GAMMA–NEUTRON REACTIONS IN O16 AND N14

1952 ◽  
Vol 30 (3) ◽  
pp. 159-164 ◽  
Author(s):  
R. N. H. Haslam ◽  
H. E. Johns ◽  
R. J. Horsley
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Yield ◽  
Gamma Ray ◽  
Yield Curve ◽  
Specific Activity ◽  
Initial Portion ◽  
Activity Curve ◽  
Section Curve ◽  
Peak Cross Section

The cross sections for the reactions O16(γ, n)O15 and N14(γ, n)N13 have been determined by measurement of the induced positron activities. The oxygen cross-section curve has a slowly increasing initial portion after which it rises rapidly to a maximum peak cross section of 11.4 millibarns at 24.0 Mev. The nitrogen cross-section curve has an initial peak at about 13 Mev. Above 17 Mev., this curve increases sharply to a maximum value of 2.84 millibarns at 24 Mev. In order to explain the shape of the nitrogen curve, a relative total neutron yield curve has been determined from 12 to 20 Mev. by detecting the emitted neutrons with a rhodium foil. This neutron yield curve has the same shape as the nitrogen saturated specific activity curve. The anomalous shapes of the nitrogen and oxygen cross-section curves are explained in terms of the variation of gamma-ray absorption with energy.

Bremsstrahlung linear polarization

1989 ◽  
Vol 67 (6) ◽  
pp. 545-561
Author(s):  
W. Del Bianco ◽  
M. Carignan
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Linear Polarization ◽  
Differential Cross ◽  
Born Approximation ◽  
Gamma Ray ◽  
High Energy ◽  
Scattered Electron ◽  
Triple Differential Cross Section

The dependence of the bremsstrahlung perpendicular and parallel triple differential cross sections and the linear polarization on the angles and energies of the incident and scattered electron and of the emitted gamma-ray has been studied in the high-energy small-angle hypothesis. The expression used for the bremsstrahlung triple differential cross section is valid in the Born approximation and for an unscreened Coulomb potential of the nucleus.

scholarly journals 14.8 MeV Neutron Activation Cross Section Measurements for Ge Isotopes

2009 ◽  
Vol 1 (2) ◽  
pp. 173-181 ◽  
Author(s):  
M. M. Haque ◽  
M. T. Islam ◽  
M. A. Hafiz ◽  
R. U. Miah ◽  
M. S. Uddin
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Activation Cross Section ◽  
Section Data ◽  
Gamma Ray Spectroscopy ◽  
24Na Reaction ◽  
The Cross ◽  
Good Agreement

The cross sections of Ge isotopes were measured with the activation method at 14.8 MeV neutron energy. The quasi-monoenergetic neutron beams were produced via the 3H(d,n)4He reaction at the 150 kV J-25 neutron generator of INST, AERE. The characteristics γ-lines of the product nuclei were measured with a closed end coaxial 17.5 cm2 high purity germanium (HPGe) detector gamma ray spectroscopy. The cross sections were determined with reference to the known 27Al(n,α)24Na reaction. Cross section data are presented for 72Ge(n,p)72Ga, 74Ge(n,α)71mZn and 76Ge(n,2n)75m+gGe reactions. The cross section values obtained for the above reactions were 24.78±1.75 mb, 1.69±0.11 mb and 860±50 mb, respectively. The results obtained were compared with the values reported in literature as well as theoretical calculation performed by the statistical code SINCROS-II. The experimental data were found fairly in good agreement with the calculated and literature data.  Keywords: Activation cross section; Neutron induced reaction; Gamma-ray spectroscopy; 14.8 MeV. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i2.1532  

PHOTONEUTRON CROSS SECTIONS IN SILICON AND CALCIUM

1953 ◽  
Vol 31 (1) ◽  
pp. 70-77 ◽  
Author(s):  
R. G. Summers-Gill ◽  
R. N. H. Haslam ◽  
L. Katz
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Neutron Yield ◽  
Threshold Energy ◽  
Threshold Effect ◽  
Monitoring Method ◽  
Dose Monitoring ◽  
Γ Rays ◽  
Integrated Cross Section ◽  
Peak Value

Using the dropping apparatus and dose monitoring method previously reported, the cross sections for the reactions Si28(γ, n)Si27 and Ca40(γ, n)Ca39 have been measured by detecting positron activities in the residual nuclei. The Si28(γ, n)Si27 cross section has a peak value of 21 mbarns at 20.9 Mev. and an integrated cross section to 24 Mev. of 0.070 Mev-barns. The threshold energy is 16.9 ± 0.1 Mev. The Ca40(γ, n)Ca39 cross section has a peak value of 15 mbarns at 19.3 Mev. and an integrated cross section to 24 Mev. of 0.065 Mev-barns. The threshold is 15.8 ± 0.1 Mev.A comparison of our results with the neutron yield measurement of Price and Kerst at 18 and 22 Mev. gives good agreement. A further comparison with the neutron yield work of Baldwin and Elder is made.The sharp discontinuity in (γ, n) yields using lithium γ rays observed by Wäffler and Hirzel is explained as a threshold effect. Integrated cross sections increase more or less smoothly with Z.In addition, improved values for the half-lives of the residual nuclei Si27 and Ca39 have been measured. These are 4.45 ± 0.05 and 1.00 ± 0.03 sec. respectively.

scholarly journals Cross Section Measurements in the 54Cr(p, ?)55Mn Reaction

1979 ◽  
Vol 32 (4) ◽  
pp. 335 ◽  
Author(s):  
R. J. Wilkinson ◽  
A S. R. Kennett ◽  
A Z. E. Switkowski ◽  
D. G. SargoodA and F. M. MannC
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross Section ◽  
Proton Energy ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Model Calculations ◽  
Global Parameter ◽  
Dramatic Effect ◽  
Bombarding Energy

Cross sections for production of individual y rays in the 54Cr(p, y)55Mn reaction have been measured over the proton energy range 1�0-3�8 MeV. Gamma-ray yields are observed to fall by factors of between 5 and 10 at the crossing of the neutron threshold for a proton bombarding energy of 2�2 MeV. Statistical model calculations with global parameter sets successfully account for the dramatic effect of neutron competition on the (p, y) cross section, and at the same time correctly predict the 54Cr(p,n)54Mn reaction cross section.

PHOTONEUTRON REACTIONS IN G12 AND O16

1961 ◽  
Vol 39 (5) ◽  
pp. 643-656 ◽  
Author(s):  
J. P. Roalsvig ◽  
Ishwar C. Gupta ◽  
R. N. H. Haslam
Keyword(s):  
Cross Section ◽  
Yield Curve ◽  
Bremsstrahlung Energy ◽  
The Cross ◽  
Section Curve ◽  
Maximum Bremsstrahlung Energy ◽  
The University

Absolute yields of the reactions C12(γ,n)C11 and O16(γ,n)O15 have been determined at 22-Mev maximum bremsstrahlung energy using the University of Saskatchewan 24-Mev betatron. For the reaction C12(γ,n)C11 a yield curve from threshold to 24 Mev has been obtained and the cross-section curve for the reaction computed. A thorough comparison with other results has been made.

Measurement of Intermediate Energy Gamma-Ray Cross Sections

1971 ◽  
Vol 49 (9) ◽  
pp. 1167-1178 ◽  
Author(s):  
L. C. Henry ◽  
T. J. Kennett
Keyword(s):  
Pair Production ◽  
Production Process ◽  
Cross Section ◽  
Cross Sections ◽  
Energy Region ◽  
Gamma Ray ◽  
Intermediate Energy ◽  
Energy Gamma ◽  
Pair Production Process ◽  
Better Than

Gamma-ray cross sections for 30 well-distributed energies from 121 keV to 10.827 MeV in 9 target elements ranging from carbon to uranium have been measured with an accuracy of better than 1%. Deviations from recently quoted theoretical cross sections were observed in the energy region from 6–11 MeV, particularly for high-Z target materials. The approximately Z2 dependent deviations are certainly associated with the elastic pair-production process, the present opinion being that they arise from an overestimation of the effects of atomic–electron screening on the pair cross section in the intermediate energy region.

Effect of the pigmy resonance on the calculations of the neutron capture cross section

1969 ◽  
Vol 47 (24) ◽  
pp. 2849-2857 ◽  
Author(s):  
J. S. Brzosko ◽  
E. Gierlik ◽  
A. Soltan Jr. ◽  
Z. Wilhelmi
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Neutron Capture ◽  
Capture Cross Section ◽  
Gamma Ray ◽  
Giant Resonance ◽  
Model Calculations ◽  
Experimental Values ◽  
Made In

A comparison of the experimental cross sections of the (n, γ) reaction for several nuclei (103Rh, 127I, 181Ta, 197Au) with the compound nucleus model calculations has been made. In the formula used for the probability of gamma-ray emission from the compound nucleus, the presence of the well-known giant resonance was accounted for, as well as the presence of the "pigmy resonance" appearing at the energy Eγ ≈ 6 MeV. The agreement with the experimental values is better in this case than when the "pigmy resonance" is neglected. The same conclusions can be obtained from the calculations of the shape of the spectrum of neutron capture and from the Γγ/D ratio.

EXCITATION CURVES FOR THE (n, 2n), (n, p), AND (n, nα) REACTIONS OF 65Cu

1966 ◽  
Vol 44 (5) ◽  
pp. 1183-1193 ◽  
Author(s):  
D. C. Santry ◽  
J. P. Butler
Keyword(s):  
Cross Section ◽  
Neutron Spectrum ◽  
Cross Sections ◽  
Effective Cross Section ◽  
Fission Neutron ◽  
A Value ◽  
Fission Neutron Spectrum ◽  
Maximum Value ◽  
Section Curve ◽  
Threshold Energies

Cross sections for the reactions 65Cu (n, 2n)64Cu, 65Cu(n, p)65Ni, and 65Cu(n, nα)61Co have been measured by the activation method from threshold energies up to 20.2 MeV. The measurements are relative to the known cross section for the reaction 32S(n, p)32P. The (n, 2n) cross-section curve increases smoothly with energy and reaches a maximum value of 1 085 ± 60 mb at about 18 MeV. The (n, p) reaction reaches a maximum value of 21.7 ± 1.2 mb at 13.9 MeV. The (n, nα) reaction has a minimum detectable value of 0.3 ± 0.1 mb near 14 MeV and increases to a value of 18.9 ± 0.9 mb at 19.8 MeV. Effective cross-section values for a fission-neutron spectrum calculated from these results are 0.251 ± 0.018 mb for the (n, 2n) reaction and 0.523 ± 0.030 mb for the (n, p) reaction.

scholarly journals Experimental consolidation and absolute measurement of the $$^\text {nat}$$C(p,x)$$^{11}$$C nuclear activation cross section at 100 MeV for particle therapy physics

2021 ◽  
Vol 57 (8) ◽  
Author(s):  
Claus Maximilian Bäcker ◽  
Felix Horst ◽  
Wihan Adi ◽  
Christian Bäumer ◽  
Marcel Gerhardt ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Proton Therapy ◽  
Gamma Ray ◽  
Absolute Measurement ◽  
Nuclear Data ◽  
Particle Therapy ◽  
Absolute Cross Section ◽  
Activation Cross Section ◽  
Gamma Ray Spectrometer

AbstractThe $$^\text {nat}$$ nat C(p,x)$$^{11}$$ 11 C reaction has been discussed in detail in the past [EXFOR database, Otuka et al. (Nuclear Data Sheets 120:272–276, 2014)]. However, measured activation cross sections by independent experiments are up to 15% apart. The aim of this study is to investigate underlying reasons for these observed discrepancies between different experiments and to determine a new consensus reference cross section at 100 MeV. Therefore, the experimental methods described in the two recent publications [Horst et al. (Phys Med Biol https://doi.org/10.1088/1361-6560/ab4511, 2019) and Bäcker et al. (Nuclear Instrum Methods Phys Res B 454:50–55, 2019)] are compared in detail and all experimental parameters are investigated for their impact on the results. For this purpose, a series of new experiments is performed. With the results of the experiments a new reference cross section of (68±3) mb is derived at (97±3) MeV proton energy. This value combined with the reliably measured excitation function could provide accurate cross section values for the energy region of proton therapy. Because of the well-known gamma-ray spectrometer used and the well-defined beam characteristics of the treatment machine at the proton therapy center, the experimental uncertainties on the absolute cross section could be reduced to 3%. Additionally, this setup is compared to the in-beam measurement setup from the second study presented in the literature (Horst et al. 2019). Another independent validation of the measurements is performed with a PET scanner.

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