(See Energy Level Diagrams for 11Be)
Muon and neutrino capture and reactions:(1984KO24).
Proton groups have been observed to the states displayed in Table 11.2 (in PDF or PS). τm for the first excited state is 166 ± 15 fs, corresponding to a very large E1 transition strength of 0.36 ± 0.03 W.u.; Eγ = 320.04 ± 0.10 keV. The Jπ of 11Be*(0.32) is 1/2-, as determined by a study of the yield of 320 keV γ-rays as a function of time in μ- capture by 11B. The strength of the E1 transition fixes Jπ of 11Beg.s. to be 1/2+ or 3/2+, using the parity information obtained from the nature of the β- decay of the ground state [see reaction 26 in 11B]. 11Be*(5.24, 6.71, 8.82) are strongly populated at Et = 20 MeV indicating that these states have a large overlap with 9Beg.s. + 2n. See (1980AJ01, 1985AJ01) for references.
Angular distributions of the p0 and p1 groups have been measured at Em = 6 MeV and 12 MeV: ln = 0 [and therefore Jπ = 1/2+ for 11Be(0)] and l, S = 0.73 ± 0.06 and 0.63 ± 0.15, respectively. At Em = 25 MeV 11Be*(0, 0.32, 1.78) are strongly populated: S = 0.77, 0.96, and 0.50, respectively, Jπ = (5/2, 3/2)+ for 11Be*(1.78) [ln = 2]. See (1980AJ01) for references.
The photon spectrum from stopped pions includes a peak corresponding to 11Be*(0 + 0.32) (1986PE05).
See (1987BL07; Eπ- = 145 MeV).
At E(7Li) = 82 MeV 11Be*(0 + 0.32, 1.8, 3.4) are populated (1985AL1G).
At E(6Li) = 80 MeV, 11Be*(0.32) is strongly populated and the angular distribution to this state has been measured. 11Be*(2.69, 4.0) are also observed: see (1980AJ01).