31. What is unique about copper is its long mean free path ( approximately 100 atomic spacings at room temperature ). 32. Except for high quality crystals at low temperatures, the phonon mean free path is not reduced significantly at higher temperatures. 33. Temperature dependence of the mean free path has an exponential form { e } ^ { \ Theta / bT }. 34. The mean free path can be increased by reducing the number of impurities in a crystal or by lowering its temperature. 35. The journey of an electron can be expressed in another way, which is by use of the mean free path . 36. Radiation treatment planning has pencil beam scanning as one of its modalities . mean free path is involved in IMRT planning. 37. When " L " is larger than the phonon mean free path , Umklapp scattering process limits thermal conductivity. 38. Because of spectrum hardening, the " mean free path " of the X-ray spectrum changes with distance. 39. The effect is strongest when the mean free path of the gas molecules is comparable to the dimensions of the gas container. 40. Fast electrons which move at a large fraction of the speed of light have a mean free path up to 100 times longer.
