  The gaseous proportional counter is a device that can be used to detect
ionizing radiation. These devices can be as simple as a cylindrical cathode and
a very thin anode wire centered along its axis. By applying a high voltage, a
strong electric field is generated close to the anode wire. Ion-pairs,
generated by passing ionizing radiation, create avalanches once they drift into
the strong electric field region near the anode. The electrical charges created
by the avalanche generate an observable signal which is proportional to the
energy loss of the incoming radiation. We discuss the construction of such a
device. Our detector was built from an ordinary aluminium beverage can and uses
a common electric wire strand as the anode. The construction of this detector
offers students at universities or technically oriented high schools a detailed
understanding of the design and operation of gaseous radiation detectors. The
equipment required to complete the project should be available at most
institutions.
