This paper introduced a plastic track detector. It was applied for measuring the cumulative expoure of radon and its daughters in mine and environment.

According to the maximum energy loss of

a

particles in polycarbonate plastic the sensitive volume of detection can be increased. First the plastic foil is corroded and then we get magnified tree tracks with electrical chemical etching

the corresponding expoure was determined from the measured track densities.

The detectors were calibrated in a laboratory radon chamber. The calibration factor has been measured to be 11 tracks/cm

2

-WLH

depending on equilibrium factor F. The low limit and upper limit of the detection are 0.5 WLH and 50 WLM

respectively.