New calculations of grossβ-decay properties for astrophysical applications: Speeding-up the classicalrprocess

Abstract

Recent compilations of experimental gross ␤-decay properties, i.e., half-lives (T 1/2 ) and neutron-emission probabilities ( P n ), are compared to improved global macroscopic-microscopic model predictions. The model combines calculations within the quasiparticle ͑QP͒ random-phase approximation for the Gamow-Teller ͑GT͒ part with an empirical spreading of the QP strength and the gross theory for the first-forbidden part of ␤ Ϫ decay. Nuclear masses are either taken from the 1995 data compilation of Audi et al., when available, otherwise from the finite-range droplet model. Especially for spherical and neutron-͑sub-͒magic isotopes a considerable improvement compared to our earlier predictions for pure GT decay ͑ADNDT, 1997͒ is observed. T 1/2 and P n values up to the neutron drip line have been used in r-process calculations within the classical ''waiting-point'' approximation. With the new nuclear-physics input, a considerable speeding-up of the r-matter flow is observed, in particular at those r-abundance peaks which are related to magic neutron-shell closures.

Neutrino-driven wind simulations and nucleosynthesis of heavy elements

“…Their impact on the abundances have been studied (see e.g., [47,10,79,80]) by using different theoretical mass models (e.g., FRDM [81], ETFSI [82], Duflo & Zuker [83], HFB-x [84,85]). Beta decay rates [86] control the speed of the r-process and during decay to stability become specially important due to the delayed neutron emission.…”

First measurement of beta decay half-lives in neutron-rich Tl and Bi isotopes

“…The treatment of first forbidden (FF) transitions, found to be significant in particular for nuclei crossing the closed shells and having a neutron excess more than one major shell, is also different in both models. Whereas the FF strength is treated as a smooth background by the FRDM+QRPA [9], and thus included using the macroscopic phenomenological Gross Theory [10], the DF3+cQRPA treats FF decays microscopically, in terms of the reduced multipole operators depending on the space and spin variables [11].…”

The Impact of Theoretical \(\beta \)-Decay Rates on the Production of the r-Process Third Peak

“…We constructed two different reaction networks labeled as MPK03 and FBS13 focusing on β-decay rates around ∼ 126 nuclei. MPK03 is based on [12], widely used decay rates including the effect of FF calculated with the gross theory. Besides, we apply FBS13 rates for N = 124-128 nuclei for the FBS13 network, where all other nuclear rates are the same as the MPK03 network.…”