14-16 November 2011
IPN Orsay
Europe/Paris timezone


15 Nov 2011, 16:00
Auditorium Irène Joliot-Curie (IPN Orsay)

Auditorium Irène Joliot-Curie

IPN Orsay


Anabel Morales Lopez (INFN-Milano)


The study of the beta-decay process in heavy neutron-rich systems is of main importance to probe the nuclear models used in r-process calculations. Experimental evidence is particularly interesting in nuclei approaching the waiting point A~195, since the r-process nuclei are still inaccessible in laboratory and the beta-decay models used to extrapolate their properties show strong discrepancies in their predictions [1,2]. Here we present the first results of an experiment focused on the investigation of the neutron-rich Tl isotopes, carried out within the “Stopped beam Campaign” of the RISING collaboration at GSI. The nuclei of interest were produced in fragmentation reactions of a relativistic Uranium beam impinging on a thick Be target. The residues were subsequently identified in the magnetic spectrometer Fragment Separator (FRS) and were finally implanted in the RISING Active Stopper [3]. This device consisted of nine Double Sided Silicon Strip Detectors (DSSSD) that recorded the position and time of implantations and beta-electrons. The characteristic gamma-ray transitions of the daughter Pb nuclei were registered using the RISING gamma-ray spectrometer [4], placed in close isotropic geometry around the Active Stopper. The event-by-event position and time correlations between implantations and gamma-labeled radioactive electrons allowed us to measure the beta-decay half-lives of 211,212,213Tl, as well as the low-energy structure of their daughter nuclei 211,212,213Pb. The comparison of the new lifetimes with the calculations of the nuclear models proposed to describe the r-process provides a significant experimental constraint to their validity near the third r-process abundance peak, confirming previous half-life measurements near the shell closure N=126 [5-7]. [1] P. Möller et al., Phys. Rev. C 67 (2003) 055802 [2] I.N. Borzov, Phys. Rev C 67 (2003) 025802 [3] R. Kumar et al., Nucl. Instr. Meth. A 598 (2009) 754 [4] S, Pietri et al., Nucl. Instr. Meth B 261 (2007) 1079 [5] T. kurtukian et al., Nucl. Instr. Meth A 589 (2008) 472 [6] N. Alkhomashi et al., Phys. Rev. C 80 (2009) 064308 [7] A.I. Morales, PhD thesis. Universidad de Santiago de Compostela, 2011

Primary author


Dr Andrea Gottardo (INFN-Legnaro) Dr Giovanna Benzoni (INFN-Milano) Dr Jose Javier Valiente-Dobon (INFN-Legnaro) Roberto Nicolini (INFN-Milano)

Presentation Materials