A two-dimensional gas-scintillation drift chamber for heavy-ion detection

A scintillation drift chamber operated with a gas mixture of 90% Ar + 10% N2 in the range of pressure between 50 and 150 torr is described. The position where a heavy ion transverses the chamber is determined in one dimension from the drift time of ionization electrons measured as the time delay between primary and secondary scintillation flashes; the other dimensions is derived by charge-division techniques from the charge of the electron swarm arriving at the end of the drift space. ΔE signals for particle identification were derived from both the collected charge and the total light amplitude. With 136Xe and 238U ions of 1.4 MeV/amu, position resolution, pulse height and pulse-height resolution were studied systematically. Best resolutions obtained were 0.5 mm and 0.3 mm, respectively, for the two dimensions and 4.7% for ΔE.