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GENERAL: See 18.1 [General Table] (in PDF or PS) and 18.2 [Table of Energy Levels ] (in PDF or PS).

Mass of ¹⁸C: The atomic mass excess of ¹⁸C adopted by (1993AU05) is 24.920 ± 0.030 MeV, based on the Q-value of the ⁴⁸Ca(¹⁸O, ¹⁸C)⁴⁸Ti reaction. ¹⁸C is then bound by 4.188 MeV with respect to breakup into ¹⁷C + n. See also (1982FI10, 1987AJ02, 1992WA22).

1. 18C(β-)18N

Qm = 11.807

The half-life of ¹⁸C has been measured to be 66⁺²⁵_-18 ms (1988MU08), 78⁺²⁰_-15 ms (1989LE16), 94 ± 27 ms (1991RE02), (95 ± 10) ms (1991PR03).

Branching to states in ¹⁸N has been measured by (1991PR03) and is presented here in 18.6 (in PDF or PS). These authors also measured the total branching probability to gamma emitting states plus the ground state of ¹⁸N to be P_γ = (81 ± 5)%. The β-delayed neutron emission probability is P_n = 1 - P_γ = (19 ± 5)%. Other values reported for P_n are (25 ± 4.5)% (1988MU08), (50 ± 10)% (1989LE16), (43.3 ± 6.5)% (1991RE02). The ¹⁸C(β^-) decay is also discussed in the analysis of Gamow-Teller rates presented in (1993CH06). Experimental Gamow-Teller matrix elements are compared with results of shell-model calculations.

2. 18O(π-, π+)18C

Qm = -25.706

The angular distribution of the π⁺ to the ground state of ¹⁸C has been measured at E_π^- = 164 MeV by (1984GI10) [see also for excitation function at θ = 5° for E_π^- ≈ 140 to 240 MeV]. There is also some indication of the population of an excited state at E_x = 1.55 MeV (1984GI10). See also (1983AJ01).

3. 48Ca(18O, 18C)48Ti

Qm = -21.434

At E(¹⁸O) = 112 MeV the ground state and an excited state at 1.62 ± 0.024 MeV are observed by MeV (1982FI10). See also (1983AJ01).