Every single type of neutron detector contains a conventional radiation detector in combination with the converter. Therefore, you should know that the detection of neutrons is highly specific because we are talking about electronically neutral particles.
They are highly subjected to significant nuclear forces, but they do not feature electric forces, as we have mentioned above. We can say that they are not directly ionizing, which means that we have to convert them into changed particles before the detection.
Thermal Neutrons Detection
We can differentiate thermal neutrons that are working within the thermal equilibrium and they feature an average temperature of 290K. Have in mind that this particular aspect of neutron’s energy spectrum is highly important especially for thermal reactors in general.
The thermal ones come with larger and different neutron absorption through radioactive capture or fission, especially when compared with fast neutrons. We can differentiate numerous detection methods as well as detectors.
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If you are using nuclear reactors, the most common detection method is gaseous ionization since it will cover a wide range of neutron flux, and it is both reliable and efficient along the way.
Different types of gaseous ionization detectors are part of the NIS or nuclear instrumentation system, which monitors the power of the reactor and detects neutron leakage from the core.
Remember that ionization chambers are commonly used for detecting charged particles. Therefore, if the inner surface features a thin layer of boron, that will lead to a reaction that will provide you with essential data.
Most reactions within thermal happen in combination with gamma emissions. At the same time, the coat features isotope boron-10 that comprises high reaction within the energy spectrum.
The alpha particles inside the chambers will create ionization, and that will eject electrons through the secondary ionization process.
We can also use gas boron trifluoride to detect them by using the ionization chamber instead of air. Since neutrons will produce alpha particles, they will generally react with the detector gas and boron atoms.
Both methods will provide you the possibility to detect them within the nuclear reaction, but you should have in mind that they operate by using proportional region.
It is important to understand that fission chambers are generally ionization detectors that are commonly used to detect neutrons. You can use it also to monitor neutron flux or reactor power by using the intermediate flux levels.
They will also provide you reactor trip signals, alarms and other indications that will serve you as a convenient solution. The design will provide you overlap between full span of power range instruments and source range channels.
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When it comes to fission chambers, you should know that they feature a thin layer or uranium-235 that has the ability to detect them. Since they are not directly affected by ionization, the chamber has to convert them before detection.
For instance, thermal neutrons can cause fission of atoms of uranium-235, which means that two fragments will produce large kinetic energy and lead to ionization of argon gas, which is within the detector.
The main benefit of using uranium-235 coating instead of boron-10 is because fission fragments feature more significant energy than alpha particles that happen after boron reaction.
As a result, the fission chamber is much sensitive to neutrons, and that will allow you to operate in high gamma fields when compared with boron lining.
Flux Wires and Activation Foils
We can also detect neutrons by using flux wires and activation foils. This particular method requires neutron activation, which means that they will irradiate analyzed samples with neutrons with an idea to produce particular radionuclides.
The radioactive decay is specific for each element, and it emits the characteristics similar to gamma rays that we can measure by using gamma spectroscopy. The most common materials used for activation foils include iron, rhodium, indium, gold, niobium, and aluminum.
These elements are vital for the capture of neutrons, so we can easily determine the number of neutrons that the foils were exposed. You should find a professional Neutron Detectors manufacturer that will provide you with this particular solution.
At the same time, flux wires have general use in nuclear reactors to measure neutron flux profiles, and the principles are the same. You just have to insert foil or wire into the reactor core for the time required for it to reach the level you want.
As soon as it activates, you should rapidly remove it from the reactor core and count the activity. You can place a cover over it to filter out certain energy levels, which means that you can add cadmium to absorb thermal neutrons.