Use of quadratic relationship between position and drift time in a cylindrical-type drift chamber

The space–time relationship is desired to be as linear as possible in converting the electron drift time into the incident radiation position. The drift velocity of electrons in practical gases depends on the electric field. P-10 gas (Ar : Methane=90 : 10) which is the most popular for proportional counters was chosen for the cylindrical-type drift chamber. The use of a quadratic relationship allowed us to avoid the complexity of obtaining the position by means of difference in the drift times in pair cells of the cylindrical cell drift chamber. In addition, a method was devised to give a better position resolution by making use of the quadratic function. The cylindrical-type drift chamber has the feature of easy fabrication. It was shown that in a drift chamber of this type the space–time relationship of the quadratic function is derived from the dependence of drift velocity on the electric field.