Binp Capacitive and Ultrasonic Hydrostatic Level Sensors

Slow ground motion study for future accelerator projects and alignment of large accelerator machine components with high accuracy are important tasks now. One of the prevalent tool for solution of these tasks are Hydrostatic Level Sensors designed to work into the Hydrostatic Levelling System, which is based on principle of communicating vessels. All water level measuring sensors are linked to its neighbours by a system of tubes. So the principle is based on the equilibrium of the pressure of liquid in communicating vessels. Since 2001 year BINP took part in development and fabrication of Hydrostatic Level Sensors in the network of team-work with FNAL and SLAC. At the beginning BINP developed capacitive HLS sensors and then in 2005 ultrasonic HLS sensors. Last year in accordance with the program of collaboration between BINP and SLAC high-resolution capacitive (SASE) and ultrasonic (ULSE) hydrostatic level sensors for the Linac Coherent Light Source (LCLS) Undulator Alignment System were developed and fabricated. The LCLS is the SLAC program aimed at the development of a coherent X-ray source. The capacitive sensors will be used at LCLS in combination with ultrasonic sensors, in order to provide accurate measurement of alignment with possibility of absolute calibration of the sensors. On each girder of the Undulator it will be installed one ultrasonic sensor and three capacitive sensors. The detailed view of the sensor’s installation is presented on Fig. 1. The sensor of number 1 is of ULSE type, the other sensors (number 2 to 4) are of SASE type.