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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. Roger Caballero-Folch (DFEN –UPC ) València, 15 de juliol de 2013. S410 experiment collaboration :

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Roger Caballero-Folch (DFEN –UPC ) València, 15 de juliol de 2013

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  1. β-decayhalf-lives and β-delayedneutronemissionmeasurements for r-processnucleosynthesis Roger Caballero-Folch (DFEN –UPC) València, 15 de juliol de 2013

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

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

  5. Nuclear data forthe Pt-peakformation: half-lives N=126 known t1/2 t1/2 x 0.1 FRDM Model Slide 3 of 14 NPA VI, Lisbon, 20-24 May 2013

  6. Experiment at GSI – FRS facility. 238U fragmentation beam. Large intensity (2x109 ions/pulse) & high-energy (1 GeV/u) for 238U beams SIMBA + BELEN Tracking detectors: particle ID on anevent-by-event basis. SIMBA: Implats & βdecays BELEN: Neutrons PlenarytalkK-HLanganke 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. slide 4 of 14

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

  8. 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 3He counters: • 3He + n 3H + 1H + 765 keV • Other reactions: • 10B + n → 7Li* + 4He + 2310 keV • 7Li* → 7Li + 480 keV Noise Neutron signal Polyethylene moderator n n Proportional 3He counter n Ion beam Silicon β decay detector slide 6 of 14

  9. Tests and experiments with BELEN detector GSI:S410 “Measurement of β-delayed neutrons around the 3rdr-processpeak” 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 128Pd”. F. Montes et al. • PERFORMED, • September 2011 Z=50, N=82 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) Background measurements at GSI (2010) and LSC Canfranc (2011) D.Jordan et al. Astr.Phys Vol.42,Feb 2013, p.1–6 Neutron number N 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 211Hg and 215Tl 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 211Hg and 215Tl 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 208-211Hg, 211-215Tl and 214-218Pb Implants on the high segmented layers of SIMBA detector slide 9 of 14

  13. Data available and data expected to obtain Implanted in ROI withenoughstatistics: 208-211Hg, 211-215Tl,214-218Pb Other implants of 212-213Hg, 216Tl, 219Pb, and 202-204Pt,203-208Au, 217-221Bi 214-215/216-218Pb 211-213/214-215Tl 208-209/210-211Hg Possible evaluation of morenucleiimplantedimplanted in otherlayers. http://www.nndc.bnl.gov209Hgt1/2 = 36.5(+/-7.5) s G.Benzoni-A.I.Morales et al, Ph.Lett.B 715 (2012) 211Tl t1/2 = 88 (+46-29) s 212Tl t1/2 = 96 (+42-38) s slide 10 of 14

  14. Nuclear data forthe Pt-peakformation: state of the art • Howtheoreticalmodels compare withexperiment? • No experimental informationalong N=126 regionnuclei • Onlypossibilityistobenchmarkthe performance of models in theneighbourhood 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)  Itseemsthat nuclear modelstendtooverestimatethe b-decayhalf-live at N<126 and tounderestimateitfor N>126… slide 12 of 14

  15. Implant – beta correlation studies Severalmethods of analysis for implant-betacorrelationarebeingperformeddue to the complex background and statistics. slide 11 of 14

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

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

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

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

  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. S410 experiment collaboration UniversitatPolitècnica de Catalunya (UPC) Institut de Física Corpuscular de València (IFIC) HelmholtzzentrumfürSchwerionenforschung 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) LaboratoriNazionalidiLegnaro, INFN (Italy) Flerov Laboratory, JINR, Dubna (Russia) CENBG, Université Bordeaux (France) et al. Contact: roger.caballero@upc.edu WorksupportedbytheSpanishMinistry of Economy and Competitivityundercontract FPA 2011-28770-C03-03

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