| The Jiangmen Underground Neutrino Observatory(JUNO)project is a large-scale experiment to further study neutrino after the Daya Bay neutrino experiment.The project needs to build a large neutrino experimental station containing two parts: water and underwater.Through the core components of "detector" to measure the reactor neutrino energy spectrum accurately so as to measure the quality order of neutrino.Besides,it also measure the oscillation parameters,of neutrinos and supernova neutrino etc.In order to ensure the safety of the experimental process and the accuracy of the experimental results,the experiment has very strict environmental requirements.So,it is significance to carry out the research on the design and realization of the monitoring system for the key parameters of the neutrino experimental environment.The key environmental parameters of the upper part of water include temperature,humidity and pressure.There are several laboratories on the upper part of water and many points in each laboratory need to be monitored.Considering of the above requirements,an upper part of water monitoring system that based on STM32 and raspberry pi is designed.The system includes the environment data acquisition module with STM32 as the core and a primary monitoring unit with the raspberry pi as the core.The acquisition module collects the temperature,humidity and pressure parameters of each monitoring point in the laboratory,and then transmits these parameters to the main monitoring unit in the monitoring area by wireless way.The main monitoring unit receives the data by wireless way and realizes the sorting,storage and display.Besides,it also has the Internet communication interface.The key parameters of the underwater part of the experimental station are the temperature of the pure water around the detector.The detector is installed in a large pool.The water temperature will affect the performance of the detector,so the water temperature at different points around the detector needs to be monitored in real time.Considering the above requirements,a pure water temperature monitoring system is designed based on Fiber Bragg Grating(FBG)temperature sensor and FBG demodulator.The system includes a FBG temperature sensor,a FBG demodulator and a main monitoring unit.The sensors at differentmonitoring points are connected through the optical fiber and one end is connected to the channel interface of the demodulator.The demodulator detects the central wavelength of each sensor and transmits the data to the corresponding main monitoring unit through the network cable.The main monitoring unit converts the central wavelength into the water temperature data of the monitoring points through the data processing.If there is a breakpoint in the series connected sensor group,the reliability of the monitoring system can be ensured.The monitoring system is provided with a disaster recovery function a by connecting the two ends of the optical fiber to the channel interface of the demodulator.The prototype of the monitoring system has been run and tested in the laboratory for a long time and has been tested at the South China National Measurement and Test Center..The experimental data shows that the acquisition module temperature error is less than 0.5℃,the humidity error is less than 3%RH,the pressure error is less than 1mbar,and the pure water temperature error is less than 0.2℃.The errors meet the requirements of the JUNO project completely. |
