1. Roger Caballero-Folch (DFEN –UPC) València, 15 de juliol de 2013 β-decay half-lives and β- delayed neutron emission measurements for r-process nucleosynthesis

2. S410 experiment collaboration: R. Caballero-Folch, C. Domingo-Pardo, G. Cortes, J.L. Taín, J. Agramunt, A. Algora, F. Ameil, Y. Ayyad, J. Benlliure, M. Bowry, F. Calviño, D. Cano-Ott, T. Davinson, I. Dillmann, A. Estrade, A. Evdokimov, T. Faestermann, F. Farinon, D. Galaviz, A. García-Ríos, H. Geissel, W. Gelletly, R. Gernhäuser, M.B. Gomez-Hornillos, C. Guerrero, M. Heil, C. Hinke, R. Knöbel, I. Kojouharov, J. Kurcewicz, N. Kurz, Y. Litvinov, L. Maier, J. Marganiec, M. Marta, T. Martnez, F. Montes, I. Mukha, D.R. Napoli, C. Nociforo, C. Paradela, S. Pietri, Zs. Podolyak, A. Prochazka, S. Rice, A. Riego, B. Rubio, H. Schaner, C. Scheidenberger, K. Smith, E. Sokol, K. Steiger, B. Sun, M. Takechi, D. Testov, H. Weick, E. Wilson, J.S. Wineld, R. Wood, P. Woods, and A. Yeremin.

3. Astrophysics motivation Contents Ongoing analysis and preliminary results slide 1 of 14 Experimental setup at GSI-FRS facility Summary and outlook Detection System: SIMBA & BELEN detector

4. Motivation: nucleosynthesis beyond Fe in the r-process path Understanding of A=195 peak in the r-process abundance pattern. The Astr. Jour., 579 (2002), H. Schatz et al. Proc. CGS-13 (2009), G. Martinez-Pinedo Neutron number N Region of interest in this study R-process calculations rely on theoretical predictions (QRPA & FRDM), with remarkable discrepancies and large uncertainties far of stability. Goal: Experimental determination of half lives and neutron branchings of several exotic nuclei in the neutron rich region beyond N=126 slide 2 of 14

5. t 1/2 x 0.1 Nuclear data for the Pt-peak formation: half-lives NPA VI, Lisbon, 20-24 May 2013 N=126 known t 1/2 Slide 3 of 14 FRDM Model

6. Experiment at GSI – FRS facility. 238 U fragmentation beam. Large intensity (2x10 9 ions/pulse) & high-energy (1 GeV/u) for 238 U beams The detection system is based on a stack of SSSD- and DSSD-detectors for measuring ion-implants and beta-decays (SIMBA). Implants-region was surrounded by the 4π neutron detector BELEN. SIMBA + BELEN Tracking detectors: particle ID on an event-by-event basis. SIMBA: Implats & β decays BELEN: Neutrons slide 4 of 14 Plenary talk K-H Langanke

7. Implantation, β decay & neutron detection: SIMBA + BELEN The Beta dELayEd Neutron (BELEN) detector, based in 3 He counters embedded in a polyethylene matrix, located around Silicon IMplantation Beta Absorber (SIMBA). Tracking: (X,Y) Implants  - absorber Beam Implantation area PhD thesis C. Hinke, TUM (2010) Diploma thesis K. Steiger, TUM (2009) BELEN efficiency was about 40% (checked experimentally) slide 5 of 14 Silicon striped detectors (SSSD’s and DSSD’s)

8. Noise Neutron signal Neutron detection 3He counters as detector The detection of the neutron is based on an indirect method: the detection of the products of the reaction of the neutron with 3 He counters: 3 He + n  3 H + 1 H + 765 keV Other reactions: 10 B + n → 7 Li* + 4 He + 2310 keV 7 Li* → 7 Li + 480 keV Ion beam n n n Polyethylene moderator Proportional 3 He counter Silicon β decay detector slide 6 of 14

9. Tests and experiments with BELEN detector Neutron number N GSI:S410 “Measurement of β-delayed neutrons around the 3 rd r-process peak” C. Domingo- Pardo et al. PERFORMED, September 2011 GSI: S323 “Beta-decay of very neutron-rich Rh, Pd, Ag nuclei including the r- process waiting point 128 Pd”. F. Montes et al. PERFORMED, September 2011 Z=28, N=50; JYFL (2009, 2010 & 2013) I162 “Delayed neutron measurements for advanced reactor technologies and astrophysics” JL Taín JYFL. Expected 2013 B.Gomez-Hornillos et al. NIM in progress (2009 exp) Z=50, N=82 Background measurements at GSI (2010) and LSC Canfranc (2011) D.Jordan et al. Astr.Phys Vol.42, Feb 2013, p.1–6 slide 7 of 14

10. Isotopes of Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn and Fr identified Isomer tagging was used for Z identification and two centred settings on 211 Hg and 215 Tl were measured during 4.5 days. The implantation area was optimized for Hg and Tl region where good resolution has been obtained. slide 8 of 14

11. Isotopes of Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn and Fr identified Isomer tagging was used for Z identification and two centred settings on 211 Hg and 215 Tl were measured during 4.5 days. The implantation area was optimized for Hg and Tl region where good resolution has been obtained. slide 8 of 14

12. Good statistics implantation for 208-211 Hg, 211-215 Tl and 214-218 Pb Implants on the high segmented layers of SIMBA detector slide 9 of 14

13. Data available and data expected to obtain slide 10 of 14 http://www.nndc.bnl.govhttp://www.nndc.bnl.gov 209 Hg t 1/2 = 36.5(+/-7.5) s G.Benzoni-A.I.Morales et al, Ph.Lett.B 715 (2012) 211 Tl t 1/2 = 88 ( +46 -29 ) s 212 Tl t 1/2 = 96 ( +42 -38 ) s Possible evaluation of more nuclei implanted implanted in other layers. 211-213/214-215 Tl Implanted in ROI with enough statistics: 208-211 Hg, 211-215 Tl, 214-218 Pb Other implants of 212-213 Hg, 216 Tl, 219 Pb, and 202-204 Pt, 203-208 Au, 217-221 Bi 208-209/210-211 Hg 214-215/216-218 Pb

14. Nuclear data for the Pt-peak formation: state of the art How theoretical models compare with experiment? No experimental information along N=126 region nuclei Only possibility is to benchmark the performance of models in the neighbourhood  It seems that nuclear models tend to overestimate the b-decay half-live at N 126… T. Kurtukian-Nieto et al., arXiv:0711.0101v1 J.Benlliure et al. NPA-V, 2012 G.Benzoni et al., Phys.Lett. B 715 (2012) N = 126 slide 12 of 14

15. Implant – beta correlation studies slide 11 of 14 Several methods of analysis for implant-beta correlation are being performed due to the complex background and statistics.

16. slide 13 of 14 PRELIMINARY implant – beta - neutron correlations 209Hg BELEN Efficiency ~40%

17. slide 13 of 14 PRELIMINARY implant – beta - neutron correlations 211Tl Integral 10 BELEN Efficiency ~40%

18. slide 13 of 14 PRELIMINARY implant – beta - neutron correlations 212Tl Integral 24 BELEN Efficiency ~40%

19. slide 13 of 14 PRELIMINARY implant – beta - neutron correlations 213Tl Integral 12 BELEN Efficiency ~40%

20. Summary and outlook - Several species of neutron rich heavy nuclei have been produced and identified in the Hg/Tl/Pb region, beyond the shell closure N=126. -Correlation methods in order to obtain the half-lives are being studied by implant-beta analysis of signals at DSSD detectors with numerical methods and specific techniques. - In order to obtain final results, we need to improve several aspects in our data-analysis (simulation, statistical comparator, spatial correlations, time-correlations, etc). - The analysis of β-delayed neutron emission probabilities is ongoing. -We plan to measure a large amount of neutron-rich nuclei in a campaign at the RIB facility of RIKEN (Japan). slide 14 of 14

21. Universitat Politècnica de Catalunya (UPC) Institut de Física Corpuscular de València (IFIC) Helmholtzzentrum für Schwerionenforschung GmbH (GSI) NSCL, Michigan State University (MSU-USA) CIEMAT (Madrid) Universidade de Santigo de Compostela (USC) Department of Physics, University of Surrey (UK) CFNUL Universidade de Lisboa (Portugal) School of Physics & Astronomy, U. Edinburgh (UK) Department of Physics, University of Liverpool (UK) STFC, Daresbury Laboratory (UK) Laboratori Nazionali di Legnaro, INFN (Italy) Flerov Laboratory, JINR, Dubna (Russia) CENBG, Université Bordeaux (France) et al. Work supported by the Spanish Ministry of Economy and Competitivity under contract FPA 2011-28770-C03-03 Contact: roger.caballero@upc.edu S410 experiment collaboration