(See Energy Level Diagrams for 6He)
Complex reactions involving 6He: (1982AL33, 1983AN13, 1983KU1B, 1983OL1A, 1984BA1H, 1984GL06, 1984KO1A, 1984LA27, 1984WE03, 1985BA1C, 1985BO1J, 1985JA18, 1985MA02, 1985MA13, 1985WO11, 1986AV1B, 1986CS1A, 1986EN1B, 1986MA1V, 1986SA30, 1986SIZS, 1986WE1C, 1987BA1I, 1987BA38, 1987BA39, 1987BO40, 1987GR11, 1987GU1L, 1987KO1Z, 1987PE1C, 1987TAZU, 1987WI09, 1987YA16, 1988AL1G, 1988LI1A, 1988ST06, 1988TA1A, 1988WO10).
Hypernuclei: (1982KA1D, 1982MO1B, 1982WA1A, 1983BA1D, 1983MO1C, 1983SH1E, 1984BO1D, 1984BO1G, 1984BO1H, 1984CH1G, 1984DZ1A, 1984KE1C, 1984MI1E, 1984MO1H, 1984ZH1B, 1985BA1E, 1985GU1J, 1985IK1A, 1985MO1F, 1986BO1E, 1986DA1B, 1986PO1G, 1986PO1H, 1986WA1J, 1986ZH1B, 1987BO1L, 1987BO1O, 1987CO1S, 1987DZ1B, 1987JI1A, 1987PO1H, 1987SU1K, 1987WA36, 1987YA1M, 1988GI1B, 1988JI1A, 1988PO1H, 1988TA29).
The decay proceeds to the ground state of 6Li [Jπ = 1+] via a super-allowed Gamow-Teller transition. The half-life is 806.7 ± 1.5 msec; log ft = 2.910 ± 0.002: see (1984AJ01). See also (1986RO27), (1985GR1A) and (1983LE14, 1984BO03, 1984PA08, 1988SA2J; theor.).
The cross section for reaction (b) has recently been measured for Et = 30 to 115 keV by (1986BR20, 1985JA16) who have also calculated the astrophysical S-factors [the extrapolated S(0) ≈ 180 keV · b] and discussed the earlier measurements. See also (1974AJ01, 1979AJ01) and (1986JA1E; applied). For muon-catalyzed fusion see (1985ZI1C, 1987BR1V, 1987PO1M). See also (1984BY1A, 1984BY1B, 1984FI1F, 1985BU1B, 1985GU1G, 1985KA1M, 1985VA1B, 1986BA73, 1986BY1A, 1987PR08, 1987WY1A, 1988RYZW; theor.).
Angular distributions of the protons to 6He*(0, 1.80) have been measured at Et = 22 and 23 MeV. [No L-values were assigned.] No other states are observed with Ex ≤ 4.2 MeV: see (1979AJ01).
(1986SH14) report breaks in (e, π+) spectra at Ee = 202 MeV corresponding to Ex = 7, 9, 12, 13.6, 17.7 and 24.0 MeV. Using the shape of the virtual photon spectrum results in groups whose angular distributions suggest that the states at 13.6, 17.7 and 24.0 MeV are spin-dipole isovector states [Jπ = 1-, 2-]. For the earlier work see (1984AJ01). [Note: The states reported here at 7, 9 and 12 MeV are inconsistent with the work reported in reactions 7, 8, 14 and 15, and with the work on the analog region in 6Be].
The excitation of 6He*(0, 1.8) and possibly of (broad) states at Ex = 15.6 ± 0.5, 23.2 ± 0.7 and 29.7 ± 1.3 MeV has been reported: see (1979AJ01). (1986PE05) have recently studied the capture branching ratios to 6He*(0, 1.8). For reaction (b) see (1984AJ01).
Angular distributions of the p0 group have been reported at En = 4.7 to 6.8 MeV, at 14 MeV and at 59.6 MeV [see (1979AJ01, 1984AJ01)] and at 118 MeV (1987PO18; prelim.). At En = 59.6 MeV broad structures in the spectra are ascribed to states at Ex = 15.5 ± 0.5 and 25 ± 1 MeV with Γ = 4 ± 1.5 and 8 ± 2 MeV (1983BR32, 1984BR03) [see for discussions of the GDR strength]. The ground state reaction has also been studied at En = 198 MeV (1988JA01). See also (1986ALZJ, 1986POZX, 1988MIZX), (1986AU1D, 1987BR32, 1987HE22, 1988HA12) and (1983GM1A, 1985ER06, 1986ER1A; theor.).
At Ed = 55 MeV, 6He*(0, 1.8) [the latter weak] are populated: no other states are observed with Ex ≤ 25 MeV [see (1984AJ01)].
The ground-state angular distribution has been studied at Et = 17 MeV. At Et = 22 MeV only 6He*(0, 1.8) are populated for Ex ≤ 8.5 MeV: see (1979AJ01). Differential cross sections for the transition to 6He*(1.8) are reported at E(6Li) = 65 MeV (1987AL23).
Angular distributions have been studied for E(6Li) = 32 and 36 MeV for the transitions to 6Heg.s., 6Beg.s. and, in inelastic scattering of 6Li [see 6Li], to the analog state 6Li*(3.56): for a discussion of these see the references quoted in (1979AJ01).
At Eγ = 60 MeV, the proton spectrum shows two prominent peaks attributed to 6He*(0 + 1.8, 18 ± 3): see (1979AJ01). Reactions (a) and (b) have been studied by (1985SE17). See also 7Li, (1984AJ01) and (1986BA2G; theor.).
At En = 60 MeV, the deuteron spectrum shows two prominent peaks attributed to states centered at Ex = 13.6, 15.4 and 17.7 MeV (± 0.5 MeV) and a possible state or states (populated with an lp transfer ≥ 2) at Ex = 23.7 MeV. DWBA analyses of the d0 and d1 groups are consistent with lp = 1 and S(1p3/2) = 0.62 for 6Heg.s. and to S(1p3/2) = 0.37, S(1p1/2) = 0.32 for 6He*(1.8): see (1979AJ01).
Angular distributions of the 3He ions to 6He*(0, 1.8) have been measured at Ed = 14.4 and 22 MeV: they have an lp = 1 character and therefore these two states have Jπ = (0 - 3)+. There is no evidence for any other states of 6He with Ex < 10.7 MeV: see (1979AJ01). (1987BO39) [Ed = 30.7 MeV] deduce that the branching ratio of 6He*(1.8) into a dineutron [n2: T = 1, S = 0] and an α-particle is 0.75 ± 0.10. See also (1985BO55) and (1987DA31; theor.).
The energy of the first-excited state is 1.797 ± 0.025 MeV, Γ = 113 ± 20 keV. 6He*(1.80) decays into 4He + 2n. The branching ratio Γγ/Γα ≤ 2 × 10-6: for Γc.m. = 113 ± 20 keV, Γγ ≥ 0.23 eV. Angular distributions of the α0 and α1 groups have been measured at Et = 13 and 22 MeV. No other α-groups are reported corresponding to 6He states with Ex < 24 MeV (region between Ex ≈ 13 and 16 MeV was obscured by the presence of breakup α-particles): see (1979AJ01). Angular distributions have been recently reported at Et = 0.151 and 0.272 MeV (1987AB09; α0, α1) and at E(7Li) = 31 MeV. (1987AL23; to 6He*(0, 1.8, 13.6)).
At E(3He) = 120 MeV the missing mass spectra show 6He*(0, 1.8) and a strong, broad peak corresponding to 6He*(16) [possibly due to unresolved states]. There is no indication of a state near 23.7 MeV but there is some evidence of structures at Ex = 32.0 and 35.7 MeV, with Γ ≤ 2 MeV (1985FR01).
In reaction (a) at E(6Li) = 93 MeV a broad peak (Γ = 5.5 MeV) is reported at Ex = 14 MeV. A second structure may also be present at 15.5 MeV (1987GLZW, 1988BUZH; prelim.). 6He*(0, 1.8) are also populated (1988BUZH). For reaction (b) see 8Be. See also 7Be, (1984AJ01), (1988BU1Q) and (1984BA53; theor.).
Angular distributions have been reported for En = 12.2 to 18.0 MeV (α0, α1). No other states are observed with Ex ≤ 7 MeV: see (1979AJ01). For a study of possible dineutron breakup of 6He*(1.8) see (1983OT02). See also 10Be and (1983SH1J).
Not observed: see (1984TU02).