

A368860


Number of betastable isotones of neutron number n.


8



1, 2, 1, 2, 2, 2, 2, 2, 2, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 0, 5, 0, 3, 1, 3, 1, 3, 1, 4, 1, 4, 1, 3, 1, 3, 0, 3, 1, 3, 0, 4, 1, 4, 1, 4, 0, 4, 1, 4, 1, 5, 1, 4, 1, 3, 2, 3, 1, 5, 1, 4, 0, 4, 1, 4, 1, 2, 1, 3, 1, 4, 0, 4, 1, 5, 1, 3, 1, 5, 1, 3, 1, 7, 1, 3, 2, 3, 1, 5, 0, 5
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OFFSET

0,2


COMMENTS

A betastable nuclide is a nuclide whose beta decay (betaminus and betaplus decay) is energetically disallowed; that is to say, a nuclide that has lower energy than its isobars with one more or one less proton. Note that double beta decay is allowed. A nuclide whose beta decay is energetially allowed, even if not observed (in the case of 48Ca, 96Zr, 123Te, 148Gd, 180mTa, 222Rn and 247Cm), is not classified as being betastable.
We know 2 betastable isotopes with 160 neutrons (260Fm and 262No), but the unobserved nuclides 258Cf, 261No and 264Rf could be betastable as well.
Different from A318998: for N <= 126, 5He, 8Be, 146Sm, 150Gd, 154Dy, 210Po and 212Rn are betastable but not primordial. 40K, 48Ca, 50V, 96Zr, 113Cd, 115In, 123Te, 138La, 176Lu, 187Re and 180mTa are primordial but not betastable.
a(n) >= 2 for even 4 <= n <= 160, with a(n) = 2 for n = 4 (7Li and 8Be  the latter having an extremely short halflife), 6 (11B and 12C), 8 (15N and 16O), 66 (114Cd and 116Sn), 120 (198Pt and 200Hg) and 128 (212Po and 214Rn  both very unstable to alpha decay). a(82) = 7, and a(n) = 5 for n = 20, 50, 58, 74, 78, 88 and 90.
a(n) = 2 for odd n = 1 (2H and 3He), 3 (5He and 6Li  the former having an extremely short halflife), 5 (9Be and 10B), 7 (13C and 14N), 55 (97Mo and 99Ru) and 85 (145Nd and 147Sm). Page 12 of the Zagrebaev et al. link predicts that a(181) = 2 (corresponding to 293Cn and 295Fl).
Prediction of a(159)a(187) from a Russian source: 1, 3, 1, 3, 1, 3, 1, 3, (0, 3 or 1, 2), 1, 4, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1.
Prediction of a(159)a(209) from pages 1415 of the Hiroyuki Koura link: 0, 5, 1, 3, 1, 4, 1, 4, 1, 4, 1, 3, 1, 5, 1, 4, 1, 5, 1, 4, 1, 5, 1, 4, 0, 6, 1, 4, 1, 3, 1, 4, 0, 4, 1, 4, 1, 3, 1, 5, 1, 3, 1, 4, 1, 3, 1, 4, 1, 2, 1.


LINKS



EXAMPLE

a(56) = 3 because the betastable nuclides with 56 neutrons are 98Mo, 100Ru and 102Pd. Note that 96Zr is not betastable even if its beta decay has never been observed.
a(88) = 5 because the betastable nuclides with 88 neutrons are 148Nd, 150Sm, 151Eu, 152Gd and 154Dy, with the last one being not primordial.
a(126) = 4 because the betastable nuclides with 126 neutrons are 208Pb, 209Bi, 210Po and 212Rn, with the last two being not primordial.
a(158) = 4 because the betastable nuclides with 158 neutrons are 256Cf, 258Fm, 259Md and 260No.


CROSSREFS



KEYWORD

nonn,fini,hard


AUTHOR



STATUS

approved



