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GENERAL: See also (84AJ01) and Table 6.1 [Table of Energy Levels] (PDF or PS) here.

Model calculations: (83GA1E, 83LE14, 84FI1E, 84PA08, 84VA06, 85EM01, 85FI1E, 86EM1A, 86FI1F, 86KU08, 86KU1F, 86VA13, 86VO09, 87DA1H, 88KA1J).

Special states: (84FI1A, 84FI1E, 84VA06, 85EM01, 85FI1E, 86EM1A, 86FI1F, 86KU08, 86VA13, 86VO09, 86WI04, 87BL18, 87DA1G, 87DA1H, 87KO39, 87KU1F, 88DA1E).

Electromagnetic transitions: (84VA1B, 85FI1E, 86FI1F).

Complex reactions involving ⁶He: (82AL1C, 83AN13, 83KU1B, 83OL1A, 84BA1H, 84GL1E, 84KO1A, 84LA27, 84WE03, 85BA1C, 85BO1J, 85JA1B, 85MA02, 85MA13, 85WO11, 86AV1B, 86CS1A, 86EN1B, 86MA1V, 86SA30, 86SI1B, 86WE1C, 87BA1I, 87BA39, 87BO40, 87GR11, 87GU1L, 87KO1Z, 87PE1C, 87TA1F, 87WI09, 87YA16, 88AL1G, 88LI1A, 88ST06, 88TA1A, 88WO10).

Applications: (85TA1D).

Muon and neutrino capture and reactions: (83JU01, 84WA1J).

Reactions involving pions, other mesons and baryon states (see also reactions 4 and 5): (82BE1D, 84KO16, 84RE1C, 84ZA1A, 85ER06, 85RE1B, 86AK1A, 86HA1L, 87FA1H, 87JA1C).

Hypernuclei: (82KA1D, 82MO1B, 82WA1A, 83BA1D, 83MO1C, 83SH1E, 84BO1D, 84BO1G, 84BO1H, 84CH1G, 84DZ1A, 84KE1C, 84MI1E, 84MO1H, 84ZH1B, 85BA1E, 85GU1J, 85IK1A, 85MO1F, 86BO1E, 86DA1B, 86PO1G, 86PO1H, 86WA1J, 86ZH1B, 87BO1L, 87BO1O, 87CO1S, 87DZ1B, 87JI1A, 87PO1H, 87SU1K, 87WA1J, 87YA1M, 88GI1B, 88JI1A, 88PO1H, 88TA1B).

Other topics: (83BA1L, 84FI1E, 85AN28, 86KO1N, 86KU1F, 87AJ1A, 88DA1E).

Ground state of ⁶He: (83ANZQ, 83GR26, 83LE14, 84FR13, 84PA08, 85AN28, 85FI1E, 85SA32, 86KU08, 86VO09, 87BL18, 87HA30, 87HA34, 87SA15, 88DAZW, 88JO1C).

The interaction nuclear radius of ⁶He is 2.18 ± 0.02 fm (85TA18, 85TA13) [see also for derived nuclear matter, charge and neutron matter rms radii].

1. 6He(β-)6Li

Qm = 3.507

The decay proceeds to the ground state of ⁶Li [J^π = 1⁺] via a super-allowed Gamow-Teller transition. The half-life is 806.7 ± 1.5 msec; log ft = 2.910 ± 0.002: see (84AJ01). See also (86RO1L), (85GR1A) and (83LE14, 84BO03, 84PA08, 88SA2J; theor.).

2. (a) 3H(t, n)5He	Qm = 10.44	Eb = 12.307
(b) 3H(t, 2n)4He	Qm = 11.33216
(c) 3H(t, t)3H

The cross section for reaction (b) has recently been measured for E_t = 30 to 115 keV by (86BR1K, 85JA16) who have also calculated the astrophysical S-factors [the extrapolated S(0) ~ 180 keV · b] and discussed the earlier measurements. See also (74AJ01, 79AJ01) and (86JA1E; applied). For muon-catalyzed fusion see (85ZI1C, 87BR1V, 87PO1M). See also (84BY1A, 84BY1B, 84FI1F, 85BU1B, 85GU1G, 85KA1M, 85VA1B, 86BA73, 86BY1A, 87PR08, 87WY1A, 88RIZW; theor.).

3. 4He(t, p)6He

Qm = 7.507

Angular distributions of the protons to ⁶He*(0, 1.80) have been measured at E_t = 22 and 23 MeV. [No L-values were assigned.] No other states are observed with E_x < / = 4.2 MeV: see (79AJ01).

4. 6Li(e, π+)6He

Qm = 143.075

(86SH14) report breaks in (e, π⁺) spectra at E_e = 202 MeV corresponding to E_x = 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 [J^π = 1^-, 2^-]. For the earlier work see (84AJ01). [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].

5. (a) 6Li(π-, γ)6He	Qm = 136.062
(b) 6Li(π-, π0)6He	Qm = 1.097

The excitation of ⁶He*(0, 1.8) and possibly of (broad) states at E_x = 15.6 ± 0.5, 23.2 ± 0.7 and 29.7 ± 1.3 MeV has been reported: see (79AJ01). (86PE05) have recently studied the capture branching ratios to ⁶He*(0, 1.8). For reaction (b) see (84AJ01).

6. 6Li(n, p)6He

Qm = 2.725

Angular distributions of the p₀ group have been reported at E_n = 4.7 to 6.8 MeV, at 14 MeV and at 59.6 MeV [see (79AJ01, 84AJ01)] and at 118 MeV (87PO18; prelim.). At E_n = 59.6 MeV broad structures in the spectra are ascribed to states at E_x = 15.5 ± 0.5 and 25 ± 1 MeV with Γ$ = 4 ± 1.5 and 8 ± 2 MeV (83BR1C, 84BR03) [see for discussions of the GDR strength]. The ground state reaction has also been studied at E_n = 198 MeV (88JA01). See also (86AL1K, 86PO1J, 88MI1E), (86AU1D, 87BR32, 87HE22, 88HA12) and (83GM1A, 85ER06, 86ER1A; theor.).

7. 6Li(d, 2p)6He

Qm = -4.949

At E_d = 55 MeV, ⁶He*(0, 1.8) [the latter weak] are populated: no other states are observed with E_x < / = 25 MeV [see (84AJ01)].

8. 6Li(t, 3He)6He

Qm = -3.488

The ground-state angular distribution has been studied at E_t = 17 MeV. At E_t = 22 MeV only ⁶He*(0, 1.8) are populated for E_x < / = 8.5 MeV: see (79AJ01). Differential cross sections for the transition to ⁶He*(1.8) are reported at E(⁶Li) = 65 MeV (87AL1L).

9. 6Li(6Li, 6Be)6He

Qm = -7.795

Angular distributions have been studied for E(⁶Li) = 32 and 36 MeV for the transitions to ⁶He_g.s., ⁶Be_g.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 (79AJ01).

10. (a) 7Li(γ, p)6He	Qm = -9.975
(b) 7Li(e, ep)6He	Qm = -9.975

At E_γ = 60 MeV, the proton spectrum shows two prominent peaks attributed to ⁶He*(0 + 1.8, 18 ± 3): see (79AJ01). Reactions (a) and (b) have been studied by (85SE17). See also ⁷Li, (84AJ01) and (86BA2G; theor.).

11. 7Li(n, d)6He

Qm = -7.750

At E_n = 60 MeV, the deuteron spectrum shows two prominent peaks attributed to states centered at E_x = 13.6, 15.4 and 17.7 MeV (± 0.5 MeV) and a possible state or states (populated with an l_p transfer >/= 2) at E_x = 23.7 MeV. DWBA analyses of the d₀ and d₁ groups are consistent with l_p = 1 and S(1p_3/2) = 0.62 for ⁶He_g.s. and to S(1p_3/2) = 0.37, S(1p_1/2) = 0.32 for ⁶He*(1.8): see (79AJ01).

12. 7Li(p, 2p)6He

Qm = -9.975

At E_p = 1 GeV the separation energy between 6 - 7 MeV broad 1p_3/2 and 1s_1/2 peaks is reported to be 14.1 ± 0.7 MeV (85BE30, 85DO16). See also (83GO06) and (79AJ01).

13. 7Li(d, 3He)6He

Qm = -4.481

Angular distributions of the ³He ions to ⁶He*(0, 1.8) have been measured at E_d = 14.4 and 22 MeV: they have an l_p = 1 character and therefore these two states have J^π = (0 - 3)⁺. There is no evidence for any other states of ⁶He with E_x < 10.7 MeV: see (79AJ01). (87BO1W) [E_d = 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 (85BO55) and (87DA1N; theor.).

14. 7Li(t, α)6He

Qm = 9.839

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 Γ_γ/Γ_α < / = 2 x 10^-6: for Γ_c.m. = 113 ± 20 keV, Γ_γ >/= 0.23 eV. Angular distributions of the α₀ and α₁ groups have been measured at E_t = 13 and 22 MeV. No other α-groups are reported corresponding to ⁶He states with E_x < 24 MeV (region between E_x ~ 13 and 16 MeV was obscured by the presence of breakup α-particles): see (79AJ01). Angular distributions have been recently reported at E_t = 0.151 and 0.272 MeV (87AB09; α₀, α₁) and at E(⁷Li) = 31 MeV. (87AL1L; to ⁶He*(0, 1.8, 13.6)).

15. 7Li(3He, p3He)6He

Qm = -9.975

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 E_x = 32.0 and 35.7 MeV, with Γ < / = 2 MeV (85FR01).

16. (a) 7Li(6Li, 7Be)6He	Qm = -4.369
(b) 7Li(7Li, 8Be)6He	Qm = 7.280

In reaction (a) at E(⁶Li) = 93 MeV a broad peak (Γ = 5.5 MeV) is reported at E_x = 14 MeV. A second structure may also be present at 15.5 MeV (87GLZW, 88BUZH; prelim.). ⁶He*(0, 1.8) are also populated (88BU1Q). For reaction (b) see ⁸Be. See also ⁷Be, (84AJ01), (88BU1Q) and (84BA53; theor.).

17. 9Be(n, α)6He

Qm = -0.598

Angular distributions have been reported for E_n = 12.2 to 18.0 MeV (α₀, α₁). No other states are observed with E_x < / = 7 MeV: see (79AJ01). For a study of possible dineutron breakup of ⁶He*(1.8) see (83OT02). See also ¹⁰Be and (83SH1J).

18. 9Be(6Li, 9Be)6He

Qm = -4.575

See ⁹B.

19. 10B(n, pα)6He

Qm = -7.184

Not observed: see (84TU02).

20. 11B(7Li, 12C)6He

Qm = 5.983

At E(¹¹B) = 88 MeV the population of the ground state and the first-excited state at E_x = 1.8 ± 0.3 MeV (Γ < / = 0.2 MeV) is reported (87BEYI). See also (88BEYJ).