Medical Applications of 14 MeV Neutrons
464
MCNP should be used to determine the relationship between thickness of
the reecting plane and the ux at the target. From these values, the reection
factor F
R
should be determined by
F
R
= Flux with collimator/ux without collimator (at target)
is denition permits quick comparison of a new geometry to already existing
geometries. Ideal reector would have no leakage in any direction but the tar-
get direction. According to the reecting light with cloud analogy, one would
not see the collimator, unless looked down its axis. A trend line has been t to
the data points for each curve. As expected, the eld diverges nearly as 1/r
2
.
e ratio of ux for the 40cm reector to that with 0cm reector i