Investigating the functionality of a data acquisition system of a proton precession magnetometer

This experiment investigated an improved data acquisition system and its functionality to a proton precession magnetometer which has been previously developed at the Department of Physics, University of Colombo[1]. The proton precession magnetometer which is used to measure the geomagnetic field, can be recognized as a scalar magnetometer based on the concept of the nuclear magnetic resonance. The data acquisition system was introduced to improve the frequency measurement of the magnetometer which consisted of a magnetic sensor in dual solenoid configuration, and water as the proton rich material, and an instrumentation amplifier (AD8221). A PCM1808 module was introduced as an ADC to digitize the proton precession signal and transferred into an ESP32 module to store the data in a memory chip. Then the proton signal's frequency was determined with the aid of fast Fourier transform using Octave software. In order to examine the capability of the setup, the variations of the geomagnetic field were observed in a location in Kottawa, Sri Lanka and the mean geomagnetic field was determined with an accuracy of 0.12%.