Research on the layout of primary control network and new measurement method for the HIAF survey and alignment

Abstract

HIAF (High Intensity heavy ion Accelerator Facility) is one of the major national science and technology infrastructure projects in the “12th Five-Year Plan” undertaken by the Institute of Modern Physics, CAS. The primary control network, as the basic framework of the local coordinate system control of the particle accelerator, is the basis for calculating the coordinates in the process of accelerator construction and implementation, and plays a very important role in the survey and alignment during the construction period and the maintenance and monitoring during the operation period. Based on the multi-dissimilar design structure of HIAF and the unique geological conditions of the construction area, a new high-density layout method of the primary control network and a high-precision 3D(three-dimensional) measurement method were studied, and were successfully applied to the survey and alignment of HIAF. Inside and outside the accelerator tunnel, a high-density 3D primary control network that can form a full envelope for the accelerator beam is respectively laid out. All primary control networks are embedded in the bedrock layer with stainless steel reference inner cylinder and outer protective cylinder, and special waterproof filling layer is set up. All primary control network points in the accelerator tunnel are equipped with measuring intervisible holes and measurement platforms that can directly perform 3D measurements on the ground. By setting up the laser tracker on the horizontal attitude of the measurement platform, the 3D coordinates of the primary control network points inside and outside the accelerator tunnel can be measured directly and with high precision, and the simultaneous adjustment of the measurement data can be completed. The HIAF primary control network layout and measurement method proposed in this paper overcomes the problems of heavy pile foundation, poor crack resistance and poor water seepage resistance of the primary control network laid by the traditional method and solves the problem that the traditional primary control network must separate the plane network and the elevation network for independent measurement. The traditional method of tunnel point and forced centering measurement is avoided. By using a laser tracker to directly measure the 3D coordinates of the primary control network points inside and outside the tunnel, the measurement efficiency and measurement accuracy of the primary control network are improved, and the reliability of primary control network measurements is increased. The feasibility and correctness of the HIAF primary control network layout and measurement method are verified by comparing the actual multi-system measurement results in the field. This method has a certain reference value for the layout of the primary control network of the same type of accelerator.