Dosimetry with a recombination chamber in outdoor conditions and at low dose rates

A system with a recombination chamber for outdoor dosimetry in mixed radiation fields is proposed. The chamber works as a passive detector, with polarising electrodes supplied from capacitors permanently connected to the electrodes. Ions, collected on the measuring electrode, charge a measuring capacitor, also permanently connected to the electrode. A special procedure, including recharging of the supplying capacitors, was introduced in order to compensate the side charge caused by changes of ambient temperature and leakage of the electrical charge from the supplying capacitors. Experimental tests indicated that the chamber of REM-2 type or a specially designed KR-20 chamber could also be used at low dose rates. It was possible to measure the ambient dose of a fraction of μGy with accuracy of about 10%, and the H*(10) of about 1 μSv, with accuracy better than 25%, in any field of penetrating radiation, provided the time of charge collection is less than 24 h.