کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5494751 | 1528783 | 2017 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Pygmy and core polarization dipole modes in 206Pb: Connecting nuclear structure to stellar nucleosynthesis
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک هسته ای و انرژی بالا
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
A high-resolution study of the electromagnetic response of 206Pb below the neutron separation energy is performed using a (γâ,γâ²) experiment at the HIγâS facility. Nuclear resonance fluorescence with 100% linearly polarized photon beams is used to measure spins, parities, branching ratios, and decay widths of excited states in 206Pb from 4.9 to 8.1 MeV. The extracted ΣB(E1)â and ΣB(M1)â values for the total electric and magnetic dipole strength below the neutron separation energy are 0.9±0.2e2fm2 and 8.3±2.0μN2, respectively. These measurements are found to be in very good agreement with the predictions from an energy-density functional (EDF) plus quasiparticle phonon model (QPM). Such a detailed theoretical analysis allows to separate the pygmy dipole resonance from both the tail of the giant dipole resonance and multi-phonon excitations. Combined with earlier photonuclear experiments above the neutron separation energy, one extracts a value for the electric dipole polarizability of 206Pb of αD=122±10mb/MeV. When compared to predictions from both the EDF+QPM and accurately calibrated relativistic EDFs, one deduces a range for the neutron-skin thickness of Rskin206=0.12-0.19fm and a corresponding range for the slope of the symmetry energy of L=48-60MeV. This newly obtained information is also used to estimate the Maxwellian-averaged radiative cross section Pb205(n,γ)Pb206 at 30 keV to be Ï=130±25mb. The astrophysical impact of this measurement-on both the s-process in stellar nucleosynthesis and on the equation of state of neutron-rich matter-is discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics Letters B - Volume 773, 10 October 2017, Pages 20-25
Journal: Physics Letters B - Volume 773, 10 October 2017, Pages 20-25
نویسندگان
A.P. Tonchev, N. Tsoneva, C. Bhatia, C.W. Arnold, S. Goriely, S.L. Hammond, J.H. Kelley, E. Kwan, H. Lenske, J. Piekarewicz, R. Raut, G. Rusev, T. Shizuma, W. Tornow,