Compact Readout for an Intelligent Segmented Autonomous Neutron Directional Detector

Project Overview

Shielded special nuclear material (SNM) is very difficult to detect. Gamma-ray signatures can be shielded by relatively modest amounts of shielding. Fast neutrons are much more penetrating and can pass through a relatively large mass of shielding without interacting. Furthermore, fast neutrons provide a clear and unambiguous signature of the presence of SNM with few competing natural sources. With the capability to image the source it is possible to narrow down the nature of the signal even further. With the recent developments of pulse-shape-sensitive plastic scintillator, silicon photomultipliers (SiPM), and highly scalable and fast Positron-Emission-Tomography (PET) multi-channel readout systems, we believe the development of a field deployable neutron imager is now within reach. What is needed is an evaluation of both the pulse shape sensitivity of such PET readouts and their excellent timing characteristics. This Feasibility Study comprises a test of the Time-of-Flight (ToF), Pulse-Shape Discrimination (PSD), and neutron imaging capabilities of PET-scanner readout electronics. It has been shown that while PSD is achievable for a detector constructed of Stilbene crystals, PSD plastic showed only limited PSD, indicating further improvement is required on the readout side. The timing and energy resolution of such systems appear to be adequate for neutron imaging in a compact fully-segmented plastic-scintillator detector.

Preliminary sensitivity to neutron directions has been observed in this project, which makes this approach feasible to make compact neutron imagers based on LLNL PSD-capable plastic scintillator and low-power feature-extraction multi-channel readouts. Further work to improve these results has been outlined.

Mission Impact

There is a need for compact neutron imaging capability that can be deployed in the field. Such a detector can be used to detect shielded SNM in environments such as border crossings, or ports of entry. However, such a detector has not been realized primarily because the electronics required to make it work is too bulky and cumbersome. This project was formulated to assess the practicality of new forms of miniaturized electronics solutions which have come on to the market for PET applications.

Publications, Presentations, and Patents

Li, Viacheslav, "Intelligent Detection of Nuclear Threats." Virtual Presentation, Bay-Area National-Lab Accelerator Pitch Event. Sep 9, 2021.

Li, Viacheslav, "Advances in radiation detectors based on finely-segmented PSD plastic scintillator: from fast neutrons to reactor antineutrinos." Virtual Presentation, International Conference on Technology and Instrumentation in Particle Physics (TIPP). May 24-28, 2021.

Li, Viacheslav, "Advances in radiation detectors based on finely-segmented PSD plastic scintillator: from fast neutrons to reactor antineutrinos." Virtual Presentation, APS April, 2021.

Li, Viacheslav, "Towards scalable fast-neutron and reactor-antineutrino detectors based on 6Li-doped PSD plastic scintillators and SiPM arrays." Virtual Presentation, CPAD Instrumentation Frontier Workshop, March 18-22, 2021.

Li, Viacheslav, "SANDD, or towards modular compact fast-neutron and reactor-antineutrino detectors based on 6Li-doped PSD plastic scintillator and SiPM arrays." Virtual invited talk, University of Hawai`i, Physics Department Colloquium, March 11, 2021.

Li, Viacheslav, "Developing intelligent Segmented Autonomous Neutron Directional Detection (iSANDD) systems." LLNL NACS Ideas Day, Livermore CA, February 9, 2020.

Wu Tingsiuan, "Obtaining directionality information from scatter-capture fast neutron detectors." PhD prospectus talk, University of Michigan. May 6 2021.

Wu, Tingshuian,"Obtaining directionality information from scatter-capture fast neutron detectors."University Program Review Meeting, Sep 8-10, 2021.