Measurements of keV-Neutron Capture Cross Sections and Capture Gamma-Ray Spectra of 117,119Sn

Nishiyama, Jun; Igashira, M.; Ohsaki, T.; Kim, Guinyun; Chung, Won-Chung; Tae-Ik, RO

doi:10.3327/jnst.45.352

Cited by 10 publications

(16 citation statements)

References 15 publications

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“…Note that in Fig.10, we do not compare our results with the available 207 Pb(n,γ) 208 Pb cross section [40,41] because these low-energy data (two points) are in the discrete resonance energy region. We see a large difference [34,36,37] between the results obtained with the GSM and other NLD models (EMPIRE-specific and HFB plus combinatorial), namely, the GSM (n,γ) cross section is about one order of magnitude larger for neutrons up to energies of 2 MeV and 10 MeV for the compound 132 Sn and 208 Pb, respectively. There is no noticeable difference between the results obtained with phenomenological EMPIREspecific and microscopic HFB plus combinatorial NLD models.…”

Section: Neutron Radiative Capturementioning

confidence: 99%

“…CAPTURE GAMMA-RAY SPECTRA In Ref. [37], neutron capture gamma-ray spectra of 117 Sn and 119 Sn have been measured. With the use of EMPIRE and in order to compare them with theoretical predictions, we divide our results for gamma-ray spectra in mb/MeV units by the capture cross sections at E n = 52 keV and E n =570 keV for 119 Sn (Fig.…”

Section: Neutron Radiative Capturementioning

confidence: 99%

“…In other words, we did not consider here the incident neutron energy spectra and took the neutron average energy of 52 keV given by the authors of Ref. [37]. The neutron cross sections are calculated with EMPIRE for three theoretical PSF models, EGLO, QRPA and QTBA.…”

Section: Neutron Radiative Capturementioning

confidence: 99%

“…The neutron cross sections are calculated with EMPIRE for three theoretical PSF models, EGLO, QRPA and QTBA. The comparison with experiment [37] is presented for two NLD models, namely the GSM (Fig. 11) and the microscopic HFB plus combinatorial model [32] (Fig.…”

Section: Neutron Radiative Capturementioning

confidence: 99%

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On microscopic theory of radiative nuclear reaction characteristics

et al. 2016

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A survey of some results in the modern microscopic theory of properties of nuclear reactions with gamma-rays is given. First of all, we discuss the impact of phonon coupling (PC) on the photon strength function (PSF) because it represents the most natural physical source of additional strength found for Sn isotopes in recent experiments that could not be explained within the standard HFB+QRPA approach. The self-consistent version of the Extended Theory of Finite Fermi Systems in the Quasiparticle Time Blocking Approximation, or simply QTBA, is applied. It uses the HFB mean field and includes both the QRPA and PC effects on the basis of the SLy4 Skyrme force. With our microscopic E1 PSFs, the following properties have been calculated for many stable and unstable even-even semi-magic Sn and Ni isotopes as well as for double-magic 132 Sn and 208 Pb using the reaction codes EMPIRE and TALYS with several nuclear level density (NLD) models: 1) the neutron capture cross sections, 2) the corresponding neutron capture gamma spectra, 3) the average radiative widths of neutron resonances. In all the properties considered, the PC contribution turned out to be significant, as compared with the standard QRPA one, and necessary to explain the available experimental data. The results with the phenomenological so-called generalized superfluid NLD model turned out to be worse, on the whole, than those obtained with the microscopic HFB+combinatorial NLD model. The very topical question about the M1 resonance contribution to PSFs is also discussed.Finally, we also discuss the modern microscopic NLD models based on the self-consistent HFB method and show their relevance to explain experimental data as compared with the phenomenological models. The use of these self-consistent microscopic approaches is of particular relevance for nuclear astrophysics, but also for the study of double-magic nuclei.

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Section: Neutron Radiative Capturementioning

confidence: 99%

Section: Neutron Radiative Capturementioning

confidence: 99%

Section: Neutron Radiative Capturementioning

confidence: 99%

Section: Neutron Radiative Capturementioning

confidence: 99%

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On microscopic theory of radiative nuclear reaction characteristics

et al. 2016

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“…The picture is approximately the same for widely used quantities 2πΓ γ /D 0 , where D 0 is the average distance between the levels of a compound nucleus. The experimental data are taken from [29][30][31][32].…”

mentioning

confidence: 99%

Microscopic nature of the radiative strength function: Structures, coupling with phonons

2015

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The notion of the radiative strength function was introduced for the description of gamma transitions from highly excited states in a wide energy range near the neutron separation energy [1]. This quantity is necessary for the calculation of all characteristics of radiative processes in nuclei, in particular, the cross sections for radiative capture of a neutron, which is one of the most important reactions in processes of nucleosynthesis and in the calculations of nuclear and nuclear fusion reactors. The generalized radiative strength function, which involves transitions between excited states, is usually used. In this case, the use of the radiative strength function in the calculation of cross sections for radiative processes is based on the Brink-Axel hypothesis [2,3]. According to this hypothesis, the giant dipole resonance (GDR) can be constructed on any excited state and its properties are independent of the nature of this state. Within this hypothesis, which currently is a commonly accepted, mainly justified approximation, the radiative strength function is simply related to the photoabsorption cross section (see below) and to the problems of the pygmy dipole resonance (PDR) (see [4]).The problems of the PDR have attracted significant attention of researchers in "pure" nuclear physics and of specialists in nuclear data in recent years [5][6][7]. This resonance is located in the low energy tail of the GDR, i.e., in a wide region near the nucleon separa tion energy. Although it usually exhausts 1-2% of the Thomas-Reiche-Kuhn sum rule, its role in radiative nuclear processes is very significant [8]. We also emphasize that the characteristics of the PDR in nuclei with a low neutron separation energy (below 3-4 MeV) are strongly different and, consequently, phe nomenological systematics based on data obtained for stable nuclei with a normal separation energy near 8 MeV are inappropriate. In this sense, the phenome nological description is not predictive. For this reason, self consistent microscopic approaches are actively developed. They are much more predictive and pre tend to describe both ground and excited states of all nuclei, except for the lightest, with a set of a few (about ten) universal parameters describing either Skyrme forces or the energy functional [5,6,8].The microscopic nature of the radiative strength function, which is the most important characteristic neces sary for the description of nuclear reactions involving gamma ray photons both in astrophysics and in the the ory of nuclear reactors, has been discussed. It has been shown that, in contrast to phenomenological approaches based on various modifications of the Lorentzian dependence for this function, the microscopic approach gives structures that are due to the effects both within the standard random phase approximation and of coupling with low lying collective excitations (phonons), i.e., beyond the standard random phase approximation. Microscopic calculations of the strength function for several Sn and Ni isotopes have been performed wi...

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Neutron Resonance Parameters for Sn-117 (Tin)

Sukhoruchkin

Soroko

2009

Neutron Resonance Parameters

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Measurements of keV-Neutron Capture Cross Sections and Capture Gamma-Ray Spectra of 117,119Sn

Cited by 10 publications

References 15 publications

On microscopic theory of radiative nuclear reaction characteristics

On microscopic theory of radiative nuclear reaction characteristics

Microscopic nature of the radiative strength function: Structures, coupling with phonons

Neutron Resonance Parameters for Sn-117 (Tin)

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