rpProcess and Masses ofN≈Z≈34Nuclides

Abstract

High-precision Penning-trap mass measurements of the N approximately Z approximately 34 nuclides 68Se, 70Se, (70m)Br, and 71Br were performed, reaching experimental uncertainties of 0.5-15 keV. The new and improved mass data together with theoretical Coulomb displacement energies were used as input for rp process network calculations. An increase in the effective lifetime of the waiting point nucleus 68Se was found, and more precise information was obtained on the luminosity during a type I x-ray burst along with the final elemental abundances after the burst.

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

“…On the other hand, the F t value obtained in the second row, F t = 4074 ± 83 s, differs dramatically from the mean F t, pointing to a possible incorrect determination of the Q EC value from the masses measured in the Penning-trap experiment [4]. The Q EC value of this decay is specifically discussed in Ref.…”

“…[2]. In the second line of the table we have determined the F t value for a total transition energy Q EC =10504(15) keV, which was adopted in the last atomic mass evaluation [64] from a Penningtrap mass measurement [4]. In this case the f value has been determined using the LOGFT code available in the National Nuclear Data Center (NNDC) website [65].…”

“…First line, using the QEC from [2,3], the f value quoted in [2] and the experimental t 1/2 and R determined in this work. Second line, using the QEC value from [4,64] and the f value determined using the LOGFT code available in the NNDC website [65]. Transition-dependent radiative and nuclear corrections are taken from Ref.…”

“…It is worth also noting that most of these nuclei are on the pathway of the rp-process of stellar nucleosynthesis [4,34,35] and some of them, as 68 Se and 72 Kr, are important waiting-points defining the time scale of the process. Here, shape coexistence and mixing are crucial to determine the shape of the β-strength distribution and, hence, the stellar β-decay rates.…”

“…The superallowed β decay of 70 Br has been excluded from this compilation due to conflicting experimental values for the Q EC decay energy [3,4]. On top of this, the currently adopted half-life is only known to a precision of ∼ 10 parts in a thousand and the superallowed 0 + → 0 + branching ratio has not been measured yet [2].…”