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.

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 Statistical model calculations of 72,73Ge(n,p) and 72,74Ge(n,α) reactions on natural Ge

2020 ◽  
Vol 15 ◽  
pp. 104
Author(s):  
S. Galanopoulos ◽  
R. Vlastou ◽  
P. Demetriou ◽  
M. Kokkoris ◽  
C. T. Papadopoulos ◽  
...  
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Neutron Energy ◽  
Cross Sections ◽  
Reaction Cross ◽  
Model Calculations ◽  
Monoenergetic Neutron ◽  
Theoretical Investigations ◽  
Equilibrium Emission ◽  
Reaction Cross Sections

Systematic experimental and theoretical investigations of the 72,73Ge(n,p)72,73 Ga and 72,74Ge(n,α)69,71Znm reaction cross sections are presented in the energy range from thresh- old to about 17 MeV neutron energy. The above reaction cross sections were measured from 8.8 to 11.4 MeV by using the activation method, relative to the 27Al(n,α)24Na refer- ence reaction. The quasi-monoenergetic neutron beams were produced via the 2H(d,n)3He reaction at the 5 MV VdG Tandem T11/25 accelerator of NCSR “Demokritos”. Statisti- cal model calculations using the code EMPIRE-II (version 2.19) taking into consideration pre-equilibrium emission were performed on the data measured in this work as well as on data reported in literature.

Measurement and covariance analysis of 100Mo (n, 2n) 99Mo and 96Mo (n, p) 96Nb reaction cross sections at the incident neutron energy of 14.54 MeV

2020 ◽  
Vol 325 (3) ◽  
pp. 831-840
Author(s):  
Sangeetha Prasanna Ram ◽  
Jayalekshmi Nair ◽  
Saraswatula Venkata Suryanarayana ◽  
Laxman Singh Danu ◽  
Saroj Bishnoi ◽  
...  
Keyword(s):  
Neutron Energy ◽  
Cross Sections ◽  
Reaction Cross ◽  
Covariance Analysis ◽  
Incident Neutron ◽  
Incident Neutron Energy ◽  
Reaction Cross Sections

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 Theoretical calculation and evaluation of neutron inducedreactions on Pu isotopes

2020 ◽  
Vol 239 ◽  
pp. 03008
Author(s):  
Hairui Guo ◽  
Yinlu Han ◽  
Tao Ye ◽  
Weili Sun ◽  
Wendi Chen
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Nuclear Data ◽  
Reaction Cross ◽  
Driven Systems ◽  
Intranuclear Cascade ◽  
Pu Isotopes ◽  
Design Requirements ◽  
Accelerator Driven Systems ◽  
Reaction Cross Sections

The nuclear data on n+239,240,242,244Pu reactions for the incident energy up to 200 MeV are consistently calculated and evaluated in order to meet the design requirements of Generation-IV reactors and accelerator driven systems. The optical model, the distorted wave Born approximation theory, the Hauser-Feshbach theory, the fission model, the evaporation model, the exciton model and the intranuclear cascade model are used in the calculation, and new experimental data are taken into account. Our data are compared with experimental data and the evaluated data from JENDL-4/HE and TENDL. In addition, the variation tendency of reaction cross sections related to the target mass numbers is obtained, which is very important for the prediction of nuclear data on neutron-actinides reactions because the experimental data are lacking.

Notizen: Empirical Evidence for Shell Effects in (n,p)- and (n,α)-Reaction Cross Sections Induced By 14 Mev Neutrons

1972 ◽  
Vol 27 (6) ◽  
pp. 1015-1016 ◽  
Author(s):  
P. Holmberg
Keyword(s):  
Empirical Evidence ◽  
Cross Section ◽  
Cross Sections ◽  
Shell Structure ◽  
Closed Shell ◽  
Reaction Cross ◽  
Shell Effects ◽  
The Cross ◽  
Closed Shells ◽  
Reaction Cross Sections

Abstract Cross section values for (n,p)-and (n,α)-reactions have been analysed as functions of the proton and neutron numbers of the target nuclei. When these numbers equal or approach those of a closed shell structure, the cross section values tend to increase. Far from closed shells the cross sections are small.

EXCITATION CURVES FOR THE REACTIONS Fe56(n, p)Mn56 AND Co59(n, α)Mn56

1964 ◽  
Vol 42 (6) ◽  
pp. 1030-1036 ◽  
Author(s):  
D. C. Santry ◽  
J. P. Butler
Keyword(s):  
Cross Section ◽  
Neutron Spectrum ◽  
Neutron Energy ◽  
Cross Sections ◽  
Effective Cross Section ◽  
Fission Neutron ◽  
Reaction Cross ◽  
Fission Neutron Spectrum ◽  
Threshold Energies ◽  
Reaction Cross Sections

Excitation curves for the reactions Fe56(n, p)Mn56 and Co59(n, α)Mn56 have been measured by the activation method from near threshold energies to 20.3 Mev. The measurements are relative to the known cross section for the S32(n, p)P32 reaction. Cross sections for both reactions increase smoothly with neutron energy and reach maximum values of 119 ± 4 mb for the Fe56(n, p) reaction at 13.6 Mev and 30.0 ± 0.9 mb for the Co59(n, α) reaction at 14.5 Mev. Above 15 Mev both cross sections decrease with neutron energy. From the excitation curves effective cross-section values for a fission-neutron spectrum have been calculated as 1.04 ± 0.05 mb for the (n, p) reaction and 0.140 ± 0.007 mb for the (n, α) reaction.

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