Linear Energy Transfer and Neutrons

[Atombob]

It is my understanding that the concept of L.E.T. relates to the ammount of energy deposited in an absorber by a  charged particle (ie..alpha/beta/positron).

Although on page91 of Gollnick 4th ed. LET is used to describe the effect of neutron dose. Last time I checked neutrons were not charged particles.

Another thing does anyone know of a threshold dose for genetic mutations?

[pm79]

I believe when referring to LET and neutrons, indirectly ionizing particles, they are referring to the energy deposited by the charged particles produced when neutrons do interact with a material as well as the secondary ionizations caused by these charged particles.  Someone might want to back me up on this though.

[PWHoppe]

pmoodie is correct specifically LET is defined as " A measure of the ability of biological material to absorb ionizing radiation; specifically, for charged particles traversing a medium, the energy lost per unit length of path as a result of those collisions with electrons in which the energy loss is less than a specified maximum value. A similar quantity may be defined for photons."

Not sure what you are looking for as as a threshold dose for genetic mutation but BEIR V estimates that at least 100 RAD of low dose rate low LET radiation is required to double spontaneous mutation ratio in man.