What gas filled counter has the worst resolving time?

The gas-filled counter with the worst resolving time is typically the ionization chamber. This is because ionization chambers operate by collecting charges produced by ionizing radiation, which leads to a slower response time compared to other types of gas-filled detectors, such as Geiger-Müller counters or scintillation detectors. Their design prioritizes measuring high radiation levels over fast response, resulting in longer resolving times.