(See Energy Level Diagrams for 18N)
GENERAL: See 3 [Electromagnetic Transitions in A = 18-19] (in PDF or PS), 18.3 [General Table ] (in PDF or PS), 18.4 [Table of Energy Levels] (in PDF or PS) and 18.5 [Radiative decays in 18N] (in PDF or PS).
Mass of 18N: The atomic mass excess derived from the Q-value of the 18O(7Li, 7Be)18N reaction and adopted by (1993AU05) is 13.117 ± 0.020 MeV (1983PU01). 18N is then stable with respect to breakup into 17N + n by 2.825 MeV. See (1983AJ01) for the earlier work.
The half-life of 18N is 0.624 ± 0.012 s (1982OL01). The decay branches are displayed in 18.18 (in PDF or PS). The nature of the decay leads to Jπ = 1- for the 18N ground state (1982OL01). See also (1983SN03), and see the measurements on beta branching reported in (1989ZH04) which indicate a total branching ratio to alpha-particle-emitting states in 18O of at least 12.2%. A delayed-neutron emission probablility Pn = (14.3 ± 2.0)% was measured by (1991RE02). More recently a study reported by (1994SC01) gave Pn = (2.2 ± 0.4)% for transitions to neutron unstable states in 18O above Ex = 9.0 MeV. See also reaction 22 under 18O.
The preliminary work described in (1983AJ01) has not been published.
At E(18O) = 92.2 MeV groups are observed to the ground state of 18N (unresolved) and to an excited state at Ex = 575 ± 25 keV (1980NA14).
See reaction 1 under 18C. Branching to states in 18N was measured by (1991PR03) and is presented here in 18.6 (in PDF or PS). These authors measured the total branching probability to gamma emitting states of 18N to be Pγ = 81 ± 5%. Measurements of γ-ray energies and branching lead to the level energies displayed in 18.7 (in PDF or PS) and 18N radiative decays in 18.5 (in PDF or PS).