Drift chamber for the registration of strongly ionizing particles

A drift chamber filled with the mixture He$sup 4$+CO$sub 2$ or He$sup 4$+CH$sub 4$, intended for the registration of strongly ionizing particles was investigated. The chamber has high coordinate and time resolution (sigma/subk/ approximately-less-than 0.2 mm, $delta$t approximately equals 80 nsec). The electron drift velocities were measured for the mixtures He$sup 4$+(5, 10, 20, 30) % CH$sub 4$ and He$sup 4$+(5, 10, 20, 30) % CO$sub 2$. It is shown that if the chamber is filled with He$sup 4$+CH$sub 4$ the registration efficiency is approx. 100% over the entire width of the drift gap.