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Beta strength measurements near to the 3rd r-process peak

Beta strength measurements near to the 3rd r-process peak. (South-west of 208 Pb). Darmstadt-Gatchina-Madrid-Santiago-Surrey- Valencia …. DESPEC TAS. +. AIDA. Jose L. Tain @ IFIC-Valencia. PRESPEC Decay Workshop, Brighton, January 12-13, 2011.

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Beta strength measurements near to the 3rd r-process peak

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  1. Beta strength measurements near to the 3rd r-process peak (South-west of 208Pb) Darmstadt-Gatchina-Madrid-Santiago-Surrey-Valencia… DESPEC TAS + AIDA Jose L. Tain @ IFIC-Valencia PRESPEC Decay Workshop, Brighton, January 12-13, 2011

  2. Beta strength calculations are needed in order to obtain T1/2 and Pn values for most of the nuclei involved in r-process calculations : 0+ Fermi : 1+ Gamow-Teller : 0-,1- Non-unique first forbidden : 2- Unique first forbidden … • The quality of the model calculations is judged by comparison with experimental T1/2 and eventually Pn values in particular for the most neutron rich accessible nuclei, which are however integral quantities • Direct comparison of calculated and measured S provides a more stringent test of the nuclear structure models

  3. Total Absorption Gamma-ray Spectroscopy: • Uses large 4 scintillation detectors,aimingto detect the full -ray cascade rather than individual -rays -decay real TAS spectrum (deconvolution) strength ideal TAS (=100%) Inverse problem MC simulations + know level sch. + statistical model

  4. FF GT “South-west” of 208Pb • “Close” to r-process 3rd abundance peak • Decay dominated by FF transitions • Largely unexplored but accessible at GSI r-process

  5. 200Os (Z=76, N=124) • Borzov, Phys.At.Nucl. (2011) • DF+QRPA • both GT and FF microscopic • no deformation Q = 2.6 MeV (SY) Expected number of levels: Nlev=800 Goriely et al. PRC78(08) 064307

  6. 202Ir (Z=77, N=125) Expected number of levels: Nlev=4.1104 Q = 5.4 MeV (SY)

  7. |2| deformation • Further into the play: deformation Moeller et al., ADNDT59(95)185 (Exp: NuDat)

  8. PRC67(03)055802 : GT+FF ADNDT66(97)131 : GT • Moeller et al. • FRDM+QRPA • FF from Gr.Th. • deformation • exper. Q, Sn T1/2 Pn

  9. DF3: Borzov, Phys.At.Nucl. (2011), FRDM: Moeller et al., PRC67(03)055802 Z=76 Z=77 Z=78 Z=79

  10. J. Benlliure et al., NIC XI, Heidelberg, 2011 • Region accessible with enough statistics (204Au,204,203Pt, 201Ir,…) 208Pb (1GeV/u) + Be (2.5g/cm2) • T. Kurtukian et al., NPA827 (2009) 687c • A.I. Morales, PhD Thesis, U. Santiago, 2011

  11. A.I. Morales, PhD Thesis, U. Santiago, 2011  Q = 2.3 MeV (SY) Q = 5.4 MeV (SY) Nlev=2.7103 Nlev=4.1104

  12. J. Benlliure et al., NIC XI, Heidelberg, 2011 C. Domingo-Pardo et al., Experiment S410

  13. 16 + 1 modules: 151525 cm3 NaI(Tl) + 5” PMT (50% light col.) V= 95 L, M= 351 kg PROTOTYPE RE= 6.8% @662keV t(FWHM) = 4.5 ns Light collection MC simulation Exp. • Half detector will be ordered this year • The rest in 2012

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