Determination of the anode wire position by visible light in a new type straw for NA62 experiment tracker

Microscope investigations of new-type thin-wall tubes (straws) produced for NA62 drift chambers revealed that they are semitransparent and allow anode wires to be observed under illumination by visible light. In this work it is shown that positions of wires in straws and thus the anode spacing in the drift chambers can be directly determined with a high accuracy (~5–10 µm) using a microscope mounted on a high-precision optical bench. These data are important for decreasing errors during reconstruction of charged particle track coordinates in the drift chambers. The proposed technique is much simpler than the X-ray or radioactive source methods.