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Kaori Fujii (INFN Trieste)

Status of the 186,187,188 Os (n, γ ) analysis. n_TOF Collaboration Annual Meeting at Bari. Kaori Fujii (INFN Trieste) M.Mosconi, F K ä ppeler (FZK) A.Mengoni (IAEA,CERN)

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Kaori Fujii (INFN Trieste)

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  1. Status of the 186,187,188Os (n,γ) analysis n_TOF Collaboration Annual Meeting at Bari Kaori Fujii (INFN Trieste) M.Mosconi, F Käppeler (FZK) A.Mengoni (IAEA,CERN) P.M.Milazzo (INFN Trieste) nTOF meeting at Bari, Os analysis

  2. RRR (resolved resonance region) Resonance parameters analysis (SAMMY) → Statistical parameters → Hauser-Feshbach theory calculation (TALYS) RRR + URR (un-RRR) capture cross section → MACS (Maxwellian averaged cross section)M.Mosconi →application (Re/Os clock) Os data analysis nTOF meeting at Bari, Os analysis

  3. Cross section 187Os 186Os Cross section (b) nTOF : 186,187,188 Os Segawa et al. : 186,187,189 Os (Phy.Rev.C76, 022802(R) 2007) En (keV) nTOF meeting at Bari, Os analysis

  4. Resonance parameters nTOF Cross section186Os (I=0) En max ~3.3 keV (N = 126 resonances) 187Os (I=1/2) En max ~ 2.0 keV (N = 313resonances) 188Os (I=0) En max ~ 5.0 keV (N = 115 resonances) Analyzed with SAMMY Reference Atlas of Neutron Cross Resonances Mughabghab 2006 186Os En max ~ 3.3 keV (N = 123 resonances) 187Os En max ~ 1.0 keV (N = 177 resonances) 188Os En max ~ 5.0 keV (N = 101 resonances) nTOF meeting at Bari, Os analysis

  5. Statistical parameters Preliminary ND2007 Γγ free Γn fixed nTOF Γγ fixed Γn free Winters 1986 Mughabghab 2006 nTOF meeting at Bari, Os analysis

  6. Distribution of gΓn0/ <gΓn0> Γγ free Γn fixed Γγ fixed Γn free nTOF meeting at Bari, Os analysis

  7. Maxwellian averaged cross section MACS (mb) kT (keV) n_TOF, Bao n_TOF 188Os MACS is small M.Mosconi (FZK) nTOF meeting at Bari, Os analysis

  8. Nuclear cosmochronology Application : Re/Os clock Nucleosynthesis Big bang Δ = ? 4.5 Gyr Galaxy Solar system Present We are here! Total age of the universe: ta = Δ + 4.5 Gyr Need to know Δ : Nucleosynthesis time duration → nuclear cosmochronometers, Re/Os clock nTOF meeting at Bari, Os analysis

  9. Z s- only 186Os 187Os 188Os 189Os 76 β 185Re 187Re 75 r-process s-process N 110 111 112 113 Re/Os clock Abundance of 187Osat the time of the formation of the solar system (just after Nucleosynthesis) Nucleosynthesis N187Os=Nβ187Os+ Ns-process187Os =Nβ187Os + σ*186Os/ σ*187Os Ns186Os •187Os and 186Os only s-process Their s-abundances (σ* N = const.) σ* : stellar (n, γ) cross sections Proposed by Clayton in 1964 • 187Re β-decay (t½ =~ 40 Gyr) nTOF meeting at Bari, Os analysis

  10. WE HAVE cross sections of 186,187Os (ground state) → MACS BUT at the stellar condition (kT = 30 keV) 187Os : Not only ground state (~30%), But also excited states (9.75 keV (~45%), 73.33 keV...) Stellar cross section = SEF × MACS lab (ground state) SEF:Stellar Enhancement Factor 1st gs Re/Os clock difficulty Theory nTOF meeting at Bari, Os analysis

  11. Capture Cross section - nTOF data - TALYS Cross section (b) En (keV) HF theory calculation 186Os 187Os Calculation of cross sections under stellar condition -----> MACS stellar 188Os Preliminary nTOF meeting at Bari, Os analysis

  12. Theoretical calculation (187Os) SEF = MACSst / MACSgs Calculated by TALYS Preliminary nTOF meeting at Bari, Os analysis

  13. Calculation of the age (1) 187Os cosmoradiogenic abundance 187Os s-process abundance 187Re β-decay (λβ = ln2 /t½ ) t½ : 41.2 ± 1.12 Gyr : Galeazzi (2000) 187Re r-process ( rate ≡ exp(λrt) 1. Sudden (λr →∞) : ~ λβ t 2. Uniform (λr →0) : ~ λβ t/ 2 3. Fowler model (λr =1/0.43 t) : Faestermann (1998) nTOF data = 0.126 Preliminary nTOF meeting at Bari, Os analysis

  14. Calculation of the age (2) n_TOF Nucleosynthesis time duration Δ : 10.5 Gyr The age of the universe ta 15.0 ± 1.4 Gyr (total) ± 0.8 Gyr (σ, our data) ± 1.0 Gyr (abundance) ± 0.6 Gyr(187Re β-decay rate) • sudden • Fowler model • uniform 10.5 Gyr 10.48 Gyr Preliminary Time duration (Gyr) nTOF meeting at Bari, Os analysis

  15. Age of the universe : ta ta(Gyr) nTOF nTOF meeting at Bari, Os analysis Cosmological way Hubble time (WL. Friedman, 2001) WMAP (cosmic microwave) (CL.Bennett, 2001) Astronomical way Globular clusters (DN.Spergel, 1997) Nuclear way Th/U (Dauphas, 2005) Re/Os (nTOF preliminary)

  16. Summary + working progress The age of the universe is estimated. Preliminary • Points to fix Resonance parameters (SAMMY) Statistical parameters • Application to cosmochronometer Theoretical calculation precise GCE model nTOF meeting at Bari, Os analysis

  17. <Γγ>distribution Γn Fixed ND2007 nTOF meeting at Bari, Os analysis

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