Measurement of alpha‐widths in 16O relevant to astrophysics

Several different α‐transfer reactions, 12C→16O, have been studied at high bombarding energies with magnetic spectrometers. Line‐widths, α‐spectroscopic factors, Sα, and reduced α‐widths, γα2 and ϑα2, have been determined for levels in 16O, including several of importance in astrophysics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87457/2/752_1.pd

Reaction dependence of nuclear decay linewidths

Various light- and heavy-ion reactions, 20 E 8Be*(2 + , 2.9 MeV) and 16O*(1-, 9.6 MeV). Although slight differences (R) are self-consistent and indicate little if any reaction dependence (R by 20 % or more, however, and thus care must be taken in comparing decay widths inferred from nuclear reactions with those from scattering resonances. Reduced formal [alpha]-decay widths of [gamma][lambda]2 = 680 +/- 100 keV (s = 4.8 fm) and [gamma][lambda]2 = 350 +/- 50 keV(s = 5.4 fm), corresponding to [theta][lambda]2 = 0.50 and [theta][lambda]2 = 0.49 are deduced for 8Be*(2 + , 2.9 MeV) and 16O*(1-, 9.6 MeV) using the nuclear-reaction [Gamma]R values and a particular set of [alpha]-nucleus potentials.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24278/1/0000544.pd

Two-proton events in the 17F(p,2p)16O reaction

In a recent experimental study (Gomez del Campo et al, PRL 86, 43 (2001)) of the reaction 17F(p,2p)16O, two-proton events were measured from excitations near a 1-, E*=6.15 MeV state in 18Ne. We calculate by means of R-matrix theory the resonant two-proton production cross section and branching ratios. We conclude that it is unlikely that two-proton production via population of the 1- state is sufficient to explain the observed two-proton events. Alternative sources of such events are discussed.Comment: 4 pages, 4 figures. Resubmission to Physical Review C (first received 6 March 2001

An above-barrier narrow resonance in ¹⁵F

Intense and purified radioactive beam of post-accelerated $^{14}$O was used to study the low-lying states in the unbound $^{15}$F nucleus. Exploiting resonant elastic scattering in inverse kinematics with a thick target, the second excited state, a resonance at E$\_R$=4.757(6)(10)~MeV with a width of $\Gamma$=36(5)(14)~keV was measured for the first time with high precision. The structure of this narrow above-barrier state in a nucleus located two neutrons beyond the proton drip line was investigated using the Gamow Shell Model in the coupled channel representation with a $^{12}$C core and three valence protons. It is found that it is an almost pure wave function of two quasi-bound protons in the $2s\_{1/2}$ shell.Comment: 8 pages, 2 figures, 1 table, Submitted to Phys. Lett.