Sketch for large values of A, the ratio, as a function of k,
of a) the probability of finding the particle trapped between the
-function and the infinite wall to b) to the rate of particles
incoming from the source. For a fixed value of the incoming beam,
near which values of k do you find the greatest build up of
particles?
Note: to make the algebra simpler, you may work under the limit
that ka>>1 so that 
.