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In nuclear physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. The neutron cross section σ can be defined as the area in cm 2 for which the number of neutron-nuclei reactions taking place is equal to the product of the number of incident neutrons that would pass through the area and the number of ...
Devices coated with natural Gd have also been explored, mainly because of its large thermal neutron microscopic cross section of 49,000 barns. [37] [38] However, the Gd(n,γ) reaction products of interest are mainly low energy conversion electrons, mostly grouped around 70 keV. Consequently, discrimination between neutron induced events and ...
Monte Carlo N-Particle Transport (MCNP) [2] is a general-purpose, continuous-energy, generalized-geometry, time-dependent, Monte Carlo radiation transport code designed to track many particle types over broad ranges of energies and is developed by Los Alamos National Laboratory.
The chance is dependent on the nuclide as well as neutron energy. For low and medium-energy neutrons, the neutron capture cross sections for fission (σ F), the cross section for neutron capture with emission of a gamma ray (σ γ), and the percentage of non-fissions are in the table at right. Fertile nuclides in nuclear fuels include:
Merlin is a neutron spectrometer with a high-count-rate, medium-energy-resolution, direct-geometry chopper spectrometer. Osiris can be used as a neutron spectrometer or diffractometer. It is optimised for very low-energy studies and long-wavelength diffraction. Pearl is a neutron diffractometer dedicated to high-pressure powder diffraction.
The predecessor group to the NNDC was founded in 1951 when a group known as the Brookhaven Neutron Cross Section Compilation Group was formed at the Brookhaven National Laboratory. In 1955 this group published the reference book "BNL-325," which had to do with the cross-sections of neutrons. After being renamed the Sigma Center, the group was ...
The cross section obtained in this way is called the total cross section and is usually denoted by a σ or σ T. Typical nuclear radii are of the order 10 −15 m. Assuming spherical shape, we therefore expect the cross sections for nuclear reactions to be of the order of π r 2 {\displaystyle \pi r^{2}} or 10 −28 m 2 (i.e., 1 barn).
Se-79, half-life of 327k years, is one of the long-lived fission products.Given the stability of its next lighter and heavier isotopes and the high cross section those isotopes exhibit for various neutron reactions, it is likely that the relatively low yield is due to Se-79 being destroyed in the reactor to an appreciable extent.