Decay study of20Na and its beta-delayed16O recoiling

High-statistics measurement of the $\beta$ -delayed $\alpha$ spectrum of 20Na

“…At no point during this interval was the vacuum broken. The 8 B and 23 Al measurements are discussed elsewhere [5,11]. The two 20 Na runs give consistent results.…”

“…Data taking was split in two runs, the first lasting 5 hours, the second 7 hours. In between, the setup was used for measuring the decays of 23 Al (8 hours) and 8 B (72 hours). At no point during this interval was the vacuum broken.…”

“…In Table III, we compare the present data to that of Refs. [3,23,24]. The lines are numbered as in our spectrum and letters are used to denote lines quoted in other papers, but not seen by us (as argued below most of these are due to misinterpretations).…”

“…The number of counts as a function of E is then 1 714(4) · · · ∼ 780 a 0.028(4)( +40 −13 ) · · · ∼ 1.4 a 2 847(5) · · · 0.0101(14)( +30 −16 ) · · · 3 1220(30) · · · · · · 0.006(2) · · · · · · 4 1 589(5) 1 580(40) · · · 0.0083(10)(2) 0.020(4) · · · 5 2 153.2 (10) (9) 13 5 698(6) 5 691(4) 0.010(2) 0.012(2) D · · · · · · 5 896(6) · · · · · · 0.002 a The evidence presented in Ref. [23] for the observation of this α group is meager.…”

“…The J π = 2 + , T = 1 ground state of 20 Na decays to 20 Ne by positron emission with a half-life of 447.9 (23) ms and an available decay energy of Q EC = 13 892.5 (11) keV [1]. Excited states in 20 Ne populated in the β decay of 20 Na, with an excitation energy above 4 729.84 keV, may break up to α + 16 O.…”