To assess a radiation contamination of the environment the easiest instrument is the evaluation of the external gamma radiation. The next important assessment of the environment is the aerosol activity which finally in the air of the ground-level atmosphere is inhaled by people for this is all above the alpha- and beta activity the criterion.

The use of aerosol measuring instruments, which are able to work under the same conditions as the gamma stations so far failed primarily on the price and the possibility of establishing such facilities outdoor.
The ERAC is a fully automatic continuously working measuring instrument for the measuring of the alpha and beta activity as well as the gamma radiation which can be used both in radiation early warning systems and for the monitoring of radon concentration in buildings and outdoor.

Measurement principle:
With a commercial fan as used in PCs the air is sucked over an ionization distance while a large part of the aerosols respectively dust particles are deposited on commercial aluminium foil. The aluminium foil is gradually forwarded. For the gamma activity a proportional counting tube is designed below the foil. Above the aluminium foil a semi-conductor diode strip is ordered which measures both the alpha spectrum as well as the beta-radiation. The measurement in 2 steps (every 10 minutes an evaluation is made):
1. Step: The fan and the ionization section are switched on and at the same time the gamma radiation is measured.
2. step: The fan and the ionization section are switched off and the alpha-, beta- and as well the gamma measurement are made.

For the data evaluation in the control centre has been developed our software BITT SCADA (Supervisory Control And Data Acquisition). With BITT SCADA the collection, transfer, evaluation, visualization and storing of all data is easily possible as well as the control of all stations.

The ERAC has been tested outdoor for two years, where the operational readiness in parallel with a conventional glass fibre filter aerosol measuring unit was compared. The fluctuating concentration of 222 Rn at ERAC has shown the same course.

Application method:
Recording of the Rn 222 concentration in the environment, in-door, in waterworks and in thermals as well as in earthquake –dangerous areas for the earthquake warning.

The instrument is also ready for the measurement of artificial radio nuclides, especially plutonium 239.
The detection limit for artificial nuclides will be evaluated and the LD (Limit of Detection) is also displayed graphically.
This figure is important because the natural radon levels in the environment can vary strongly.

Service and maintenance only required every 6 months.