control of the reactor. A few experimental fission counting chambers have been
used. These are parallel plate chambers using three circular plates on which. U235
has been deposited electrolytically. These plates are available from the K-25
B. Boron can be most easily deposited on the walls of an ion chamber if it
is in the form of an oil slurry. It is available in such a form through the
at about $16.00 par grain.
C. Aluminum, steel, or graphite all make satisfactory chamber material for
coating by the above process. Some chambers, in fact, use steel and aluminum in
the same chamber. In the judgment of
steel as a chamber material.
D. A normal boron chamber having a diameter of 3 inches and a length
of 30 inches produces a current of 270 microamperes, when one end is in a flux
of 1011n/cm² sec. The position of this chamber is such that the flux gradient is
great so that the mean flux is considerably less than the stated value.
E. A compensated chamber consisting of two identical chambers, one coated
with boron and the other uncoated has been developed to minimize the gamma
observed that this chamber reduces the gamma background by a factor of 107.
Information on this chamber is available from
F. It has not been necessary to use rigid coax to the detectors of the