particles. Outside the nucleus, free neutrons are unstable and have a meanlifetime of 877.75+0.50 −0.44 s or 879.6±0.8 s (about 14 min and 37.75 s or 39
designs. This value should only be understood conditionally as the “meanlifetime” (an average value), and not as a quantitative identity between working
0969 GeV/c2, just above that of the η c (2.9836 GeV/c2), and a meanlifetime of 7.2×10−21 s. This lifetime was about a thousand times longer than expected. Its