Bent crystal characterization from autocollimator measurements

Established in 2010, the UA9 Collaboration primarily studies the interactions of high-energy particles with bent silicon crystals using a specialized apparatus on the H8 beam line at CERN-SPS North Area. Crystals of various shapes are studied using high-energy beams of hadrons or leptons for purposes like crystal collimation, beam extraction, reducing hardware irradiation, and importantly, beam merging. The usual crystals are either tiny strips or rectangular slabs, bent along a main axis to create an orthogonal anticlastic response. We introduce an optical technique utilizing autocollimators to accurately determine the two crystal curvatures with an unmatched level of precision. Applying it to crystals addresses the challenge of rapid crystal curvature measurement in the lab, eliminating the trial and error method based on particle irradiation to significantly decrease the required beam time. Comparisons of the optical measurements with beam-based assessments demonstrate a significant similarity between the methods.