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GENERAL: See (1960GO1B, 1960ZE03, 1961BA1C, 1961LO07, 1961YA04, 1964GO25, 1965BA1A).

Mass of ⁸He: From the systematics of neutron binding energies (1960GO36) and from the calculated mass excess of ⁷He, the mass excess of ⁸He is estimated as 31.6 to 32.4 MeV. It is thus stable against ⁶He + 2n by 1.3 to 2.1 MeV and should exhibit β^--decay to ⁸Li*(0.98) with E_β(max) = 9.7 to 10.5 MeV (1965DE08).

1. 8He(β-)8Li*

Qm ≈ 10

An activity with half-life 30 ± 20 msec, E_β(max) = 13 ± 2 MeV, observed in ¹¹B + γ (320 MeV), is ascribed to ⁸He (1963NE07). See also (1965PO03).

2. 11B(γ, 3p)8He

Qm ≈ -45

At E_γ(max) = 320 MeV, the production cross section is > 6 μb (1963NE07).