
^{12}Be (1985AJ01)(See Energy Level Diagrams for ^{12}Be) GENERAL: See also (1980AJ01) and Table 12.1 [Table of Energy Levels] (in PDF or PS). Theoretical papers:(1979KO29, 1981AV02, 1981SE06, 1982NG01, 1983ANZQ, 1983MI1E, 1984VA06). Hypernuclei:(1980GA1P, 1982IK1A, 1982KA1D, 1982PO1C, 1983BR1E, 1983DO1B, 1983MI1E, 1984DO04). Other topics:(1983OL1A, 1983WI1A, 1984HI1A). Mass of ^{12}Be: The Qvalue of the ^{10}Be(t, p) reaction (4809 ± 15 keV) (1978AL29) leads to an atomic mass excess of 25077 ± 15 keV for ^{12}Be.
The halflife of ^{12}Be is 24.4 ± 3.0 msec (1978AL10): log ft = 3.84 ± 0.06 (M.J. Martin, private communication), assuming the decay is to ^{12}B_{g.s.}. The upper limit to a branch involving delayed neutrons is 1% (1978AL10).
At E_{t} = 12 MeV ^{12}Be*(2.10) is populated [E_{x} = 2110 ± 15 keV] and (p, γ) angular correlations lead to J = 2 (1978AL10). At E_{t} = 17 MeV proton groups are observed to the states shown in Table 12.1 (in PDF or PS). The energy of ^{12}Be*(2.10) is measured to be 2089 ± 20 keV. The two highest states have an appreciable intrinsic width. From the measured atomic mass excess of ^{12}Be, d, the cubic factor in the IMME, is calculated to be +2.8 ± 8.6 keV and the first T = 2 state in ^{12}N should occur at E_{x} = 12.27 ± 0.04 MeV (1978AL29): compare with ^{12}O. See also (1980AJ01).
See (1980NA12, 1980NA1D). See also (1980AJ01).
At E(^{14}C) = 60 MeV ^{12}Be*(0, 2.10, 2.68 ± 0.03) have been populated, the latter weakly. Angular distributions are poorly fitted by DWBA. An assignment of 0^{+} is plausible but not proven for ^{12}Be*(2.69) (1982BE42).
