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TY - CPAPER AU - Eremeev, G.V. AU - Iriks, D.C. TI - Automatic Surface Defect Detection and Sizing for Superconducting Radio Frequency Cavity Using Haar Cascades J2 - Proc. of International Conference on RF Superconductivity (SRF2015), Whistler, BC, Canada, Sept. 13-18, 2015 AB - Serious albeit tiny surface defects can remain on the surface of superconducting radio frequency (SRF) cavities after polishing and cleaning. These defects reduce the efficiency of cavities and often limit the maximum attainable fields. We applied a Haar cascade artificial vision technique for automated identification, counting, and sizing of defects induced on niobium surface by Nb-H precipitates formed at cryogenic temperatures. The defects were counted and sized by a computer program and also counted and measured manually to estimate detection rate and accuracy of sizing. The overall detection rate was 53%, and the overall false positive rate was 29%. The technique that was used to automatically size the features was found to oversize the features, but oversize them consistently, resulting in a size histogram that represents the defect size distribution on the sample. After scaling the histogram data, the average defect area was found to be 90 square micrometers with the standard deviation of 70 square micrometers. PB - JACoW CY - Geneva, Switzerland SP - 788 EP - 790 KW - cavity KW - niobium KW - background KW - radio-frequency KW - SRF DA - 2015/12 PY - 2015 SN - 978-3-95450-178-6 DO - 10.18429/JACoW-SRF2015-TUPB082 UR - http://srf2015.vrws.de/papers/tupb082.pdf ER -