Direct measurement on stretched wire to constrain the longitudinal network in CSNS

Abstract

The elongated and non-closed structure of the longitudinal control network can lead to the accumulation of measurement errors from station to station, causing distortion and preventing the attainment of high-precision longitudinal control network coordinates. This fails to meet the high-precision alignment requirements of the accelerator components. In this study, the absolute scanner AS1 and Leica AT960 laser tracker were used to directly measure the 180-m long stretched wire in the CSNS LINAC tunnel and obtain its three-dimensional coordinates. The obtained data was used to constrain the transverse of the longitudinal control network, effectively improving its accuracy. The Helmert variance component estimation method was incorporated into the data adjustment algorithm, which reasonably allocated weights between horizontal distance, azimuth angle and offset. As a result, the transverse accuracy of the control network improved from 0.151 mm without wire constraint to 0.086 mm with wire constraint. In the future, we plan to apply this method to connect the control network on both sides of the lengthy sight-hole in CSNS-II.