Excited levels and isobaric analogue states in55Co investigated with the54Fe(p, ?)55Co reaction

Abstract

The yield curve for the S4Fe(p, 7)~5Co reaction in the energy region Ev= 1.5-2.9 MeV has been recorded and the decay of ten resonances has been investigated. For six of the resonances the strengths have been determined. The angular distributions of the gamma rays have been recorded for four resonances to obtain spins or spin limitations for excited levels. In addition the lifetimes of 10 bound levels were determined with the Doppler Shift Attenuation Method. The isobaric analogues of the ground state and five excited states in 55Fe are discussed.

Mass measurements in the vicinity of the doubly magic waiting pointNi56

“…Fe, 53 Co m , 53,56 Co,55,56,57 Ni,57,58 Cu,and 59,60 Zn have been determined with the JYFLTRAP Penning trap mass spectrometer at IGISOL with a precision of δm/m ≤ 3 × 10 −8 .…”

“…Of the nuclides used as references in the frequency ratio measurements, 56 Ni and 58 Cu, have already been discussed above. Here, we concentrate on other reference nuclides: 56,57 Fe, 55,56 Co, 57,58 Ni, and 59 Cu. Masses of these reference nuclides close to 56 Ni are known with a rather modest precision of 0.6 − 2.1 keV.…”

“…At such points, the process must proceed via much slower beta decay. At 56 Ni, the proton-capture Q value to 57 Cu is quite low and critical for the synthesis of elements heavier than nickel. Namely, the beta-decay half-life of 56 Ni is 6.075(10) days [2], exceeding all normal time scales of x-ray bursts and other places where the rp process could occur.…”

“…Previously, 56 Ni was considered as the end point of the rp process [3], but later it was shown to proceed until the SnSbTe-region [4,5]. For an accurate modeling of this process, the proton-capture Q value for the reaction 56 Ni(p,γ) 57 Cu has to be known precisely. 56 Ni is doubly-magic and therefore, the precise knowledge of its mass and the masses of the neighboring nuclei is important for nuclear structure studies around Z = N = 28.…”

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Masses of 56,57 Fe, 53 Co m , 53,56 Co,55,56,57 Ni,57,58 Cu,and 59,60 Zn have been determined with the JYFLTRAP Penning trap mass spectrometer at IGISOL with a precision of δm/m ≤ 3 × 10 −8 .The QEC values for 53 Co, 55 Ni, 56 Ni, 57 Cu, 58 Cu, and 59 Zn have been measured directly with a typical precision of better than 0.7 keV and Coulomb displacement energies have been determined. The Q values for proton captures on 55 Co, 56 Ni, 58 Cu, and 59 Cu have been measured directly.

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