Enhanced Radiative Strength in the Quasicontinuum ofSn117

Abstract

The radiative strength function of 117Sn has been measured up to the neutron separation energy using the (3He, 3He' gamma) reaction. An increase in the slope of the strength function around E gamma=4.5 MeV indicates the onset of a resonancelike structure, giving a significant enhancement of the radiative strength function compared to standard models in the energy region 4.5<or=E gamma<or=8.0 MeV. For the first time, the functional form of this resonancelike structure has been measured in an odd tin nucleus below neutron threshold in the quasicontinuum region.

Soft structures ofγ-ray strength functions studied with the Oslo method

“…[19] for details. This is shown in is also seen that the standard Lorentzian (SLO) model fits the (γ, x) data very well; however, it is not able to describe neither the shape nor the magnitude of our data below the neutron threshold.…”

“…Further investigations are needed both on the upbend phenomenon and the resonance-like structure of the Sn isotopes. [19], and from (γ, x) photonuclear reactions (red open triangles [20], stars [21], and blue open squares [22]). The sum of the GLO E1 strength and the M1 spin-flip resonance is shown as a solid line.…”

“…In this work we present recent results on the γ-ray strength functions of the nuclei 44,45 Sc [1], 50,51 V [2], 93−98 Mo [3], and 116−119 Sn [4,5].…”

Statistical gamma-ray emission of gold and its astrophysical implications

“…3 the experimental gamma strength is also compared with theoretical models for the IVGDR resonance (generalized Lorentzian model GLO [10]) and for the magnetic spin-flip resonace (stantard Lorentzian model SLO [11]). In absence of an established theoretical prediction for the pygmy resonace a Gaussian distribution is chosen [12]. It is clear that additional terms are needed to fit the low-energy part of the experimental data.…”

A unified understanding of (γ, n) and (n, γ) reactions and direct neutron-multiplicity sorting

“…Based on the Brink hypothesis of the approximate equality of the upward and downward γ SF, one can construct the γ SF by combining (γ ,n), (γ ,γ ) and the Oslo data with the (γ ,n) cross section as absolute normalization. Figures 6 and 7 show thus constructed γ SF for 117 Sn [13] and 74 Ge [15].…”