Investigations about the critical radius of the BF3 counters

In disagreement with results obtained by the authors A. Milojevic, M. Kurepa and S. Ribnikar 5 ), we have not found any critical radius in the investigated BF 3 proportional counter. Alpha-particles were introduced parallel with the anode into the mica end-window counter filled with BF 3 -gas of Hgmm 150, and the radial change of the number of impulses was thus studied. In the counter filled with BF 3 -gas Hgmm 150 and 300, the integral amplitude distribution was investigated in the function of electronic amplification at various distances of the source from the anode. The result obtained by Milojevic and collaborators may be due to the impurity of the gas used.