Sensor Calibration Using Americium-Aluminum in the NEWS-G Experiment at SNOLAB

The new experiments with spheres - gas (NEWS-G) experiment is an international collaboration working with spherical gas detectors. The detector works by filling a sphere with a concentrated gas and placing a multi-anode sensor inside the sphere. When a particle interacts with the gas, the gas gets ionized, and an ionization electron is created. When a high voltage is applied to the anodes on the sensor, the ionization electron is attracted to the anodes. Once the electron reaches an anode, it can be detected. Ideally, a light dark matter particle would interact with the gas and be detected. In this experiment, the sensor at NEWS-G in SNOLAB had broken and needed to be replaced. To replace the broken sensor, the experiment required that a new sensor be calibrated to ensure it was working properly. The new sensor was calibrated at Queen's University using an americium-aluminum source which emitted X-rays of known energy levels. By placing the source on different parts of the sphere, each anode can be tested, and the results from each anode can be analyzed. After reviewing all the collected data, it was found that a few of the anodes had gain differences, likely due to the anode not being centered on the wire to which it was connected. All of the anodes detected the source, seeing similar results, and it was determined that the sensor was functional enough to be used in the NEWS-G experiment at SNOLAB.