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15C (1959AJ76)
(See the Energy Level Diagram for 15C)
GENERAL: See also Table 15.1 [Table of Energy Levels] (in PDF or PS).
Mass of 15C: From the Q of the 14C(d, p)15C reaction given by (1956DO41) (Q0 = -1.007 ± 0.001 MeV), and using the Wapstra masses for 14C, d and 1H, the mass excess of 15C is 14.305 ± 0.005 MeV. Application of Coulomb corrections indicates an excitation of 11.72 to 11.87 MeV for the first T = 3/2 state of 15N (1956BA16, 1956DO37, 1957MU99).
| 1. 15C(β-)15N | Qm = 9.777 |
The half-life is 2.25 ± 0.05 sec. The β-spectrum is complex, with 32 ± 2 % of transitions (log ft = 6.0) to the 15N ground state (Eβ(max) = 9.82 ± 0.04 MeV) and 68% (log ft = 4.1) to the upper of the 5.3 MeV levels of 15N. A 5.299 ± 0.006 MeV γ-ray is observed (1959AL1M): no other γ-rays with Eγ > 5.3 MeV are observed with intensities > 5%, and the intensity of a 1.9 MeV γ-ray (expected if the 15N*(7.16) level were involved) is < 10% (1956DO37). The internal pair conversion coefficient of the 5.30 MeV γ-ray is consistent with E1. All data are consistent with J = 1/2+ for the 5.305 MeV state in 15N and J = 1/2+ for 15C (1959AL1M). See also (1955AJ61, 1956BA16, 1956DO37).
| 2. 9Be(7Li, p)15C | Qm = 9.098 |
At E(7Li) = 2.0 MeV (θ = 90°) proton groups are observed corresponding to the ground state of 15C and to excited states at 0.62 ± 0.06, 2.48 ± 0.05, 3.08 ± 0.04, 4.26 ± 0.04, 5.93 ± 0.04, 6.58 ± 0.04, and 8.16 ± 0.06 MeV. The ground state Q is 9.04 ± 0.05 MeV (1957MU99). In an earlier experiment, (1957NO14) found Q0 = 9.05 ± 0.05 and Q1 = 8.35 ± 0.05 MeV (Ex = 0.70 ± 0.05 MeV). Calculation of Coulomb and (n - 1H) energy difference places the analogue state of 15N at 11.72 to 11.87 MeV. Identification with the known J = 1/2+; T = 3/2 level of 15N at 11.61 MeV supports J = 1/2+ for 15Cg.s. (1956BA16, 1957MU99, 1957NO14).
| 3. 14C(d, p)15C | Qm = -1.007 |
| Q0 = -1.007 ± 0.001 (1956DO41). |
Identification of 15Cg.s. with 15N*(11.62), Jπ = 1/2+; T = 3/2, is suggested by (1956BA16). Proton groups corresponding to the ground state and to levels at 0.7 ± 0.1 and 6.2 ± 0.15 MeV are reported by (1958MO95). The weak activity previously reported at Ed < 1.3 MeV, indicating a Q ≈ 0.1 MeV (see (1955AJ61)), is now attributed to contamination (1956BO1L). See also 16N.
| 4. 14C(n, γ)15C | Qm = 1.220 |
The capture cross section is < 1 μb (1951YA1A, 1955HU1B, 1958HU18).
The following reactions leading to 15C are not reported: 13C(t, p)15C (Qm = 0.909), 14C(t, d)15C (Qm = -5.039), 14C(α, 3He)15C (Qm = -19.358), 15N(n, p)15C (Qm = -8.994), 18O(n, α)15C (Qm = -5.024).