What Are Neutron Ionization Chambers?

Ionization of gases by neutrons was the name of an early particle seen on neutron detectors. The author was well-aware of the neutral nature of neutrons. In his initial attempt to study neutrons, he and colleagues made the decision to go all the way from a neutron to the resulting signal. To their surprise, they were really able to record something: a current created by neutrons was flowing through the chamber.

The ion chamber was not used as a neutron detector for several years. The cloud chamber, a device that increased in popularity at the cost of the ion chamber's development, provided a wealth of additional neutron-related data. There are many different kinds of detectors that can be turned into neutron detectors by adding a substance that performs a conversion process from the original radiation data to a charged particle. It is possible to identify the primary neutron by using the recoil nucleus in a neutron scattering experiment, the reaction products in a nuclear reaction, or the fractured fission products in a nuclear fission. Tubes were frequently employed as detectors. For neutron detection they were called "neutron counter tubes" or "radiation counter tubes", abbreviated "counters". Neutron chambers are a more generic name. A neutron counter or a neutron spectrometer can be used as the neutron chamber.

Three types of neutron counters will be discussed here: the fission chamber, boron-trifluoride, and the boron-lined neutron chamber. These chambers can be used as spectrometers or counters, depending on the application. Detectors that slow down neutrons use one of the aforementioned chamber types. In this context, a chamber refers to a detector that uses a gas to detect charged particles as the next step in the detecting chain. The ion-chamber, proportionality, corona-discharge, and Geiger-Müller range have all been employed for neutron sensitive ionization chambers in the past. Pulse counting systems and current measurement systems both employ ion chambers. Pulse detection systems use voltage, charge, or current sensitive preamplifiers to detect the electron-ion pair clouds generated in the chamber. For fission chambers, the current-pulse detection approach has lately become popular because of its low noise and high signal-to-noise ratio. While commonly referred to as current detectors, they should not be confused with chamber systems that employ the mean current as an information carrier.