Evening star., 1952-12-02
10 Yeors Of Atomic Research =
A-Bomb Story Actually Began
In Paris Laboratory in 1896

| for a method Of utilizing atomic
energy.
An atomic chain reaction may
be compared to the burning of a
rubbish pile from spontaneous
combustion. In such a fire, min
ute parts Of the pile start to burn
and in turn ignite other tiny frag-
ments. When sufficient numbers
of these fractional parts are
heated to the kindling point, the
entire heap bursts into flames.
A similar process takes place in
an atomic pile such as was con-
structed under the west stands of
Stagg Field at the University of
Chicago in 1912.
The pile itself was constructed
OF uranium, material that is
embedded in matrix of graphite.
With sufficient uranium in the
pile. the few neutrons emitted in
single fiSsion that may acci-
dentally occur strike neighbor-
ing atoms, which in turn undergo
f1sSion and produce more neutrons.
These lombard other atoms and
so on at an increasing rate until
the atomic fire" is going full
blast
The atomic pile is controlled
and prevented from burning itself
Ito complete destruction by cad
MUM rods which absorb neutrons
and stop the bombardment pro-
cess. The same effect might be
achieved by running a pipe of
cold water through a rubbish
heap; by keeping the temperature
low and the pipe would prevent
the spontaneous burning.
Was Result Of Hard Work.
The first atomic chain reaction
experiment was designed to pro-
ceed at a slow and comfortable
rate. In this sense it differed from
the atomic bomb. which was de-
signed to proceed at as fast a rate
as was possible. Otherwise, the
basic process is similar to that of
the atomic bomb.
The atomic chain reaction was
the result Of hard work by many
hands and many heads
Arthur H. Compton, DR.. Zinn,
DR.. Anderson, DR.. Szilard, Eugene
Wigner and many others worked
directly on the problem at the
University Of Chicago. Very many
experiments and calculations had
to be performed.
Finally. a plan was decided
upon. Thirty piles" Of less than
the size necessary to establish a
chain reaction were built and
tested. Then the plans were made
for the final test Of q full-sized
pile.
The scene Of this test under the
west stands at the University of
Chicago campus would have been
confusing to an outsider-if he
could have eluded the security
guards and gained admittance. He
would have seen only what ap-
peared to be crude pile of black
bricks and wooden timbers. All
but one side of the pile was OBJ
scured by grey balloon cloth en-
velope.s
This balloon, which was cubic
in shape. had provided the staff
some secret enjoyment at the ex-
pense Of the Goodyear Tire e.
Rubber Co. which had manufac-
ftured it. The balloon was de-
signed to permit the evacuation
Eof air from the pile but security,
provisions did not permit telling
even the Goodyear designers of
this. They built it under the IL
lusion that the Army was going to
try to fly square balloon.
AS the pile grew toward its final
shape during the days of prepara-
ton, the measurement performed
many times a day indicated that
everything was going. if any
thing, little bit better than pre-
dicted by the calculations.
Finally, the day came when we
were ready to run the experiment.
We gathered on a balcony about
10 feet above the floor of the large
room in which the structure had
been erected.
Beneath us was q young SCI
enlist. George Well. whose duty it
was to handle the last control rod
that was holding the reaction in
check.
Every PrecautiOn Taken.
Every precaution had been
taken against an accident. There
were three sets of control rods in
the pile. One set was automatic.
Another consisted of a heavily
weighted emergency safety held
by a rope. DR.. Zinn, was holding
the rope ready to release it at
the least sign Of trouble. The last
rod left in the pile, which acted
as starter. accelerator and brake
for the reaction, was the one
handled by Mr.. Well.
Since the experiment had never
been tried before, a Liquid control