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Fast Neutron Detectors
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
In this chapter many different types of fast neutron detectors have been briefly described. The detection of fast neutrons is accomplished by using one of the following three techniques. (1) The fast neutrons are first moderated to lower energies and those that become thermalized are detected using thermal neutron detectors. Bonner spheres and rem balls are examples of fast neutron detectors based on the moderation principle. (2) Charged recoil atoms produced by fast neutron scattering can be measured in charged particle detectors. This technique is the basis for many types of recoil spectrometers. (3) Finally, fast neutrons can often produce nuclear reactions not possible with thermal neutrons and products of these fast neutron interactions can often be measured and the fast neutron flux can be inferred. Foil activation methods typify the use of this method to distinguish neutrons with a wide range of energies.
Space Dosimetry
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Jarvis A. Caffrey, David M. Hamby
Bonner sphere detectors provide a method for determining neutron energy spectra by surrounding a 3He proportional counter with polyethylene spheres of varying thickness. 3He proportional counters respond well to neutrons across a broad range of energy by way of the 3He (n,p) 3H reaction. Each moderating sphere yields a unique spectral response as energetic neutrons are moderated to varying degrees.
An Optimized Method for Bonner Sphere Spectrometer Design and Validation by Measuring 252Cf Spectra
Published in Nuclear Technology, 2021
Qingjun Zhu, Xianfang Meng, Wuhui Chen, Songlin Liu, Kai Huang
The neutron spectra measurement technique plays a key role in nuclear instrument technologies as it can offer crucial information for nuclear analysis,1 radiation shielding design,2 and other industrial applications of neutron techniques.3 As a widely used neutron spectrometer, a Bonner sphere spectrometer determines neutron spectra indirectly.4 It comprises of a set of concentric moderating spheres of different diameters, and each sphere has a thermal neutron detector located in the center. Thus, the response of each sphere to monoenergetic neutrons is different. The neutron spectrum is the solution of Eq. (1):