Evaluation of Total Nuclear Photoabsorption Cross-Sections by the Modified Quasi-Deuteron Model

Terranova, Maria Letizia; Lima, D. A. De; Filho, J.D. Pinheiro

doi:10.1209/0295-5075/9/6/005

Cited by 25 publications

(35 citation statements)

References 12 publications

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“…Figure 6 shows partial photoneutron cross sections obtained in the new measurement in comparison with the TALYS [14] calculation of the giant-dipole resonance (GDR) and quasi-deuteron component [15,16]. The GDR cross section was obtained within the Hartree-Fock-Bogolyubov plus quasiparticle random phase approximation approach on the basis of the D1M Gogny interaction both for the E1 [17] and M1 [18] components.…”

Section: Bi(xn) Datamentioning

confidence: 99%

Photoneutron Reaction Data for Nuclear Physics and Astrophysics

Utsunomiya¹,

Renstrøm²,

Tveten³

et al. 2018

EPJ Web Conf.

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Abstract. We discuss the role of photoneutron reaction data in nuclear physics and astrophysics in conjunction with the Coordinated Research Project of the International Atomic Energy Agency with the code F41032 (IAEA-CRP F41032). PHOENIX Collaboration for the IAEA-CRP F41032The In this collaboration, we are measuring (,xn) cross sections with x=1-4 for the first compilation (photonuclear data) and (,1n) cross sections near oneneutron threshold for the second compilation (photon strength functions). A list of nuclei to be measured in the PHOENIX Collaboration is given in Table 1. We provide (,xn) cross section data to resolve the long-standing discrepancy between the Livermore and Saclay data of partial photoneutron cross sections. In many cases, Saclay provided larger cross sections for (,1n) reactions than Livermore and vice versa for (,2n) reactions [2]. The ratio of the Saclay data to the Livermore data of integrated total cross sections, Rint  S int / L int , varies from 0.65 to 1.35 over 19 nuclei from 51 V to 238 U. As shown in Fig. 1, the ratio for

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Section: Bi(xn) Datamentioning

confidence: 99%

Photoneutron Reaction Data for Nuclear Physics and Astrophysics

Utsunomiya¹,

Renstrøm²,

Tveten³

et al. 2018

EPJ Web Conf.

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“…In the decades following Levinger's original work there were few compilations of the photonuclear data and systematic evaluations of the Levinger constant (see e.g. [10] and references therein). It was also found that 2-body short range correlations captured so well by the quasi-deuteron model plays an important role in analyzing hard nuclear electron scattering experiments, see e.g.…”

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confidence: 99%

“…Consequently we shall concentrate on the E1 transition cross-section, which in principle can be extracted from the angular distribution of the emitted pn pair. The experimental evaluation of Levinger's constant [10] is than used to extract the proton-neutron contact.…”

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confidence: 99%

“…Experimental evaluation of the nuclear neutron-proton contact -At this point we would like to extract the nuclear neutron-proton contact from the experimental photonuclear data. To this end we use an analysis of the Levinger constant made by Terranova et al [10], who evaluated the Levinger constant L for 14 nuclei along the periodic table, from lithium to uranium, using various photonuclear experiments [22][23][24][25]. In order to include low energy data Terranova et al have used in their analysis the modified quasi-deuteron model [26], taking into account the Pauli blocking.…”

mentioning

confidence: 99%

“…[24]. Adapted with changes from [10]. The blue line shows the averaged value L = 5.50, and the gray band its error.…”

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Nuclear Neutron-Proton Contact and the Photoabsorption Cross Section

2015

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The nuclear neutron-proton contact is introduced, generalizing Tan's work, and evaluated from medium energy nuclear photodisintegration experiments. To this end we reformulate the quasideuteron model of nuclear photodisintegration and establish the bridge between the Levinger constant and the contact. Using experimental evaluations of Levinger's constant we extract the value of the neutron-proton contact in finite nuclei and in symmetric nuclear matter. Assuming isospin symmetry we propose to evaluate the neutron-neutron contact through measurement of photonuclear spin correlated neutron-proton pairs.PACS numbers: 05.30.Fk, Introduction -Considering a system of two-component fermions interacting via a short range interaction, Tan [1, 2] has established a series of relations between the amplitude of the high-momentum tail of the momentum distribution n σ (k), where σ is the spin, and the properties of the system, such as the energy, pair correlations and pressure. These relations, commonly known as the "Tan relations", are expressed through a new variable the "Contact" C = lim k→∞ k 4 n σ (k). The contact, being a state variable depends on the density of the system (usually expressed through the Fermi momentum k F ), its temperature, composition, and its thermodynamic state. The Tan relations are universal, they hold for few-body as well as for many-body systems, for ground state and for finite temperature, for normal state but also for superfluid state. Their validity range depends on the interparticle distance d ∝ 1/k F and the magnitude of the scattering length being both much larger than the potential range, usually characterized by the effective range r eff .The theoretical discovery of the Tan relations has led to a concentrated experimental effort to measure and verify them in ultracold atomic systems, where the scattering length as well as the density can be controlled. These efforts have led to experimental verification of Tan's relations in fermionic 40 K [3, 4] and 6 Li [5][6][7] systems. It was also found that the measured value of the contact, as function of (k F a) −1 along the BCS-BEC crossover, is in accordance with the theoretical predictions of [6].In this manuscript we focus on nuclear systems. Generalizing Tan's work, we introduce the nuclear contacts and present an experimental evaluation of the neutron-proton contact in finite nuclei and also in symmetric nuclear matter. To this end we relate the contact to medium energy photonuclear cross-section and utilize available experimental data. In ultracold atomic physics the ratio between the interparticle distance 1/k F , the scattering length a, and r eff can be controlled in such a way as to ensure that the a r eff and k F r eff 1. The nuclear two-body scattering length is about 5.38 fm when the two nucleons are in the 3 S 1 state and about -20 fm when they

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Analysis of209Bi and238U photofission cross section in the quasi-deuteron region of photonuclear absorption

Tavares

Terranova

1992

Z. Physik A - Hadrons and Nuclei

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Abstract. An analysis of the photofission reactions in the quasi-deuteron energy range of photonuclear absorption (~30-140 MeV) has been performed for 2~ and 238U nuclei. Experimental cross section data available in the literature have been compared with calculated values obtained from a model in which the incoming photon is assumed to be absorbed by a neutron-proton pair (Levinger's quasi-deuteron photoabsorption), followed by a mechanism of evaporation-fission competition for the excited residual nuclei. The model has been shown to reproduce the main experimental features of 2~ and ~38U photofission cross section, although unexplained differences still remain in the case of 238U-fission by 30-50 MeV incident photons. 25.85.Jg PACS:

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Evaluation of Total Nuclear Photoabsorption Cross-Sections by the Modified Quasi-Deuteron Model

Cited by 25 publications

References 12 publications

Photoneutron Reaction Data for Nuclear Physics and Astrophysics

Photoneutron Reaction Data for Nuclear Physics and Astrophysics

Nuclear Neutron-Proton Contact and the Photoabsorption Cross Section

Analysis of209Bi and238U photofission cross section in the quasi-deuteron region of photonuclear absorption

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