(See Energy Level Diagrams for 15C)
The half-life is 2.25 ± 0.05 sec (1956DO37), 2.49 ± 0.07 sec (1964NE09). The β-spectrum is complex. Transitions have been observed both to the ground state and to the upper of the 5.3 MeV levels of 15N: the latter transition is clearly allowed: see Table 15.2 (in PDF or PS) (1959AL06, 1966AL12, 1969GA05). The ground state transition of 15N*(5.3) has Eγ = 5.29903 ± 0.00043 MeV (1967CH19); Jπ for this state is 1/2+ (see Table 15.4 (in PDF or PS)). Thus Jπ(15C) = 1/2+ or 3/2+ (1959AL06, 1964AL21: see also (1965WA03)). See also (1963KI1B,, 1968ZH1B) and 15N.
9Be was irradiated with 14 MeV neutrons and the decay of 11Be was observed [9Be(n, α)6He, followed by the above reaction]: the cross section (which is determined for a large 6He energy spread) is 11 ± 10 mb (1967ST21).
Observed proton groups are listed in Table 15.3 (in PDF or PS) (1957MU99, 1964CA05). τm for 15C*(0.75) is (3.77 ± 0.11) nsec (1968ME08: delayed coincidence technique). Angular distributions of the protons to 15C*(0, 0.75) are reported at E(7Li) = 5.6, 5.8, 6.0, 6.2 MeV by (1969SN02).
Identification of 15Cg.s. with 15N*(11.62), T = 3/2, Jπ = 1/2+, is suggested by (1956BA16). At Ed = 14.9 MeV, proton groups are observed to the ground state of 15C and to the levels at 0.75, 3.09, 4.21, 5.94, 6.38 and 7.32 MeV (± 30 keV) (1959MO1B). The angular distribution of ground state protons implies ln = 0, Jπ = 1/2+ (1959MO1B: see also (1961PU1B) and ref. 9 there, (1964AL21)); for the first excited state, ln = 2. θ2 = 0.093 and 0.032 (1959MO1B), 0.16 and 0.063 (1966GL01) for the ground state and the first excited state, respectively. See also (1967NE06).
The 0.75 MeV level has a mean life of 3.73 ± 0.23 nsec (1962LO02); Eγ = 750 ± 7 keV. The angular distribution of the γ-rays requires J ≥ 5/2. Since the ln = 2 stripping requires Jπ = 3/2+ or 5/2+, Jπ = 5/2+ is established (1962CH14). The observed lifetime excludes J > 5/2 (1962LO02). See also (1964NE09, 1965WA03, 1966AL12, 1967CH19).
The capture cross section is < 1 μb (1951YA1A).
The following reactions leading to 15C have not been reported: