First direct measurement of Cu59(p,α)Ni56 : A step towards constraining the Ni-Cu cycle in the cosmos

Charged-particle optical potentials proved by first direct measurement of 59Cu(p,alpha)56Ni reaction

“…Lastly, even the level scheme above the 2.701 MeV first excited state of the residual double-magic nucleus 56 Ni does not matter, the feeding of this state being only ∼4.4% of calculated (p, α) reaction cross section while the rest goes to g.s., in close agreement with experimental evidence [1]. Within the above discussion the nucleon optical potential of Koning and Delaroche [17] was involved as a first option of actual model analyses [1,3,4,16]. The consistent parameter set established using independently measured data as proton reaction σ R and (p, n) reaction cross sections [4], and validated by analysis of (p, γ) and even (p, α) reaction cross sections [3,4] proved however a local OMP of Saini et al [18] as a better option for Cu stable isotopes.…”

“…Similar changes are corresponding to the whole range of NLD parameters for compound nucleus 60 Zn, the related (p, γ) reaction cross sections being by more than two orders of magnitude smaller than the (p, α) reaction cross section. Lastly, even the level scheme above the 2.701 MeV first excited state of the residual double-magic nucleus 56 Ni does not matter, the feeding of this state being only ∼4.4% of calculated (p, α) reaction cross section while the rest goes to g.s., in close agreement with experimental evidence [1]. Within the above discussion the nucleon optical potential of Koning and Delaroche [17] was involved as a first option of actual model analyses [1,3,4,16].…”

“…Model Analysis. Because the OMP [2] was basically involved at once with consistent parameter sets already validated by analysis of other independent data which are * Electronic address: vlad.avrigeanu@nipne.ro distinct from α-induced reaction or α-emission cross sections, we show hereafter the results of a similar analysis for 59 Cu(p, α) 56 Ni reaction cross section around centerof-mass energy of 6 MeV [1]. Actually the same parameter set already considered within the (p, α) reaction analysis on Cu stable isotopes too, with details given in Sec.…”

“…Introduction. First direct measurement of 59 Cu(p, α) 56 Ni reaction cross section at a center-of-mass energy of 6 MeV [1], of foremost importance to understand the Ni-Cu cycle in the cosmos, has also been essential to test the validity of the Hauser-Feshbach (HF) statistical model predictions. It was thus found that all recent alphaparticle optical model potentials (OMPs), beyond only a marginal influence of the other HF parameters, overestimate the experimental result by a factor of ∼2.…”

“…FIG.1:(Color online) Comparison of 59 Cu(p, α)56 Ni reaction cross sections measured[1], TENDL evaluated[15] (⋆) and TALYS default-calculated values[16] (dotted curve), as well as results of using the α-particle OMP of Ref [2]. and proton OMP of (i) Koning and Delaroche[17] (dash-dot-dotted curve), (ii) Saini et al[18] (dash-dotted curve), (iii) also using the (N − Z)/A dependence of the real-potential depth and surface-imaginary potential diffuseness (dashed curve), and (iv) the anomalous imaginary-potential depth either limits of 1-2 MeV[19] (lower cross-section uncertainty band) or (v) the energy dependence W (E) of Ref [20].…”