19F(α, n), (α, p) and22Ne(p, n) and (p, p1γ) reactions near neutron threshold

The reactions19F(α, n), (α, p), (α, α2γ) and22Ne(p, n) and (p, p1γ) have been studied with high resolution around the neutron threshold in23Na. The following resonances have been observed: (α, p0): Eα(lab)=(2 347.0±0.5) keV, (α, p1): Eα(lab)=(2 353.0±0.5) keV, (p, p1γ):E p(lab)=(3 778.0±0.5) KeV and E p(lab)=(3 789.0±0.5) keV. The coupling of these resonances with the neutron channel was investigated. It has been found that none of the ratios of the alpha-particle channel and proton channel partial width to the p1 channel partial width was in agreement with the values expected from a previous measurement of the22Na(n, p0), (n, p1) and (n, α) reactions with thermal neutrons. In none of the excitation functions observed any anomaly around the neutron threshold due to the coupling with the neutron channel was observed. An estimate using the S-matrix theory of nuclear reactions shows that this effect should not exceed 2%. © 1973 Società Italiana di Fisica.