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GENERAL: See also (1974AJ01).

See (1973AL1B, 1973TO16, 1974IR04, 1974MA1E, 1975AB1D, 1975BE31, 1976BE1G, 1976IR1B, 1976VA29, 1978KO1H, 1978NA07).

Mass of ⁸He: The atomic mass excess of ⁸He is 31596 ± 7 keV (1977TR07). See also (1974CE05, 1975JA10, 1975KO18, 1978RO01). ⁸He is then stable with respect to decay into ⁶He + 2n by 2.141 MeV. See also (1974AJ01, 1976TR01) and (1975JE02; theor.). The IMME coefficients based on the latest masses of the T = 2 states in A = 8 are calculated by (1977TR07).

1. 8He(β-)8Li

Qm = 10.649

The half-life is 122 ± 2 msec. The decay takes place 88% to ⁸Li*(0.98) [log ft = 4.19 (M.J. Martin, Nucl. Data Project, private communication.)] [consistent with J^π = 1⁺ for ⁸Li*(0.98)] and (12 ± 1)% via ⁸Li states which decay by neutron emission (1965PO06). See also (1973AN11, 1976DE31).

2. 18O(α, 14O)8He

Qm = -37.962

At E_α = 58 MeV, θ_lab = 8°, the differential cross for formation of ⁸He_g.s. is 40 ± 15 nb/sr (1975JA10).

3. 26Mg(α, 22Mg)8He

Qm = -44.989

This reaction has been studied at E_α = 80 MeV (1966CE01) and 110.6 MeV (1974CE05).