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Slow Neutron Detectors
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Neutron detection is challenging primarily because neutrons, like photons, do not have an electrical charge, i.e., they are classified as indirectly ionizing radiation. Unlike α and β radiations, neutrons must first interact in a medium to produce directly ionizing reaction products, or at least some other observable effect. Neutron detectors usually rely upon an interaction with the atomic nuclei within the detector medium and most often it is an absorption or scattering interaction. Slow neutron detectors usually incorporate neutron reactive materials with relatively large neutron absorption cross sections in the low energy region below about 1 keV, whereas fast neutron detectors quite often have relatively large scattering cross sections for neutron energies above 500 keV. Because the differences between the detection methods are considerable, this chapter is devoted to slow neutron1 detectors while the next chapter discusses fast neutron detectors.
Growth of ZnO for Neutron Detectors
Published in Zhe Chuan Feng, Handbook of Zinc Oxide and Related Materials, 2012
Eric A. Burgett, Elisa N. Hurwitz, Nolan E. Hertel, Christopher J. Summers, Jeff Nause, Na Lu, Ian T. Ferguson
Neutrons are particularly difficult to detect because, as the name indicates, they are neutral particles. Detecting them requires a material with a large cross section for charged particle production. The lighter atomic (low Z) materials tend to center around a handful of nuclei whose inner spin-orbit coupling is near to either one or a pair of magic numbers. A magic number is a number of nucleons (protons or neutrons) that can be arranged into complete shells within the atomic nucleus [11]. Atomic nuclei with a magic number of nucleons have a higher binding energy and are more stable against nuclear decay. The nuclei traditionally used as neutron targets are H, He, B, Li, Gd, U, In, and Ag. Neutron detection technologies have focused on one of five main categories: gas-filled tubes, solid foil-based detectors, liquid scintillators, inorganic scintillators, and solid-state detectors.
Enhancement of Fast Neutron Detection in Liquid Scintillator Detectors
Published in Nuclear Technology, 2022
Gang Li, Ghaouti Bentoumi, Liqian Li
Neutron reflector has been used to increase neutron flux in areas such as nuclear reactors, accelerator-based neutron sources, nuclear weapons, etc. The reflector has also been incorporated into thermal neutron detector designs; however, it has not been applied to fast neutron detections before. Via experiments and simulations, this paper demonstrates the effect of fast neutron detection enhancement using reflectors. The enhancement in neutron detection by adding a graphite reflector surrounding the detector cell is predicted to be 50%. Care should be taken because the spatial and timing resolution would be degraded due to the extended coverage and extra scattering. This method is suitable for applications in which cost-effective and highly efficient fast neutron detection is desired, for example, in detecting the presence of fissile materials.
A New Era of Nuclear Criticality Experiments: The First 10 Years of Radiation Test Object Operations at NCERC
Published in Nuclear Science and Engineering, 2021
Jesson Hutchinson, John Bounds, Theresa Cutler, Derek Dinwiddie, Joetta Goda, Travis Grove, David Hayes, George McKenzie, Alexander McSpaden, James Miller, William Myers, Ernesto Andres Ordonez Ferrer, Rene Sanchez, Travis Smith, Katrina Stults, Nicholas Thompson, Jessie Walker
Neutron measurements also have multiple objectives. Systems are used to infer the total neutron emission or dose rate from a configuration. Neutron noise analysis methods are also used, which take advantage of the fact that multiple neutrons can be created from a single fission event at the same time.49,50 Neutron noise methods are performed to infer the system multiplication and/or effective multiplication factor . Neutron imaging is an objective for some measurements. Neutron detector systems generally include proportional counters or scintillators. One system that estimates the neutron emission rate is the Shielded Neutron Assay Probe (SNAP) detector shown in Fig. 4. One example of a He system that is often used for neutron noise measurements is the MC-15 detector (sometimes referred to as the NoMAD detector),14 shown in Fig. 5. An example of an OS system used for neutron noise measurements is shown in Fig. 6.
Development of a water Cherenkov neutron detector for the active rotation method and demonstration of nuclear material detection
Published in Journal of Nuclear Science and Technology, 2023
Kosuke Tanabe, Masao Komeda, Yosuke Toh, Yasunori Kitamura, Tsuyoshi Misawa, Ken’ichi Tsuchiya, Norimitsu Akiba, Hidetoshi Kakuda, Kazunari Shibasaki, Hiroshi Sagara
For neutron detection, sensitivity to gamma-rays is an obstacle. When gamma-rays above 0.423 MeV enter the detector, Cherenkov photons are generated by the same process as neutrons, and the number of Cherenkov photons increases with increasing energy of incident gamma-rays. Therefore, discrimination between neutrons and gamma-rays is essential to detect only neutrons using the WCND. In this study, gamma-rays are planned to be suppressed at a trigger level by setting a threshold value for the photon yield of the WCND. The addition of Gd is intended to increase the neutron sensitivity as well as the neutron-induced photon yield. The discrimination method using differences in the photon yield is henceforth referred to as pulse height discrimination.