Single-particle shell strengths near the doubly magic nucleus 56Ni and the 56Ni(p,γ)57Cu reaction rate in explosive astrophysical burning

Abstract

Angle-integrated cross-section measurements of the 56 Ni(d,n) and (d,p) stripping reactions have been performed to determine the single-particle strengths of low-lying excited states in the mirror nuclei pair 57 Cu− 57 Ni situated adjacent to the doubly magic nucleus 56 Ni. The reactions were studied in inverse kinematics utilizing a beam of radioactive 56 Ni ions in conjunction with the GRETINA γ-array. Spectroscopic factors are compared with new shell-model calculations using a full p f model space with the GPFX1A Hamiltonian for the isospin-conserving strong interaction plus Coulomb and charge-dependent Hamiltonians. These results were used to set new constraints on the 56 Ni(p,γ) 57 Cu reaction rate for explosive burning conditions in x-ray bursts, where 56 Ni represents a key waiting point in the astrophysical rp-process.

The Regulated NiCu Cycles with the New 57Cu(p,γ)58Zn Reaction Rate and Its Influence on Type I X-Ray Bursts: the GS 1826–24 Clocked Burster

“…The continuous impact from the correlated influence among these reactions and 59 Cu(p,α) 56 Ni that cycles the reaction flow back to the reaction series in the NiCu cycles since the onset subsequently influences the burst ash composition at the burst-tail end. The mass fraction of 57 Cu in the baseline is lower than the one in the Present ♡ and Present § scenarios because the newly updated 56 Ni(p,γ) 57 Cu by Kahl et al (2019) implemented in Present ♡ and Present § is about up to a factor of 9 higher than the recommended 56 Ni(p,γ) 57 Cu rate from JINA REACLIB v2.2 used in baseline at a temperature region of around 1 GK. Nevertheless, the mass fraction of 58 Zn in the baseline is about a factor of 1.2 higher than the one in the Present § scenario.…”

“…The deduced 57 Cu(p,γ) 58 Zn reaction rate is discussed in detail in Section 3. Using the one-dimensional multizone hydrodynamic KEPLER code (Weaver et al 1978;Woosley et al 2004;Heger et al 2007), we model a set of XRB episodes matched with the GS 1826−24 burster with the newly deduced 57 Cu(p,γ) 58 Zn, Valverde et al (2019) 55 Ni(p,γ) 56 Cu, and Kahl et al (2019) 56 Ni(p,γ) 57 Cu reaction rates. We study the influence of these rates and also investigate the effect of the 56 Ni-waiting-point bypassing matter flow induced by the 55 Ni(p,γ) 56 Cu reaction.…”

Nuclear Data and Experiments for Astrophysics

“…The results were in agreement with a previous ( 3 He, d) study [84], supporting the feasibility of the method. The surrogate technique using (d, n) proton-transfer reactions has been applied to the bottleneck reaction in the nova nucleosynthesis, 30 P(p, γ ) [85], and for the key reaction to bypass the waiting-point nucleus 56 Ni in type I X-ray bursts, 56 Ni(p, γ ) 57 Cu [86].…”

Advancement of Photospheric Radius Expansion and Clocked Type-I X-Ray Burst Models with the New $^{22}$Mg$(α,p)^{25}$Al Reaction Rate Determined at Gamow Energy

“…The nuclear structure information provided from the shell-model calculations covers the Gamow window corresponding to the XRB temperature range. We then take these 59 Cu(p,γ) and 61 Ga(p,γ) rates prior to their publication [57], also the Present 22 Mg(α,p), 14 O(α,p) [58], 23 Al(p,γ) [59], 18 Ne(α,p) [60], 55 Ni(p,γ) [62], 56 Ni(p,γ) [63], 57 Cu(p,γ) [64], 64 Ge(p,γ) [61], and 65 As(p,γ) [61] reaction rates to study the combined influence of these reactions on the GS 1826−24 burst lightcurve profile [4] (see Fig. 7).…”