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Original Authors: Kevin Develle, European Organization for Nuclear Research (CERN)
Edited by Cyth Systems
We at CERN needed a system to monitor both natural ground motion and industrial vibration with tight timing restrictions. The system required persona-based access to data to share with CERN databases and international seismic databases.
We created a system based on the cRIO-9035 controller, two NI-9239 C Series modules, broadband seismometers, and high-definition motion sensors. We used the embedded FPGA in the LabVIEW Real-Time application to communicate through miniSEED with the CERN infrastructure.
Ground Vibration Acquisition System
Here at CERN, we developed a custom solution that encompasses measuring both natural ground motion (using a broadband seismometer) and industrial vibration in real-time using NI CompactRIO hardware. We required deterministic, high-speed inputs that were to be easily implemented with Large Hadron Collider (LHC) tunnel and were robust in harsh environments. Also, we required the data acquisition system to communicate with the CERN infrastructure so that we could easily analyze the data and store it to our LHC database.
We chose the cRIO-9035 controller with two NI-9239 C Series modules to meet these different requirements. We developed a LabVIEW Real-Time application to make use of the embedded FPGA.
The cRIO’s system enabled us to acquire, process, and share raw data in real time. The system functions by sending raw data to SED, which redirects it toward the worldwide seismic databases. CERN scientists can access all measured data. All of the data is post-processed independently to fulfill the requirements of the users. If one of the hardware modules fails, the system is able to continue streaming data through resource reallocation.
One of the challenges with this application was achieving the time accuracy required (1 ms). Like any seismic data logger, we needed external synchronization. An NTP service at CERN provides a time accuracy below 1 ms and does not require external hardware, we chose this reference to develop CERN seismic stations.
Left: Seismometer locations (Switzerland), Right: Recorded Earthquake Close to Chamonix.
We designed the network for compatibility with the LHC harsh environment and to track the ground motions between 30 s and 100 Hz, with amplitudes ranging from LHC ground motion up to 2 g. This wide measurement range helps us get accurate feedback on the ground stability in LHC tunnels.
The data, made available at CERN and for seismic organizations worldwide, can be used for very diverse applications. The study of the impact of earthquakes on the LHC can guide the GEothermie 2020 project, which aims to develop the use of geothermal energy in the Canton of Geneva without impacting CERN experiments. Scientists plan to use the data in the HL-LHC framework project to upgrade the LHC. Vibration levels will be of particular interest during the excavation of the new shafts. Finally, the network will be used as a valuable reference for monitoring vibration levels in the LHC on a long-term basis.
The systems have run 24/7 for several months and are fulfilling all requirements.
Kevin Develle, European Organization for Nuclear Research (CERN)
Edited by Cyth Systems