As each photon is generated it is initially given an isotropic orientation. From there it is tracked until it is absorbed by the liquid, absorbed by the cell wall or until it enters the fiber core. Transmission across the liquid-fiber interface is handled as a lossless cass of Snell's law (with total internal reflection if applicable). At the outer cell the walls the photon can be absorbed or reflected. If reflected, the new direction can be either specular (mirror-like) or diffuse. The diffuse model is currently quite unphysical; it uniformly distributes the direction vector over the allowed hemisphere. A better model (cf. books on graphics and ray-tracing) would have the distribution peaked towards the specular direction. The admixture of which reflection model to use is set by the user and is independently chosen for each reflection. The end caps of the cells are assumed to be perfectly absorbing (total loss).
The simulation does not currently account for wavelength dependent affects. Thus the interplay between the spectrum of generated photons, reflection coefficients, and absorption spectrum of the fiber are not included.
| cell & fiber length | 800 cm |
| liquid \Lambda_{atten} | 600 cm |
| n_{liquid} | 1.47 |
| ocfrac | 0.01 |
| icfrac | 0.03 |
| n_{outclad} | 1.49 |
| n_{inclad} | 1.49 |
| n_{core} | 1.60 |
Each plot represents a single cell and fiber size. The box and fiber diameter outlines are drawn for scale. The effect of fiber placement is studied by (independently) simulating 5 different displacements for each set of physical sizes.
At each combination a tic-tac-toe hash of numbers is shown. The rows represent different overall reflection rates of: 98%, 95%, 90%. The columns represent different mixtures of specular and diffuse: 100%/0%, 50%/50%, 0%/100%. Each value represents a percentage of photons generated that make it into the fiber core. Note: this does not include the effect of smaller/large initial yields due to different path lengths in scintillating liquid volumes as the sizes change.
