Construction and Testing of a Portable Time Projection Chamber for Fast Neutron Detection
The need to closely monitor the flow of nuclear fuel through the entire fuel cycle is an increasingly important component of global security. Closely connected to this monitoring is the need for improved radiation detectors. Gamma ray detectors experienced a boom in development over the last half...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Published: |
Massachusetts Institute of Technology
2022
|
| Online Access: | https://hdl.handle.net/1721.1/139594 https://orcid.org/0000-0003-1522-5491 |
| Summary: | The need to closely monitor the flow of nuclear fuel through the entire fuel cycle is an increasingly important component of global security. Closely connected to this monitoring is the need for improved radiation detectors. Gamma ray detectors experienced a boom in development over the last half century, but neutron detectors have met a higher level of resistance. When monitoring for the potential proliferation of irradiated nuclear fuel, the fast neutron signature from the spontaneous fission of Plutonium-240 offers a window of opportunity for interdicting illicit nuclear material movement. Directly detecting fast neutrons, as opposed to reaction-based detectors that rely on signal moderation, retains the directional information which can be used to offset low intrinsic efficiency for fast neutron detection. There are currently no portable, directional fast neutron detectors built to date.
This work presents an investigation to build a one-person portable Time Projection Chamber (TPC) for the directional detection of a source of spontaneous fission neutrons, capitalizing on the relative motion to build algorithms for rapidly locating the source of neutrons. A triple mesh avalanche setup is studied to understand the limitations for achieving higher single electron gain. In addition to boosting the gain, an imaging system that uses the light amplification by means of a micro-channel plate is also investigated, with a new approach to the data acquisition algorithms.
New algorithms for data analysis were coupled with new techniques for event-by-event data handling. These were tested using data collected with an AmBe fast neutron source and compared to simulated data. Using the measured fast neutron background and estimates of the measurement uncertainties from stationary data runs, simulations involving relative motion between source and detector show promising results for this technology.
With a one-person portable detector, multiple people can carry detectors that are wirelessly linked to each other, building a combined radiation field map and reducing the time to locating a source through a shared probabilistic model. A portable, directional fast neutron detector will aid in International Atomic Energy Agency (IAEA) inspections, portal security monitoring, emergency response teams, and military search operations. |
|---|