Cascade Interactions Research Articles

Monte Carlo event generator MCMHA for high energy hadron-nucleus collisions and intranuclear cascade interactions

The Monte Carlo event generator for high energy hadron-nucleus (h-A) collisions has been developed, which is based on the multi-chain model. The concept of formation zone and the cascade interactions of secondary particles are properly taken account into this Monte Carlo code. Comparing the results of this code with experimental data, the importance of intranuclear cascade interactions becomes very clear.

Electron-phonon interactions in energetic displacement cascades.

The role of electron-phonon interactions in energetic displacement cascades in metals is evaluated by considering the diffusion of electrons in a localized heat spike. It is found that the electronic system in this region always falls out of equilibrium with the lattice at long times and that whether electronic equilibrium is achieved at short times depends almost catastrophically on the parameters that describe the electron-phonon interaction. Neglect of the electron-phonon coupling may lead to overestimates of thermal spike temperatures in many metals.

Irradiation creep models — an overview

The modelling of irradiation creep is now highly developed but many of the basic processes underlying the models are poorly understood. A brief introduction is given to the theory of cascade interactions, point defect clustering and dislocation climb. The range of simple irradiation creep models is reviewed including: preferred nucleation of interstitial loops; preferred absorption of point defects by dislocations favourably orientated to an applied stress; various climb-enhanced glide and recovery mechanisms, and creep driven by internal stresses produced by irradiation growth. A range of special topics is discussed including: cascade effects; creep transients; structural and induced anisotropy; and the effect of impurities. The interplay between swelling and growth with thermal and irradiation creep is emphasized. A discussion is given on how irradiation creep theory should best be developed to assist the interpretation of irradiation creep observations and the requirements of reactor designers.

The Role of Eigensolutions in Nonlinear Inverse Cavity-Flow Theory

The method of Levi Civita is applied to an isolated fully cavitating body at zero cavitation number and adapted to the solution of the inverse problem in which one prescribes the pressure distribution on the wetted surface and then calculates the shape. The novel feature of this work is the finding that the exact theory admits the existence of a “point drag” function or eigensolution. While this fact is of no particular importance in the classical direct problem, we already know from the linearized theory that the eigensolution plays an important role. In the present discussion, the basic properties of the exact “point-drag” solution are explored under the simplest of conditions. In this way, complications which arise from non-zero cavitation numbers, free surface effects, or cascade interactions are avoided. The effects of this simple eigensolution on hydrodynamic forces and cavity shape are discussed. Finally, we give a tentative example of how this eigensolution might be used in the design process.

Interaction Mechanisms Between Tip Leakage Flow and the Passage Vortex in a Linear Turbine Rotor Cascade

In order to study the loss generation mechanisms due to the tip-leakage flow in turbine rotor passages, extensive traverse measurements were made of the three-dimensional flows in a low-speed linear cascade for various tip-clearance sizes and for various cascade inlet flow angles (or incidences). Effects of the leakage flow on the cascade downstream flow fields and interactions between the leakage flow and the passage vortices are discussed in detail based on the traverse measurements and flow-visualization tests in terms of secondary flows and the associated losses. Other traverses were also performed of the tip-casing endwall flows both inside and outside the tip-clearance gap using a micro five-hole pitot tube to reveal the axial development of the interaction throughout the cascade passage. Overall loss characteristics of the present high-turning cascade with blunt leading and trailing edges are obtained and compared with those predicted by the Ainley–Mathieson method.

Increase of the Number of Wounded Nucleons Due to Energy and Baryon Stoppings in Nucleus-Nucleus Collisions

We find in JACEE-3 data a distinctive energy dependence of the excess of non-spector nucleons over those predicted by the Glauber formula on heavy ion collisions. This suggests that energy and baryon stoppings begin to take place and that the cascade interactions within colliding nuclei are important in such low energy regions as JACEE-3 experiments. Then, we need to have a complete Monte Carlo event generator for the analysis of the forthcoming BNL data.

Cascade interactions of high-energy particles with nuclei

Several tens of thousands of internuclear cascades have been computed at energies up 5 to 30 GeV and the results are given. Comparison with experiment shows that the cascade mechanism of interaction of fast particles with nuclei is predominant at these energies.

Cascade interactions of nuclei with high-energy particles

Cascade interactions of nuclei with high-energy particles