  11. Some Samples

  12. Some Samples

  13. Some Samples

  14. Estimation of successful area • Continuity check is suitable which beta-ray alignment is success or not because distortion should be continual. • Check the difference of vector between adjacent area. • For example, • d(dX)(a,b)=dXb-dXa • - if d(dX) < 10umfor >=2 adjacent areas, “a” is defined as continual(successful). b c e a d

  15. beta-ray alignment summary

  16. Continual area ratio of CSDs sucessful sucessful

  17. The reason of below 90% • Not enough beta-rays to align. ---- 1 • Peak is detected, but double. ---- 5 • Large Gap exists. ---- 1

  18. Examples , Double Peak

  19. Examples , Double Peak

  20. Examples , Double Peak

  21. Examples , Double Peak

  22. Examples , Large Gap is Detected.

  23. Examples , Large Gap is Detected.

  24. Examples , Large Gap is Detected.

  25. Summary • Beta-ray alignment was applied to real OPERA Experiment. • The number of beta-ray for alignment is enough. • We estimated mechanical tightness. 26/32 CSDs is aligned successfully. 5/32 CSDs have Double Peaks, these are recoverable by detection both (We have 2 alignments, BG Doublet tracks become twice). 1/32 CSD has large (more than 100um) gap, we can detect it. • We continue the study of these 6 events.

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