The Nubase evaluation of nuclear and decay properties

Abstract

This paper presents the NUBASE evaluation of nuclear and decay properties of nuclides in their ground-and isomeric-states. All nuclides for which some experimental information is known are considered. NUBASE uses extensively the information given by the "Evaluated Nuclear Structure Data Files" and includes the masses from the "Atomic Mass Evaluation" (AME, second part of this issue). But it also includes information from recent literature and is meant to cover all experimental data along with their references. In case no experimental data is available, trends in the systematics of neighboring nuclides have been used, whenever possible, to derive estimated values (labeled in the database as non-experimental). Adopted procedures and policies are presented.

Theoretical mean-field and experimental occupation probabilities in the double-βdecay systemGe76toMoreno1, Guerra2, Sarriguren3 et al. 2010Phys. Rev. C14160View full textAdd to dashboardCite

“…Because the parameters of the Skyrme interactions are fitted to reproduce these bulk properties in a given set of nuclei, the modification of one of them without an overall refitting of the rest may result in unrealistic values of those bulk properties. Notwithstanding the preceding, when comparing with the experimental binding energies [22] of 661.6 MeV for 76 Ge and 662.07 MeV for 76 Se we get a 0.5% underestimation in the calculation with the usual Sk3 force and a 2% overestimation in the calculation with the Sk3 ν force. Concerning the charge radii, the HF(Sk3) + BCS results are 4.12 fm for 76 Ge and 4.17 fm for 76 Se, whereas with increased spin-orbit strength one gets 4.09 fm for 76 Ge and 4.14 fm for 76 Se, which actually agree better with the experimental values of 4.08 fm for 76 Ge and of 4.14 fm for 76 Se [11].…”

Dirac-Hartree-Bogoliubov approximation for finite nuclei with blocking

“…The results are labled by (DHB+BCS) in figures (3)- (3) and are compared to the experimental results of Ref. [8]. We have also calculated the α-decay chain of of the new superheavy element 277 112 [9] within the blocked+DHB formalism.…”

“…The results, compared to those of a nonrelativistic Hartree-Fock-Bogoliubov approach, which considers a Gogny force (HFB+Gogny), and also to the experimental data of Ref. [8], are shown in Table 1. As can be seen, the results are very promising.…”

On the possibility of enhanced fission stability for broken-pair excitations

“…It decays largely by γ-ray emission, but two delayed-fission events have been detected [5], indicating a partial fission half-life ∼ 10 −3 s, albeit with large experimental uncertainty. Although argued [5] to be substantially inhibited compared to what might be expected at that excitation energy, the partial fission half-life is anyway much shorter than the ground-state partial fission half-life of 10 4 s [1], suggesting that the high-K isomer in 256 Fm fissions much more readily than the ground state. This is very different to the indications for high-K isomers in the second well of actinide nuclei [6].…”

“…While the authors estimate that fission from the isomer is inhibited by a factor of several hundred [12], the 20 minute partial fission half-life of the isomer is still much less than the 8 hours of the ground state [1].…”