Neutronbeskyttelse

Neutronbeskyttelse refers to the shielding or protection against neutrons, which are neutral subatomic particles found in atomic nuclei. Neutrons are particularly challenging to shield because they lack an electric charge, meaning they do not interact with matter via electromagnetic forces as charged particles like electrons or protons do. Instead, neutrons interact primarily through nuclear forces, often leading to nuclear reactions that can produce secondary radiation, such as gamma rays or other neutrons.

Effective neutron shielding typically involves materials rich in hydrogen, as hydrogen nuclei (protons) have a similar mass to neutrons, allowing for efficient energy transfer and slowing down of the neutrons through elastic scattering. Water, polyethylene, and paraffin are common hydrogenous materials used for this purpose. As neutrons are slowed down (thermalized), they become more susceptible to capture by certain atomic nuclei. Materials like boron or cadmium are often incorporated into neutron shielding to absorb these thermalized neutrons. Boron-10, for instance, has a high cross-section for absorbing thermal neutrons, converting them into alpha particles and lithium nuclei.

Beyond hydrogenous materials and neutron absorbers, the secondary radiation produced by neutron interactions also needs to be considered. Gamma rays, often emitted during neutron capture, require dense materials like lead or concrete for attenuation. Therefore, a comprehensive neutron shielding strategy often involves a combination of materials designed to first slow down the neutrons and then absorb them, while also accounting for any accompanying gamma radiation. The thickness and composition of the shielding depend on the neutron energy spectrum, the intensity of the neutron source, and the desired level of protection. Applications for neutron shielding include nuclear reactors, particle accelerators, and neutron radiography facilities.