¥The original muon lifetime was measured by Rossi and
Hall by comparing the muon absorption of air and dense absorbers (with
equivalent stopping powers).
¥The previously observed anomalous stopping of muons in
air was assumed to be due to the decay of muons.
¥Based on carefully measured muon rates at
different altitudes, with and without absorbers, Rossi and Hall obtained a
lifetime of 2.4 ± 0.3 µs.