Resonance Effects in Nuclear Processes

Abstract

A general formula is developed for the probability of nuclear processes with particular consideration of resonance ()2). The dependence of the cross section on the energy of the incident particle can be divided into two parts: Firstly, the dependence over energy regions small compared to nuclear energies, and secondly that over large energy regions, of the order of a million volts or more. The first dependence is completely given by the resonance formula; 'The width would be smaller for charged particles of "medium" energy, i.e. , such energy that the penetrability of the Coulomb potential barrier is small compared to unity but still large enough to make the disintegration observable. We shall come back to this case in $10.

Remote determination of sample temperature by neutron resonance spectroscopy

“…In the simplest case, for a monatomic free gas or classical solid, by taking a Maxwellian distribution of velocities for the target nuclei corresponding to a temperature, T, the energy transfer function becomes [6,7] …”

“…It was realised by Bethe in the late 1930s that individual neutron absorption resonances exhibit a broadening with increasing temperature, as a result of the Doppler effect from the thermal motion of the target nuclei as viewed in the laboratory frame [6,7]. However, it was not until the 1950s that it became possible to perform studies of absorption resonances with sufficient resolution to directly measure the Doppler broadening [8].…”

Monte Carlo analysis of reactivity coefficients in fast reactors general theory and applications

“…The uranium oxide rod contained depleted uranium, combined stoichiometrically with oxygen and sintered to 70% of theoretical density. The vacuum jacket, heater wires, and support structure filled the surrounding space with iron, nickel, and chromium with atomic densities, respectively, of 0.0127, 0.0018, and 0.0046 (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) mixture. The Doppler sample is located The theoretical method developed by combining these theories into a consistent algorithm was used as the basis for the AMC digital-computer program.…”

Simulation for neutron resonance absorption spectroscopic tomography

“…By analyzing energy, intensity and Doppler broadening of each resonance absorption peak, we can identify individual nuclides, deduce its density and study its dynamics. Hence, neutron resonance absorption spectroscopy (N-RAS) is a unique method in terms of the nuclideselective measurement of dynamics as effective temperature that corresponds to the average energy per vibrational degree of freedom of the lattice, including zero-point energy [1,2]. Therefore, N-RAS was applied in the field of material sciences such as ionic conductors [3] or layer compounds [4].…”