MainPage:Nuclear:Summer2018:Juan

Refractive Index

Before the tiles' light yield could be experimentally determined, their refractive indices needed to be verified. Four Japanese tiles were tested, two from Matsushita Electic Works and two from Japan Fine Ceramics Center. The tiles had theoretical refractive indices of 1.03, 1.02. 1.015, and 1.010. The first two were from Matsushita, while the last two were from JFCC.

Methodology

In order to measure the tiles' refractive indices, an optical method was used. Using a SKIL 8201-CL vertical laser, the deviation of the incoming light due to the aerogel could be measured. Using a protractor, the aerogel tiles were lined up at a 45-degree angle to the incident ray such that only the corner refracted the incoming light. A barrier was set up to view the original and refracted rays 14.125 in away from the tile's corner. The distance between the original and refracted rays was then measured on the barrier. The total angle of refraction could then be calculated using these measurements. Using the following equation, θ= γ − (π/2 + α) + sin^−1[sin α sin γ + cos α(sqrt n^2 − sin^2γ)], a mathematical relationship between the total deflection angle, θ, the angle of incidence γ, and a very small angle α that was taken into consideration should the corners of the tile not be exactly 90°. It should be noted that because α is such a small angle, it will have little impact over the results due to the 45° angle of incidence.

Transmittance Measurements

After experimentally determining the refractive indices for the tiles, their transmittance was to be measured.