This quantity is not small relative to the container when the Knudsen number is high.
de Haas and Biermasz found an expression for this quantity for phonons. The dominant spin-flip mechanism in semiconductors is independent of this quantity, while in metals the spin flip length is linearly proportional to this quantity in the Elliot-Yafet mechanism. Precise pressure and temperature conditions are maintained in the apparatus named for Franck and Hertz to control this quantity. In acoustics, this quantity is estimated as four times a container's volume over its surface area. In fission, the radius of a spherical critical mass is equal to the product of this quantity with the square root of one plus the number of scattering events per fission event. This quantity is not small relative to the container when the Knudsen number is high. For 10 points, name this quantity equal to the reciprocal of particle density times effective cross section, a measure of how far a particle will travel, on average, between collisions.
de Haas and Biermasz found an expression for this quantity for phonons.
{mean free path}