1. In-Flight Radiation Detector Testing
Zachary Paul, Devon Madden
Faculty Advisor: Dr. Marcus Hohlmann, Dept. of Aerospace, Physics, and Space Sciences,
Florida Institute of Technology
Introduction
While still in its testing phase, the purpose of this detector is to monitor the direction of incoming radiation into the cabin of 15km and higher altitude vehicles as away to know where shielding must be placed to reduce the amount of radiation that can enter. The fundamentals and testing procedures to be discussed use the large Gas Electron Multiplier (GEM) detector as its basis [1].
Figure 1: 10x10cm In-Flight Radiation Detector
Background
Originally a CERN based project for particle physics research, it was realized that the same system and relative design use in the GEM could be used for checking radiation leaks in aircrafts, where higher energy radiation is more present. Detection of particles works through the method of “electron avalanching” (Fig. 2). This method is used to amplify the amount of electrons within the detector to so that the amperage is high enough to be read by the electronics as a signal.
Figure 2: Displays the process of electron avalanching (above) [2]
Figure 3: Diagram of the holes within a foil that the electron passes through to create more electrons [2]
Methods & Testing
Multiple tests must be conducted on the detector to make sure it operates properly, all done in a specific order as each test having certain things be deemed as working properly before the detector can be used for its intended application. These tests are known as Quality Control (QC), used to prevent any damage from occurring and that it operates properly.
The GEM Foil test (QC2) ensures that each individual foil has an impedance of over 100 GΩ, this such a high impedance reduces the chance of shortages on relatively high voltages, and that there are no particulates on the foils. The Gas/Pressure test (QC3) makes sure that there are no leaks within the case as any place the gas can get out is any area oxygen can get in which can cause detection issues. The High Voltage (HV) test (QC4) is conducted to check for the amount of noise within the system that could come across as a radiation signal. The Gain Calibration tests (QC5) includes two parts: the Effective Gain Measurement (EGM) and Response Uniformity test. The purpose of the EGM test is to ensure an amplification of current and electrons from the drift to the readout as well as identify the presence of cosmic events utilizing a radiation source. The Response Uniformity test is conducted to verify that each GEM foil receives approximately the same amount of electrons when HV is applied.
Results & Future Work
Testing of QC5 is on going as issues have risen of a non-damaging discharge pulse must be found and dealt with as it occurs at such a high rate that it looks like a signal itself.
References
[1] Abbas, M., Bianco, M., Gola, M., Merlin, J. A., De Oliveira, R., & Shah, A. (2017). Technical Assembly Manual for GE1/1 Chambers. CERN, Retrieved February 16, 2019.
[2] CERN Gas Detectors Development: Gas Electron Multiplier. (n.d.). Retrieved February 18, 2019.