MEASUREMENT OF RADIATIVE CAPTURE RESONANCE INTEGRALS IN A THERMAL REACTOR SPECTRUM, AND THE THERMAL CROSS SECTION OF Pu-240

1960 ◽  
Vol 38 (1) ◽  
pp. 57-77 ◽  
Author(s):  
W. H. Walker ◽  
C. H. Westcott ◽  
T. K. Alexander
Keyword(s):  
Cross Section ◽  
Neutron Beam ◽  
Cross Sections ◽  
Radiative Capture ◽  
Effective Cross Section ◽  
Mean Value ◽  
Resonance Integral ◽  
Thermal Reactor ◽  
Thermal Cross Section ◽  
Radiative Neutron Capture

An apparatus is described which detects γ-rays emitted by a thin target placed in a well-denned neutron beam. It has been used to determine the Cd ratios of Au and Pu-240, from which the ratio of the resonance integral to the 2200 m/s cross section for radiative neutron capture in Pu-240 has been deduced, using Au as a reference standard. Using this ratio and previously measured values of the resonance integral of Pu-240 and its effective cross section in two positions in the NRX reactor, three separate estimates of the 2200 m/s cross section of Pu-240 have been made. The mean value is 270 ± 17 barns.In an auxiliary experiment to indicate the shape of the epithermal spectrum of the neutron beam, the activation Cd ratios of Mn and In were compared with that of Au. These results, combined with the known 2200 m/s capture cross sections of these nuclides, yield new values of the radiative capture resonance integrals for both Mn and In.

Neutron Activation Resonance Integral of 74Ge and 76Ge and Evaluation of the 74Ge keV Neutron Radiative Capture Cross Section and Resonance Integral

1972 ◽  
Vol 50 (17) ◽  
pp. 1978-1986
Author(s):  
M. D. Ricabarra ◽  
R. Turjanski ◽  
G. H. Ricabarra
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Radiative Capture ◽  
Resonance Integral ◽  
Neutron Resonance ◽  
Capture Cross ◽  
Resonance Parameters ◽  
Radiative Capture Cross Section ◽  
Average Resonance

Values of the reduced activation resonance integral relative to the thermal cross section I′/σ0 of 74Ge and 76Ge were determined relative to gold by measuring cadmium ratios in a reactor spectrum.A lithium-drifted germanium γ-ray spectrometer was used to resolve the activities of the samples.The results for 74Ge are I′/σ0 = 1.514 ± 0.031 and I′ = 0.681 ± 0.123 b with an assumed σ0 = 0.45 ± 0.08 b; for 76GeI′/σ0 = 12.00 ± 0.16 and I′ = 1.992 ± 0.359 with an assumed σ0 = 0.166 ± 0.030 b.The values obtained for I′ are in serious disagreement with the values calculated with neutron resonance parameters and confirm previous results obtained in similar keV average resonance spacing isotopes.Due to this fact a careful evaluation of the keV neutron radiative capture cross section and resonance integral for 74Ge was undertaken.The evaluation and comparison with the experimental value of the resonance integral shows first that for nuclides with an average resonance spacing of keV the unresolved resonance integral has been seriously underestimated in many evaluations, and second that between 10 and 100 keV, resonance integrals calculated with smooth low resolution activation cross sections give a better calculation of neutron captures than that obtained with neutron resonance parameters.

THE CROSS SECTION FOR THE REACTION Cs135(n, γ)Cs136

1958 ◽  
Vol 36 (7) ◽  
pp. 863-870 ◽  
Author(s):  
A. P. Baerg ◽  
F. Brown ◽  
M. Lounsbury
Keyword(s):  
Cross Section ◽  
Reaction Rate ◽  
Effective Cross Section ◽  
Reaction Rates ◽  
Resonance Integral ◽  
A Value ◽  
The Cross ◽  
Thermal Cross Section

The effective cross section for the reaction Cs135 (n, γ) Cs136 with reactor neutrons is 10.4 ± 0.5 barns. The measured reaction rate under cadmium yields a value of 61.7 ± 2.3 barns for the resonance integral of Cs135. The thermal cross section is 8.7 ± 0.5 barns as obtained by combining the reaction rates for uncovered and cadmium-covered samples.

Computer simulation of (n, p) modifications in silicon nitride (Si3N4) nanoparticles

2020 ◽  
Vol 34 (32) ◽  
pp. 2050318
Author(s):  
T. G. Naghiyev
Keyword(s):  
Computer Simulation ◽  
Silicon Nitride ◽  
Stable Isotope ◽  
Cross Section ◽  
Cross Sections ◽  
Effective Cross Section

(n, p) transmutations in the silicon nitride (Si3N4) nanoparticles by the neutrons at different energies have been studied by computer simulation. The transmutations by neutrons in the nanomaterial were separately investigated for silicon and nitrogen atoms in the Si3N4 particles. Since the effective cross-section of the possible probability of transmutation is different in the various types of silicon and nitrogen atoms, the modeling was performed separately for each stable isotope. The spectra of the effective cross-sections of the (n, p) transmutations for silicon and nitrogen atoms have been studied in relation to each other.

scholarly journals Measurement of the 241Am(n,2n)240Am cross section at 17.5 MeV

2019 ◽  
Vol 21 ◽  
pp. 160
Author(s):  
A. Kalamara ◽  
R. Vlastou ◽  
M. Diakaki ◽  
M. Kokkoris ◽  
M. Anastasiou ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Beam ◽  
Cross Sections ◽  
Reaction Cross ◽  
Activation Technique ◽  
Tandem Accelerator ◽  
Hpge Detectors ◽  
Reaction Cross Sections ◽  
Reference Reaction ◽  
High Radioactivity

The 241Am(n,2n)240Am reaction cross section has been measured at neutron beam energy 17.5 MeV, relative to the 27Al(n,α)24Na, 197Au(n,2n)196Au and 93Nb(n,2n)92mNb reference reaction cross sections, using the activation technique. The irradiation was carried out at the Van der Graaff 5.5 MV Tandem accelerator laboratory of NCSR “Demokritos” with monoenergetic neutron beam provided by means of the 3H(d,n)4He reaction, implementing a new Ti-tritiated target. The high purity Am target has been constructed at IRMM, Geel, Belgium and consisted of 40 mg 241Am in the form of AmO2 pressed into pellet with Al2O3 and encapsulated into Al container. Due to this high radioactivity (5 GBq), the Am target was enclosed in a Pb container for safety reasons. After the end of the irradiation, the activity induced by the neutron beam at the target and reference foils, was measured off-line by two 100%, a 50% and a 16% relative efficiency, HPGe detectors.

Effect of Electrostatic Interactions on Effective Cross-Sections for Collision of Small Particles With Neutral Molecules

1993 ◽  
Vol 46 (1) ◽  
pp. 13 ◽  
Author(s):  
LF Phillips
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atmospheric Aerosols ◽  
Electrostatic Interactions ◽  
Interstellar Dust ◽  
Effective Cross Section ◽  
Classical Trajectory ◽  
Polar Molecules ◽  
Interstellar Dust Grains ◽  
Geometrical Cross Section

Quasi-classical trajectory calculations have been used to calculate effective collision cross-sections for polar and non-polar molecules with charged and neutral conducting spheres of radius 0.001-0.1 μm over the temperature range 10-400 K. In general the effective cross-section is much larger than the geometrical cross-section, especially for small, highly charged, particles colliding with highly polar molecules at low temperatures. The results may have a bearing on the growth of atmospheric aerosols and of interstellar dust grains.

The Thermal Neutron Cross Section and the Resonance Integral of 184Os, 190Os, 192Os, 64Zn, 68Zn and 59Co

1968 ◽  
Vol 9 (2-3) ◽  
Author(s):  
J. I. Kim ◽  
F. Adams
Keyword(s):  
Neutron Activation ◽  
Thermal Neutron ◽  
Cross Section ◽  
Cross Sections ◽  
Neutron Cross Section ◽  
Resonance Integral ◽  
Activation Measurement ◽  
Thermal Neutron Cross Section ◽  
Neutron Cross Sections

SummaryBy neutron activation measurement with a cadmium filter, using gold as a standard monitor, the thermal neutron cross sections and the resonance integrals of

THE RATIO OF THE RESONANCE INTEGRAL TO THE THERMAL NEUTRON CROSS SECTION FOR Sm152

1961 ◽  
Vol 39 (8) ◽  
pp. 1184-1192 ◽  
Author(s):  
W. H. Walker ◽  
R. E. Green
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Neutron Cross Section ◽  
Resonance Integral ◽  
Half Maximum ◽  
Thin Foils ◽  
Flight Measurement ◽  
Thermal Neutron Cross Section ◽  
Thermal Cross Section ◽  
Made In

Cadmium ratio measurements have been made in similar lattice positions in ZEEP with thin foils of Sm152 and gold. From a comparison of these cadmium ratios we find[Formula: see text]If gσ0 is assumed to be 212 ± 12 barns, then I′ = 3100 ± 200 barns. On the assumption that only one resonance in Sm152, at 8 ev, contributes appreciably to both the resonance integral and the thermal cross section, it follows that g = 1 and that Γ, the width at half-maximum of the total cross section resonance, is 193 ± 5 milli-ev. Because of the appreciable disagreement between this value and one reported earlier, a new time-of-flight measurement of the resonance parameters has been made, and it is reported in the next paper (Chrien 1961).

First (n, p) measurements with the Indiana University Cyclotron Facility

1987 ◽  
Vol 65 (6) ◽  
pp. 687-690 ◽  
Author(s):  
D. Počanić ◽  
K. Wang ◽  
C. J. Martoff ◽  
S. S. Hanna ◽  
R. C. Byrd ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Beam ◽  
Cross Sections ◽  
Distorted Wave ◽  
Indiana University ◽  
Preliminary Results ◽  
Intermediate Energies ◽  
Set Up ◽  
Wave Calculation ◽  
Good Agreement

A new monochromatic neutron-beam facility has been set up at the Indiana University Cyclotron Facility, primarily for (n, p) reaction measurements at intermediate energies (100–200 MeV). Reported are the experimental layout of the facility and preliminary results of the first measurements: 6Li(n,p)6He cross sections at six angles ranging from Θcm = 0–22°, with En = 118 MeV (laboratory). Good agreement is found between the measured σ(0°) and the cross sections measured for the mirror reaction 6Li(p, n) at 120 and 144 MeV. Results of a distorted wave calculation, while slightly lower, are consistent with the preliminary experimental 0° cross section.

Radiative capture of fast neutrons in 160Gd

1988 ◽  
Vol 66 (4) ◽  
pp. 330-333 ◽  
Author(s):  
R. K. Y. Singh ◽  
M. Afzal Ansari ◽  
R. P. Gautam ◽  
I. A. Rizvi ◽  
S. Kailas
Keyword(s):  
Cross Sections ◽  
Neutron Capture ◽  
Radiative Capture ◽  
Fast Neutrons ◽  
Activation Technique ◽  
Present Measurement ◽  
Radiative Neutron ◽  
Experimental Values ◽  
Radiative Neutron Capture ◽  
Capture Cross Sections

Radiative neutron capture cross sections for 160Gd have been measured at eight different neutron energies: 0.46 ± 0.04, 0.57 ± 0.04, 0.75 ± 0.04, 0.97 ± 0.20, 1.22 ± 0.19, 1.52 ± 0.17, 2.22 ± 0.17, and 3.05 ± 0.18 MeV. The activation technique has been employed in the present measurement. Our experimental values are compared with the theoretical values calculated using the FISPRO II code, using the most recent set of parameters available in the published literatures.

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