High-Resolution Measurements and Calculations of Photon-Production Cross Sections for16O(n,xγ) Reactions Induced by Neutrons with Energies between 4 and 200 MeV

Nelson, R. O.; Chadwick, M.B.; Michaudon, A.; Young, P.G.

doi:10.13182/nse01-a2205

Cited by 24 publications

(35 citation statements)

References 46 publications

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“…On the other hand, in fast neutron-induced reactions on a nucleus with much smaller Z it is the population via α emission that is larger, as was observed in Ref. [3] in reactions on 16 O.…”

Section: Introductionmentioning

confidence: 57%

“…It is based on the Hauser-Feshbach code GNASH [27] with incorporation of a cluster emission model to describe the pre-equilibrium process. This code was used also in the calculations described in the previous LANSCE experiments referenced in this work [1][2][3]. The two nuclear reaction codes used in the present work, GNASH and CoH 3 , are based on the same reaction mechanisms, but the decay of the compound nuclei is calculated differently for the multiple particle emission at high energies.…”

Section: Discussionmentioning

confidence: 99%

“…4.a data from a pre-GEANIE experiment are shown where the α-peak is dominant in the γ-ray-production cross section of the 16 O(n,α/2p2n) 13 C reactions (data taken from figure 15 of Ref. [3]); in Fig. 4.b data from a GEANIE experiment are shown where the α peak is still larger than the (n, 2p2n) peak in the 48 Ti(n,α/2p2n) 45 Ca reactions (data taken from figure 9 of Ref.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, α emission is the most common form of cluster emission in nuclear reactions because of the extremely high binding energy and relatively small mass of the α particle. At higher energies, transmutation reactions that lead to the same isotope can include also lighter particles that sum to the baryon number and charge of the alpha particle, such as 2p + 2n, p + d + n, n+ 3 He, p+ 3 H, and d + d. Calculations indicate that for incident neutron energies well above threshold, the 2p + 2n probability is the largest of these and therefore we will refer to the γ rays we see as being from, for example, "(n, n ′ α)"…”

Section: Introductionmentioning

confidence: 99%

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αand2p2nemission in fast neutron-induced reactions onNi60
Fotiades
¹
,
Devlin
²
,
Haight
³

et al. 2015
Phys. Rev. C
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Background: The cross sections for populating the residual nucleus in the reaction A Z X(n, x)A−4 Z−2 Y exhibit peaks as a function of incident neutron energy corresponding to the (n, n ′ α) reaction and, at higher energy, to the (n, 2p3n) reaction. The relative magnitudes of these peaks vary with the Z of the target nucleus.Purpose: Study fast neutron-induced reactions on 60 Ni. Locate experimentally the nuclear charge region along the line of stability where the cross sections for α emission and for 2p2n emission in fast neutron-induced reactions are comparable as a further test of reaction models.Methods: Data were taken using the GEANIE Ge-detector array. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center's (LANSCE) WNR facility provided neutrons in the energy range from 1 to 250 MeV. The time-of-flight technique was used to determine the incident-neutron energies.Results: Absolute partial cross sections for production of seven discrete Fe γ rays populated in 60 Ni(n, α/2pxnγ) reactions with 2 ≤ x ≤ 5 were measured for neutron energies 1 MeV< E n <250 MeV. Hauser-Feshbach plus pre-equilibrium theoretical calculations are compared to the experimental results.Conclusions: There is good agreement between experimental results and theoretical predictions at lower neutron energies while discrepancies appear at higher neutron energies. The cross section for producing an isotope in fast neutron-induced reactions on stable targets via α emission at the peak of the (n, α) and (n, n ′ α) reactions is comparable to that for 2p2n and 2p3n emission at higher incident energies in the nuclear charge region around Fe. * fotia@lanl.gov

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Section: Introductionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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αand2p2nemission in fast neutron-induced reactions onNi60
Fotiades
¹
,
Devlin
²
,
Haight
³

et al. 2015
Phys. Rev. C
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“…This was performed in previous work [13], [14]. The calculation technique used to obtain the photon-production cross sections with multiple-scattering corrections is described in these references.…”

Section: Methodsmentioning

confidence: 99%

Inelastic partial γ-ray cross sections of [sup 150]Sm+n reactions for E[sub n] = 1–15 MeV

Dashdorj¹,

Kawano²,

Mitchell³

et al. 2011

AIP Conference Proceedings

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The 150 Sm(n,n′γ) reaction was measured from E n = 1 to 15 MeV at the Los Alamos Neutron Science Cemter (LANSCE). The γ rays were detected with the Compton-suppressed Germanium Array for Neutron Induced Excitations (GEANIE). Measured γ-ray excitation functions were converted to partial γ-ray cross sections, Twenty four individual γ-rays up to E x = 1.8 MeV in 150 Sm were measured. Results are compared with enhanced Hauser Feshbach model calculations: the spin distribution in the pre-equilibrium reaction is calculated with the quantum mechanical model of Feshbach, Kerman and Koonin. The particle transmission coefficients were calculated with two different global optical model potential parameter sets. We employed the coupled-channel optical model based on the soft rotor model and with spherical potential.

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A Low O/Si Ratio on the Surface of Mercury: Evidence for Silicon Smelting?

et al. 2017

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Data from the Gamma‐Ray Spectrometer (GRS) that flew on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft indicate that the O/Si weight ratio of Mercury's surface is 1.2 ± 0.1. This value is lower than any other celestial surface that has been measured by GRS and suggests that 12–20% of the surface materials on Mercury are composed of Si‐rich, Si‐Fe alloys. The origin of the metal is best explained by a combination of space weathering and graphite‐induced smelting. The smelting process would have been facilitated by interaction of graphite with boninitic and komatiitic parental liquids. Graphite entrained at depth would have reacted with FeO components dissolved in silicate melt, resulting in the production of up to 0.4–0.9 wt % CO from the reduction of FeO to Fe0—CO production that could have facilitated explosive volcanic processes on Mercury. Once the graphite‐entrained magmas erupted, the tenuous atmosphere on Mercury prevented the buildup of CO over the lavas. The partial pressure of CO would have been sufficiently low to facilitate reaction between graphite and SiO2 components in silicate melts to produce CO and metallic Si. Although exotic, Si‐rich metal as a primary smelting product is hypothesized on Mercury for three primary reasons: (1) low FeO abundances of parental magmas, (2) elevated abundances of graphite in the crust and regolith, and (3) the presence of only a tenuous atmosphere at the surface of the planet within the 3.5–4.1 Ga timespan over which the planet was resurfaced through volcanic processes.

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High-Resolution Measurements and Calculations of Photon-Production Cross Sections for¹⁶O(n,xγ) Reactions Induced by Neutrons with Energies between 4 and 200 MeV

Cited by 24 publications

References 46 publications

αand2p2nemission in fast neutron-induced reactions onNi60
Fotiades
¹
,
Devlin
²
,
Haight
³

et al. 2015
Phys. Rev. C
Self Cite
9
0
10
0
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αand2p2nemission in fast neutron-induced reactions onNi60
Fotiades
¹
,
Devlin
²
,
Haight
³

et al. 2015
Phys. Rev. C
Self Cite
9
0
10
0
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Inelastic partial γ-ray cross sections of [sup 150]Sm+n reactions for E[sub n] = 1–15 MeV

A Low O/Si Ratio on the Surface of Mercury: Evidence for Silicon Smelting?

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High-Resolution Measurements and Calculations of Photon-Production Cross Sections for16O(n,xγ) Reactions Induced by Neutrons with Energies between 4 and 200 MeV

Cited by 24 publications

References 46 publications

αand2p2nemission in fast neutron-induced reactions onNi60Fotiades1, Devlin2, Haight3 et al. 2015Phys. Rev. CSelf Cite90100View full textAdd to dashboardCite

αand2p2nemission in fast neutron-induced reactions onNi60Fotiades1, Devlin2, Haight3 et al. 2015Phys. Rev. CSelf Cite90100View full textAdd to dashboardCite

Inelastic partial γ-ray cross sections of [sup 150]Sm+n reactions for E[sub n] = 1–15 MeV

A Low O/Si Ratio on the Surface of Mercury: Evidence for Silicon Smelting?

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Resources

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High-Resolution Measurements and Calculations of Photon-Production Cross Sections for¹⁶O(n,xγ) Reactions Induced by Neutrons with Energies between 4 and 200 MeV

αand2p2nemission in fast neutron-induced reactions onNi60
Fotiades
¹
,
Devlin
²
,
Haight
³

et al. 2015
Phys. Rev. C
Self Cite
9
0
10
0
View full text Add to dashboard Cite

αand2p2nemission in fast neutron-induced reactions onNi60
Fotiades
¹
,
Devlin
²
,
Haight
³

et al. 2015
Phys. Rev. C
Self Cite
9
0
10
0
View full text Add to dashboard Cite