Emanation symbol

edit

One sometimes finds the symbol Em when this was the element's name; I wonder if it goes back to Rutherford? Double sharp (talk) 12:22, 3 February 2021 (UTC)Reply

Comparison of three even-even nuclides with medium beta decay half-lives

edit
Decay process Qβ (keV) Spin change Half-life (a)
202Pb → 202Tl 49.7 0+ → 2JΔπ = 2, 1 forbidden unique) 5.25×104
222Rn → 222Fr 24 0+ → 2JΔπ = 2, 1 forbidden unique) 6.7×104−2.4×108 (predicted)
250Cm → 250Bk 37.7 0+ → 2JΔπ = 2, 1 forbidden unique) 1.04×105

129.104.241.162 (talk) 03:26, 6 March 2024 (UTC)Reply

Note that 205Pb → 205Tl is a 5/2 → 1/2+ process, which is also 1 forbidden unique, with a Q value of 50.5 keV. But its EC half-life is 3 orders of magnitude higher than that of 202Pb... So there is really nothing certain regarding beta decays :) 103.166.228.86 (talk) 08:45, 1 September 2024 (UTC)Reply