$β$-decay half-lives and $β$-delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb and Bi, beyond N=126
Creators: name: Caballero-Folch, R.
name: Domingo-Pardo, C.
name: Agramunt, J.
name: Algora, A.
name: Ameil, F.
name: Ayyad, Y.
name: Benlliure, J.
name: Bowry, M.
name: Calviño, F.
name: Cano-Ott, D.
name: Cortès, G.
name: Davinson, T.
name: Dillmann, I.
name: Estrade, A.
name: Evdokimov, A.
name: Faestermann, T.
name: Farinon, F.
name: Galaviz, D.
name: García, A. R.
name: Geissel, H.
name: Gelletly, W.
name: Gernhäuser, R.
name: Gómez-Hornillos, M. B.
name: Guerrero, C.
name: Heil, M.
name: Hinke, C.
name: Knöbel, R.
name: Kojouharov, I.
name: Kurcewicz, J.
name: Kurz, N.
name: Litvinov, Yu. A.
name: Maier, L.
name: Marganiec, J.
name: Marta, M.
name: Martínez, T.
name: Montes, F.
name: Mukha, I.
name: Napoli, D. R.
name: Nociforo, C.
name: Paradela, C.
name: Pietri, S.
name: Podolyák, Zs.
name: Prochazka, A.
name: Rice, S.
name: Riego, A.
name: Rubio, B.
name: Schaffner, H.
name: Scheidenberger, Ch.
name: Smith, K.
name: Sokol, E.
name: Steiger, K.
name: Sun, B.
name: Taín, J. L.
name: Takechi, M.
name: Testov, D.
name: Weick, H.
name: Wilson, E.
name: Winfield, J. S.
name: Wood, R.
name: Woods, P. J.
name: Yeremin, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: $Background:$ Previous measurements of $β$-delayed neutron emitters comprise around 230 nuclei, spanning from the $^{8}$He up to $^{150}$La. Apart from $^{210}$Tl, with a minuscule branching ratio of 0.007\%, no other neutron emitter is measured yet beyond $A=150$. Therefore new data are needed, particularly in the heavy mass region around N=126, in order to guide theoretical models and to understand the formation of the third r-process peak at $A\sim195$. $Purpose:$ To measure both, $β$-decay half-lives and neutron branching ratios of several neutron-rich Au, Hg, Tl, Pb and Bi isotopes beyond $N=126$. $Method:$ Ions of interest are produced by fragmentation of a $^{238}$U beam, selected and identified via the GSI-FRS fragment separator. A stack of segmented silicon detectors (SIMBA) is used to measure ion-implants and $β$-decays. An array of 30 $^3$He tubes embedded in a polyethylene matrix (BELEN) is used to detect neutrons with high efficiency and selectivity. A self-triggered digital system is employed to acquire data and to enable time-correlations. The latter are analyzed with an analytical model and results for the half-lives and neutron-branching ratios are derived using the binned Maximum-Likelihood method. $Results:$ Twenty new $β$-decay half-lives are reported for $^{204-206}$Au, $^{208-211}$Hg,$^{211-216}$Tl,$^{215-218}$Pb and $^{218-220}$Bi, nine of them for the first time. Neutron emission probabilities are reported for $^{210,211}$Hg and $^{211-216}$Tl. $Conclusions:$ The new $β$-decay half-lives are in good agreement with previous measurements in this region. The measured neutron emission probabilities are comparable or smaller than values predicted by global models like RHB+RQRPA.
description: 17 pages, 21 figures, will be submitted at PRC