Neutron dosimetry using ionization chambers. V

Pulsed radiations beams require somewhat more complex measurement methods and interpretation of results using ionization chambers. The results of a study are described of the dosimetric characteristic of pulsed beams of mixed neutron/photon radiation in the biological channel of the IBR-2 reactor at the Laboratory of Neutron Physics of the Joint Institute of Nuclear Research in Dubna near Moscow. The mean width of radiation pulses is around 250 μs, the pulse is repeated with a frequency of 5 Hz. The study was performed using a pair of ionization chambers (tissue-equiva-lent and aluminium) with two different gas fillings. The dosimetric characteristics were studied behind five different shieldings combined of B4C, polyethylene and lead. Special attention was devoted to the saturation properties of the ionization chambers with regard to the type of chamber and the proportion of neutrons and gamma radiation in the beam. Presented and discussed are certain new characteristics of chambers in pulsed radiation beams. (author)