When embedded in an atomic nucleus, neutrons are (usually) stable particles. Outside the nucleus, free neutrons are unstable and have a mean lifetime of 877.75 +0.50 −0.44 s or 879.6 ± 0.8 s (about 14 min and 37.75 s or 39.6 s, respectively). Therefore, the half-life for this process (which differs from the mean lifetime by a factor of ln (2) ≈ 0.693) is 611 ± 1 s (about 10 min, 11 s).