  Ionization chambers working in ambient air in current detection mode are
widely used in several applications such as smoke detection, dosimetry,
therapeutic beam monitoring and cetera. The aim of this work was to investigate
if gaseous detectors can operate in ambient air in pulse counting mode as well
as with gas amplification. . To investigate the feasibility of this method two
types of open- end gaseous detectors were build and successfully tested. The
first one was a single wire or multiwire cylindrical geometry detector
operating in pulse mode at a gas gain of 1. The second type alpha detector was
an innovative GEM-like detector with resistive electrodes operating in air in
avalanche mode at high gas gains (up to 10E4). A detailed comparison between
these two detectors is given as well as comparison with the commercially
available alpha detectors. The main advantages of gaseous detectors operating
in air in a pulse detection mode are their simplicity, low cost and high
sensitivity. One of the possible applications of these new detectors is alpha
particle background monitors which, due to their low cost can find wide
application not only in houses, but in public areas: airports, railway station
and so on.
