Magnetic saturation: educated guessing

In finite-element solutions at low magnetic fields, the properties of ferromagnetic materials are not critically important. The quantity used in the solutions is γ= 1/μr. In this case, both 1/800 and 1/8000 are close to zero compared to unity; therefore, the details of the μr(B) curve make little difference in the solution. On the other hand, […]

Modeling radioactive sources with GamBet

Many processes represented by GamBet, such as the emission of bremsstrahlung photons and Compton electrons, involve interactions with atomic electrons. Particle emission may also follow from reactions within nucleii. Although GamBet does not address nuclear physics, the program can determine the histories of particles created by nuclear events. There are two types of processes: nuclear reactions […]

Particle transport C: Monte Carlo methods versus moment equations

This is the concluding of three articles introducing the basic concepts of the Monte Carlo method for radiation transport calculations. The demonstration calculations discussed in the previous articles give a basis for comparing the relative benefits and drawbacks of the Monte Carlo and transport equation approaches. We have seen that both strategies are based on averages […]

Particle transport B: Monte Carlo methods versus moment equations

This is the second of three articles introducing the basic concepts of the Monte Carlo method for radiation transport calculations. In this article, we’ll consider an alternative to the Monte Carlo treatment of the two-dimensional random walk: the derivation and solution of a transport equation. Here, we define an appropriate quantity averaged over a random distribution […]

Particle transport A: Monte Carlo methods versus moment equations

This is the first of three articles giving a brief introduction to Monte Carlo methods applied to electron/photon transport, the foundation of our GamBet package for X-ray science. In particular, I will use a simple example to show how Monte Carlo compares to transport equations (e.g., the diffusion equation). The fundamental issue is how to deal […]