ACTIVATION OF 93Nb NUCLEI ON THE LINAC LUE-40 OF RDC “ACCELERATOR” AND DETERMINATION OF PHOTONUCLEAR REACTION CROSS-SECTIONS

2019 ◽  
pp. 122-127
Author(s):  
O.M. Vodin ◽  
O.S. Deiev ◽  
S.M. Olejnik
Keyword(s):  
Cross Sections ◽  
Nuclear Reactions ◽  
Total Activity ◽  
Difference Spectrum ◽  
Reaction Cross ◽  
Difference Spectra ◽  
Energy Part ◽  
The Difference ◽  
One And Many ◽  
Reaction Cross Sections

The bremsstrahlung spectra of medium-energy electrons (30…100 МeV) were calculated in GEANT4. Cross-sections for photonuclear reactions were calculated in TALYS1.9. A convolution over the energy of the cross-sections of one- and many-particle reactions with the bremsstrahlung flux density was performed. The numerical values of the yield of 93Nb(γ,xn)93-xNb reactions, the activity of irradiated 93Nb targets, and the average reaction cross-sections were obtained. The differences of the bremsstrahlung spectra from electrons with close initial energies were calculated. The shape of the difference spectra was analyzed. The contributions of the quanta of the low-energy part of the difference spectrum and the quasi-monochromatic peak of the difference spectrum to the total activity of the targets were compared. An approach for correction of the experimental cross-sections of photo-nuclear reactions using the method of "bremsstrahlung spectra difference" was considered.

scholarly journals The feasibility of measuring the nuclear reaction cross sections at energies of several KeV in a target under laser compression

1987 ◽  
Vol 5 (2) ◽  
pp. 399-404 ◽  
Author(s):  
V. I. Kukulin ◽  
V. M. Krasnopol'sky ◽  
V. T. Voronchev
Keyword(s):  
Nuclear Reaction ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Velocity Distribution Function ◽  
Reaction Cross ◽  
Straightforward Method ◽  
Energy Behaviour ◽  
Low Energies ◽  
Ion Velocity Distribution Function ◽  
Reaction Cross Sections

The work proposes a straightforward method for determining the nuclear reaction cross sections at extremely low energies (E ≃ 1–100 keV) on the basis of the measurements of the relative yield of fast particles which are products of the nuclear reactions in a target under laser compression. On the other hand, the proposed method makes it possible to find the averaged form of the ion velocity distribution function if the low-energy behaviour of the respective cross sections is known.

scholarly journals On the Statistical Theory of Nuclear Reactions

1978 ◽  
Vol 31 (2) ◽  
pp. 151 ◽  
Author(s):  
WK Bertram
Keyword(s):  
Statistical Theory ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Reaction Cross ◽  
Open Channels ◽  
S Matrix ◽  
Reaction Cross Sections

The statistical theory of energy-averaged reaction cross sections is examined using the pole expansion of the S-matrix. Exact expressions for the average cross sections in terms of the parameters of the S-matrix are derived for the case when there are two open channels. It is shown that when the number of channels exceeds two, the average cross sections can be evaluated provided the poles of the S-matrix are evenly spaced.

scholarly journals Experimental Investigation of radiative proton-capture reactions relevant to Nucleosynthesis

2019 ◽  
Vol 24 ◽  
pp. 168
Author(s):  
A. Khaliel ◽  
T. J. Mertzimekis ◽  
A. Psaltis ◽  
I. Psyrra ◽  
A. Kanellakopoulos ◽  
...  
Keyword(s):  
Cross Sections ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Theoretical Models ◽  
Reaction Cross ◽  
Tandem Accelerator ◽  
Proton Capture ◽  
Isotopic Abundances ◽  
Vast Network ◽  
Reaction Cross Sections

One of the primary objectives of the field of Nuclear Astrophysics is the study of the elemental and isotopic abundances in our solar system. Although a lot of progress has been made regarding a large number of nuclides, there is still a number of neutron-deficient nuclei, ie the p nuclei, which cannot be created via the s and r processes. These processes are responsible for the production of the bulk of heavy nuclides. The pre-explosive or explosive phases of massive stars are considered potential loci for p nuclides production via various combinations of photodisintegrations and nucleon captures, along with β+ decays and electron captures. For the study of the vast network of nuclear reactions (over 20'000) that are responsible for observed isotopic abundances, the statistical model of Hauser-Feshbach is employed. The model requires the knowledge of nuclear reaction cross sections, quantities that can be measured in the laboratory. In this work, we report on recent experimental attempts to measure such cross sections in radiative proton-capture reactions involving 107,109Ag near the astrophysically relevant energy window. Measurements have been performed at the Tandem Accelerator Laboratory of the N.S.C.R. “Demokritos”. The results are compared to various theoretical models, using the TALYS and EMPIRE codes, in an attempt to provide experimental input to astrophysical models.

scholarly journals A study of 12c +12c nuclear reaction using a new M3Y-type effective interaction

2020 ◽  
Vol 3 (1) ◽  
pp. 133-142
Author(s):  
Ochala Isaiah ◽  
Terver Daniel ◽  
O Fiase Joseph
Keyword(s):  
Cross Sections ◽  
Optical Potential ◽  
Nuclear Reactions ◽  
Effective Interaction ◽  
Heavy Ion ◽  
Reaction Cross ◽  
Double Folding ◽  
Work Done ◽  
Best Fit ◽  
Reaction Cross Sections

This paper is a study of nuclear reactions involving 12C + 12C nuclei carried out with a heavy-ion nucleus-nucleus optical potential derived from a new M3Y-type effective interaction, called B3Y-Fetal, within the framework of optical model at the incident energies of 112, 126.7, 240, 300, 1016 MeV. Folding analyses of the differential cross sections associated with the elastic scattering of the nuclear system, determined at these incident energies with four B3Y-Fetal-based folded potentials constructed from double folding model, have shown the DDB3Y1- and BDB3Y1-Fetal potentials to be the best in excellent agreement with previous work done with the M3Y-Reid. The agreement of the B3Y-Fetal with the famous M3Y-Reid effective interaction, which is also used for folding analysis in this work, is further buttressed and well-established by the findings of this study Herein, the values of the renormalization factor, NR ranging from 1.1117 to 0.8121, obtained with the B3Y-Fetal have been found to be slightly higher, with lower reaction cross sections, aR = 1418 - 1047 millibarns, than NR = 0.9971 - 0.8108 obtained with the M3Y-Reid effective interaction whose accompanying reaction cross sections, being higher, range from 1431 to 1050 millibarns. This depicts the B3Y-Fetal as having a better performance. Additionally, results of folding analyses have shown the best-fit folded potentials, DDB3Y1- and BDB3Y1-Fetal potentials to be in agreement at all incident energies, implying that the cold nuclear matter has an underlying soft equation of state.

Lack of Evidence for Shell Effects in the (n,p) and (n,α) Reaction Cross Sections at 14 MeV Neutron Energy

1970 ◽  
Vol 25 (12) ◽  
pp. 1977
Author(s):  
S.M. Qaim
Keyword(s):  
Experimental Data ◽  
Neutron Energy ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Magic Number ◽  
Reaction Cross ◽  
Conclusive Evidence ◽  
Shell Effects ◽  
Reaction Cross Sections ◽  
Proton Shell

Abstract The systematics of cross sections for (n,p) and (n,a) re-actions induced by 14 - 15 MeV neutrons have been reinvesti-gated. No clear evidence for the existence of any proton shell effects in these two reactions was found. The existence of shell effects in nuclear reactions induced by 14 - 15 MeV neutrons has been postulated by several workers1-4 , but the evidence presented has been rather weak. With the availability of more and better experimental data in recent years, a fresh look at this postulate seemed highly desirable. In case of (n,p) and (n,2n) reactions, the claim for the occurence of shell effects has already been recently repudiated5,6 ; but for (n,α) reactions there seems to exist no evidence against the original claims1,2 that the cross section shows a minimum when the atomic number of the re-sidual nucleus is a magic number. The present article describes briefly a reinvestigation of the systematics of the (n,p) and (n,α) reaction cross sections in the light of the latest experimental data. At 14 MeV neutron energy there appears to be no conclusive evidence for any significant proton shell effects in these two re-actions.

Deformation and orientation effects on reaction cross-sections at intermediate and high energies

2019 ◽  
Vol 28 (03) ◽  
pp. 1950014
Author(s):  
M. Rashdan ◽  
Sh. M. Sewailem
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Local Density ◽  
Nucleon Nucleon ◽  
Reaction Cross ◽  
Glauber Model ◽  
Medium Effects ◽  
High Energies ◽  
The Difference ◽  
Reaction Cross Sections

The effects of deformation and orientation on the nucleus–nucleus and proton–nucleus reaction cross-sections are investigated at intermediate and high energies, in the framework of the Coulomb modified Glauber model. The matter density of the projectile is treated by a deformed Fermi shape with quadrupole and hexadecapole deformations. In-medium effects are included through a local density- and an energy-dependent effective nucleon–nucleon total cross-section. Calculations are performed for the deformed projectiles [Formula: see text] colliding by [Formula: see text] and by protons. It is found that the average of reaction cross-section over all directions of the symmetry axis of the deformed projectile differs by about 2[Formula: see text] compared with that calculated for a spherical projectile with the same rms matter radius as the deformed one. The difference between the cross-sections calculated with and without medium effects is of the order 2[Formula: see text] for both deformed and spherical cases. The integrated reaction cross-sections over all orientation angles provide a consistent explanation of the experimental data. The orientation of the heavy projectile can produce a difference in the calculated cross-section about 35[Formula: see text] for nucleus–nucleus and about 45[Formula: see text] for proton–nucleus. This study is also useful for experiments of polarized beams that have created opportunities to study oriented collisions of deformed nuclei. The method is applied to extract the rms radius of [Formula: see text] and it is found to be about 3.56 and 3.45[Formula: see text]fm when using deformation with and without in-medium effects.

scholarly journals Electron Screening in Nuclear Astrophysics

2020 ◽  
Vol 227 ◽  
pp. 01012
Author(s):  
Matej Lipoglavsek ◽  
Aleksandra Cvetinović
Keyword(s):  
Nuclear Reaction ◽  
Cross Sections ◽  
Inverse Kinematics ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Reaction Cross ◽  
Electron Screening ◽  
Low Energies ◽  
Order Of Magnitude ◽  
Reaction Cross Sections

Electron screening in an important effect that cannot be neglected in nuclear astrophysics, since it influences nuclear reaction cross sections at low energies. We are trying to understand why most measurements in inverse kinematics on solid targets give electron screening potentials more than an order of magnitude above predictions. Below we report our latest results on electron screening in nuclear reactions 1H(14N,γ)15O and 2H(19F,ρ)2°F in both inverse and normal kinematics. The analysis is in progress.

scholarly journals Surrogate nuclear reactions: an indirect method for determining reaction cross sections

2005 ◽  
Vol 31 (10) ◽  
pp. S1687-S1690 ◽  
Author(s):  
J Escher ◽  
L Ahle ◽  
L Bernstein ◽  
J Burke ◽  
J A Church ◽  
...  
Keyword(s):  
Cross Sections ◽  
Indirect Method ◽  
Nuclear Reactions ◽  
Reaction Cross ◽  
Reaction Cross Sections
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