scholarly journals Study of the photon strength functions and level density in the gamma decay of the n + 234U reaction

2019 ◽  
Vol 211 ◽  
pp. 02002 ◽  
Author(s):  
J. Moreno-Soto ◽  
E Berthoumieux ◽  
E Dupont ◽  
F Gunsing ◽  
O Serot ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Cross Sections ◽  
High Efficiency ◽  
Level Density ◽  
Reaction Cross ◽  
Level Densities ◽  
Strength Functions ◽  
Gamma Decay ◽  
Reaction Cross Sections ◽  
Nuclear Applications

The accurate calculations of neutron-induced reaction cross sections are relevant for many nuclear applications. The photon strength functions and nuclear level densities are essential inputs for such calculations. These quantities for 235U are studied using the measurement of the gamma de-excitation cascades in radiative capture on 234U with the Total Absorption Calorimeter at n_TOF at CERN. This segmented 4π gamma calorimeter is designed to detect gamma rays emitted from the nucleus with high efficiency. This experiment provides information on gamma multiplicity and gamma spectra that can be compared with numerical simulations. The code DICEBOXC is used to simulate the gamma cascades while GEANT4 is used for the simulation of the interaction of these gammas with the TAC materials. Available models and their parameters are being tested using the present data. Some preliminary results of this ongoing study are presented and discussed.

scholarly journals Microscopie Calculations of Nuclear Level Densities and Astrophysical Applications

2019 ◽  
Vol 11 ◽  
Author(s):  
P. Demetriou ◽  
S. Goriely
Keyword(s):  
Cross Sections ◽  
Level Density ◽  
Reaction Cross ◽  
Neutron Resonance ◽  
Thermodynamic Quantities ◽  
Microscopic Approach ◽  
Level Densities ◽  
Hartree Fock ◽  
The Impact ◽  
Reaction Cross Sections

A new level density formula based on a microscopic calculation of the thermodynamic quantities using the deformed Hartree-Fock-BCS method is proposed. In the microscopic approach shell, pairing and deformation effects on the thermodynamic quantities are treated consistently. The final level density formula is shown to be in close agreement with experimental neutron resonance spacings and low energy states. The impact of the newly-determined level densities on nuclear reaction cross sections and rates of relevance in astrophysics applications is presented.

scholarly journals Calculations of (γ,n) Reaction Cross Sections using Different Level Density Models for Some Lanthanide Nuclei

2015 ◽  
Vol 128 (2B) ◽  
pp. B-228-B-231 ◽  
Author(s):  
U. Akçaalan ◽  
R. Ünal ◽  
İ.H. Sarpün ◽  
H.A. Yalim ◽  
B. Oruncak
Keyword(s):  
Cross Sections ◽  
Level Density ◽  
Reaction Cross ◽  
Level Density Models ◽  
Reaction Cross Sections

scholarly journals CROSS-SECTIONS IN PHOTONUCLEAR REACTIONS WITH MULTIPLE NEUTRON EMISSION

2019 ◽  
pp. 144-148
Author(s):  
O.A. Bezshyyko ◽  
O.M. Vodin ◽  
L.O. Golinka-Bezshyyko ◽  
A.V. Kotenko ◽  
V.A. Kushnir ◽  
...  
Keyword(s):  
Energy Dependence ◽  
Cross Sections ◽  
Neutron Emission ◽  
Reaction Cross ◽  
Photonuclear Reactions ◽  
Level Densities ◽  
Relative Contribution ◽  
Dipole Resonance ◽  
Talys 1.8 Code ◽  
Reaction Cross Sections

The energy dependence of the reaction cross-sections A(γ,xn)(A-xn) was studied in the energy range 19...70 MeV, i.e. beyond Great Dipole Resonance (GDR) region. Experimental data were taken from international database EXFOR for range of nuclear mases (55 < A < 209). Theoretical values of cross sections were obtained using TALYS-1.8 code. Several models of level densities with both enabled and disabled pre-equilibrium mechanism were considered in our simulations. Obtained results let us to make conclusions about different mechanisms of photonuclear reactions on certain nuclei, energy dependence of their relative contribution.

scholarly journals Statistical Hauser-Feshbach Model Description of (n,α) Reaction Cross Sections for the Weak s-Process

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 25
Author(s):  
Sema Küçüksucu ◽  
Mustafa Yiğit ◽  
Nils Paar
Keyword(s):  
Cross Sections ◽  
Density Functional ◽  
Experimental Studies ◽  
Reaction Cross ◽  
Model Description ◽  
Energy Density Functional ◽  
Model Calculations ◽  
Level Densities ◽  
Environment Model ◽  
Reaction Cross Sections

The (n,α) reaction contributes in many processes of energy generation and nucleosynthesis in stellar environment. Since experimental data are available for a limited number of nuclei and in restricted energy ranges, at present only theoretical studies can provide predictions for all astrophysically relevant (n,α) reaction cross sections. The purpose of this work is to study (n,α) reaction cross sections for a set of nuclei contributing in the weak s-process nucleosynthesis. Theory framework is based on the statistical Hauser-Feshbach model implemented in TALYS code with nuclear masses and level densities based on Skyrme energy density functional. In addition to the analysis of the properties of calculated (n,α) cross sections, the Maxwellian averaged cross sections are described and analyzed for the range of temperatures in stellar environment. Model calculations determined astrophysically relevant energy windows in which (n,α) reactions occur in stars. In order to reduce the uncertainties in modeling (n,α) reaction cross sections for the s-process, novel experimental studies are called for. Presented results on the effective energy windows for (n,α) reaction in weak s-process provide a guidance for the priority energy ranges in the future experimental studies.

Proton Strength Functions from (p, n) Reaction Cross Sections

1958 ◽  
Vol 109 (6) ◽  
pp. 2098-2104 ◽  
Author(s):  
J. P. Schiffer ◽  
L. L. Lee
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Strength Functions ◽  
Reaction Cross Sections

Proton Reaction Cross Sections and Strength Functions

1966 ◽  
Vol 145 (3) ◽  
pp. 957-962 ◽  
Author(s):  
A. J. Elwyn ◽  
A. Marinov ◽  
J. P. Schiffer
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Strength Functions ◽  
Reaction Cross Sections

scholarly journals Cross-section measurements of the 94Mo(γ,n) and 90Zr(γ,n) reactions using real photons at the HIγS facility

2018 ◽  
Vol 178 ◽  
pp. 03007
Author(s):  
Adriana Banu ◽  
Jack Silano ◽  
Hugon Karwowski ◽  
Evan Meekins ◽  
Megha Bhike ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
National Laboratory ◽  
Mass Region ◽  
Reaction Cross ◽  
Photon Beams ◽  
Los Alamos National Laboratory ◽  
Section Measurement ◽  
Strength Functions ◽  
Reaction Cross Sections

The photodisintegration reaction cross-sections for 94Mo(γ,n) and 90Zr(γ,n) have been experimentally investigated with quasi-monochromatic photon beams at the High Intensity γ-Ray Source (HIγS) facility, Triangle University Nuclear Laboratory (TUNL). The measurements were focused primarily on studying the energy dependence of the photoneutron cross sections, which is the most direct way of testing statistical models, and were performed close to the respective neutron thresholds and above up to ~ 20 MeV. Neutrons from the (γ,n) reactions were detected using a 4π assembly of 3He proportional counters developed at Los Alamos National Laboratory and presently available at TUNL. While the 94Mo(γ,n) cross section measurement aims to contribute to a broader investigation for understanding the γ-process (the mechanism responsible for the nucleosynthesis of the so-called p-nuclei), the information from the 90Zr(γ,n) data is relevant to constrain QRPA calculations of γ-ray strength functions in this mass region. In this contribution, we will present our preliminary results of the total (γ,n) excitation functions for the two photoneutron reactions on 94Mo and 90Zr.

scholarly journals A 4π γ-summing method for cross-section measurements of capture reactions

2020 ◽  
Vol 15 ◽  
pp. 111
Author(s):  
A. Spyrou ◽  
H.-W. Becker ◽  
A. Lagoyannis ◽  
S. Harissopulos ◽  
C. Rolfs
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Large Volume ◽  
Coulomb Barrier ◽  
Reaction Cross Section ◽  
High Efficiency ◽  
Reaction Cross ◽  
Capture Reaction ◽  
Stellar Nucleosynthesis ◽  
Reaction Cross Sections

Capture reaction cross sections at energies far below the Coulomb barrier are of major importance for the understanding of stellar nucleosynthesis. Since the cross sections of the majority of these reactions are very small, the use of high efficiency detectors is essential. In this work, a new method for capture reaction cross section measurements based on a large volume 4π NaI detector is presented.

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