em,
and what the old man said was the law.

It was Costa who spoke first. "Can you brief me on Himmel--what we'll
find there, and be expected to do?"

"Run the basic survey first, of course," Neel told him. "Chances are
that that will be enough to straighten things out. Since the completion
last year of the refining equations of Debir's Postulate, all sigma-110
and alpha-142 graph points are suspect--"

"Just stop there please, and run the flag back down the pole." Costa
interrupted. "I had a six-months survey of Societics seven years ago, to
give me a general idea of the field. I've worked with survey teams since
then, but I have only the vaguest idea of the application of the
information we got. Could you cover the ground again--only a bit
slower?"

Neel controlled his anger successfully and started again, in his best
classroom manner.

"Well, I'm sure you realize that a good survey is half the problem. It
must be impartial and exact. If it is accurately done, application of
the k-factor equations is almost mechanical."

"You've lost me again. Everyone always talks about the k-factor, but no
one has ever explained just what it is."

Neel was warming to his topic now. "It's a term borrowed from
nucleonics, and best understood in that context. Look, you know how an
atomic pile works--essentially just like an atomic bomb. The difference
is just a matter of degree and control. In both of them you have
neutrons tearing around, some of them hitting nuclei and starting new
neutrons going. These in turn hit and start others. This goes on faster
and faster and _bam_, a few milliseconds later you have an atomic bomb.
This is what happens if you don't attempt to control the reaction.

"However, if you have something like heavy water or graphite that will
slow down neutrons and an absorber like cadmium, you can alter the speed
of the reaction. Too much damping material will absorb too many neutrons
and the reaction will stop. Not enough and the reaction will build up to
an explosion. Neither of these extremes is wanted in an atomic pile.
What is needed is a happy balance where you are soaking up just as many
neutrons as are being generated all the time. This will give you a
constant temperature inside the reactor. The net neutron reproduction
constant is then 1. This balance of neutron generation and absorption is
the k-factor of the reactor. Ideally 1.0000000.

"That's the ideal, though, the impossible to attain in a