β-Delayed Proton Emission ofAl23

Abstract

PHYSICAL REVIEW LETTERS 21 FEBRUARY 1972 critical point. Several other related examples will be reported in a separate paper 6 with detailed arguments on the above models. [As should be the case, spin correlations obtained exactly in the model (1) satisfy Griffiths-Kelly-Sherman inequalities 7 for J k ^ 0 and J k ' ^ 0.] 1 R.The weak 0-delayed proton emitter 23 A1, with a half-life of 470±30 msec, was produced by the reaction 24 Mg(/>,2w) 23 Al. We observed delayed protons with a center-of-mass energy of 870 ± 30 keV and a maximum production cross section ^ 220 nb.

Experimental study ofβ-delayed proton decay ofAl23for nucleosynthesis in novae

“…This reaction rate is dominated by the capture through narrow and isolated low-energy proton resonances, which correspond to the excited states near the proton separation threshold in 23 Mg. The presently accepted reaction rate for 22 Na(p,γ) is based on challenging direct measurements with a radioactive 22 Na target [11,14] supplemented by informa- tion from indirect measurements, via reaction [12,16,22] and β-decay studies [13,15,17].…”

“…At typical nova peak temperatures (0.1-0.4 GK) the main destruction channel for 22 Na is thought to be the radiative proton capture 22 Na(p,γ) 23 Mg. This reaction rate is dominated by the capture through narrow and isolated low-energy proton resonances, which correspond to the excited states near the proton separation threshold in 23 Mg.…”

“…This leads eventually into the MgAl cycle and to a reduced abundance of 22 Na in the end products. The rates of these depleting reactions have been of considerable interest, and recent studies include 21 Na(p,γ) 22 Mg [6,7], 22 Mg(p,γ) 23 Al [8][9][10], 22 Na(p,γ) 23 Mg [11][12][13][14][15][16][17][18], 23 Na(p,γ) 24 Mg [19] and 23 Mg(p,γ) 24 Al [20]. It is believed that novae could become the first type of explosive process for which all the nuclear input to the nucleosynthesis calculations is based on experimental data [21].…”

“…The β-decay of 23 Al populates excited states of 23 Mg that can decay by both proton and γ emission. Proton emission following the β-decay of 23 Al was reported first by Gough et al in Ref. [23], where a single proton line at E p, c.m.…”

“…The presently accepted reaction rate for 22 Na(p,γ) is based on challenging direct measurements with a radioactive 22 Na target [11,14] supplemented by informa- tion from indirect measurements, via reaction [12,16,22] and β-decay studies [13,15,17]. The β-decay of 23 Al populates excited states of 23 Mg that can decay by both proton and γ emission. Proton emission following the β-decay of 23 Al was reported first by Gough et al in Ref.…”