FISSION FRAGMENT IRRADIATIONS OF HYDROCARBONS: I. YIELD AND ISOTOPIC COMPOSITION OF HYDROGEN FROM MIXTURES OF CYCLOHEXANE AND BENZENE WITH THEIR DEUTERATED ANALOGUES

1964 ◽  
Vol 42 (6) ◽  
pp. 1418-1425 ◽  
Author(s):  
A. W. Boyd ◽  
H. W. J. Connor
Keyword(s):  
Isotopic Composition ◽  
Fission Fragment ◽  
Hydrogen Yield ◽  
Transient Species ◽  
Hydrogen Formation ◽  
Fission Fragments ◽  
Gamma Radiolysis

Cyclohexane and benzene and mixtures of each of these with cyclohexane-d12 and benzene-d6 have been irradiated with fission fragments using thin sources of [Formula: see text]. The hydrogen yield G(H2) for cyclohexane is 7.73, and is only slightly reduced by the addition of benzene. G(H2) for benzene is 2.14. The isotopic composition of the hydrogen from the four mixtures indicates that most is formed in bimolecular processes.To correlate these results with those obtained in gamma radiolysis, a mechanism is proposed based on hydrogen formation by reactions between transient species in both cyclohexane and benzene.

scholarly journals On the isotopic composition of fission fragments

2021 ◽  
Vol 812 ◽  
pp. 136017
Author(s):  
C. Schmitt ◽  
P. Möller
Keyword(s):  
Isotopic Composition ◽  
Fission Fragments

Fission fragment damage to crystal lattices: heat-sensitive crystals

1963 ◽  
Vol 274 (1357) ◽  
pp. 239-252 ◽  
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Fission Fragment ◽  
Crystal Lattices ◽  
Fission Fragments ◽  
Intrinsic Semiconductor ◽  
Transmission Electron ◽  
Ionization Processes ◽  
Cylindrical Volume ◽  
Uranium Fission

An earlier paper (Bowden & Chadderton 1962) has described the damage produced by uranium fission fragments in the lattices of stable crystals. There is evidence that the lattice disarray is caused by both displacement and ionization processes. This paper deals with damage in thermally unstable crystals. Thin single crystals of silver cyanamide, the thiocyanates of silver and mercury (II), the picrates of ammonium, potassium and thallium, ammonium iodate, and ammonium borofluoride have been irradiated and directly examined by transmission electron microscopy. A considerable variation was found in the type and amount of damage. According to the irradiated material, each fragment produces a track of up to 140Å in width, which can represent either missing material (white track) or an alteration to the crystal structure (black track), and which can be either continuous or discontinuous. With some materials the damage does not take the form of a visible track. The observed amount of damage is found to be consistent with that calculated on the basis of a model of damage by heat alone, involving either decomposition or evaporation. An important parameter is the radius of the cylindrical volume within which the energy lost by the fission fragment appears as heat. This radius is determined primarily by the range of the electrons which are released by the passage of the fragment, and which transfer its energy to the crystal lattice. It is likely that only in an intrinsic semiconductor is the range of these electrons low enough for the production of visible tracks in single crystals. The possibility of further damage or explosion, subsequent to irradiation, is briefly considered.

scholarly journals Microscopic Calculation of Fission Fragment Distributions in Actinides

2020 ◽  
Vol 242 ◽  
pp. 03001
Author(s):  
N. Schunck
Keyword(s):  
Fission Fragment ◽  
Initial Conditions ◽  
Quantum Mechanical ◽  
Incident Neutron ◽  
Incident Neutron Energy ◽  
Fission Fragments ◽  
Microscopic Calculation ◽  
Precise Knowledge ◽  
Quantum Mechanical Description ◽  
Induced Fission

The simulation of independent and cumulative yields requires precise knowledge of the initial conditions of the fission fragments immediately after scission. In this paper, we use a quantum-mechanical description of fission dynamics to extract the initial mass distribution of fission fragments for the neutron-induced fission of the two major actinides 239 Pu and 235 U, both for thermal fission and as a function of the incident neutron energy.

MEASUREMENT OF FISSION FRAGMENT ANISOTROPIES FOR PROTON-INDUCED FISSION OF TWO PRE-ACTINIDE NUCLEI AT SEVERAL ENERGIES

2007 ◽  
Vol 22 (05) ◽  
pp. 1027-1037 ◽  
Author(s):  
S. SOHEYLI ◽  
H. NOSHAD ◽  
M. LAMEHI-RACHTI
Keyword(s):  
Angular Distribution ◽  
Statistical Model ◽  
Cross Sections ◽  
Fission Fragment ◽  
Anomalous Behavior ◽  
Surface Barrier ◽  
Mass Asymmetry ◽  
Fission Fragments ◽  
Induced Fission ◽  
Barrier Detectors

The angular distribution of fission fragments has been measured for proton-induced fission of 197 Au and 209 Bi nuclei at several energies between 25 and 30 MeV using surface-barrier detectors. The measured anisotropies are found to be in agreement with the predictions of the standard saddle-point statistical model. The measured anisotropies for neither of the nuclei show any anomalous behavior as a function of both energy and entrance channel mass asymmetry. The fission cross sections of 197 Au and 209 Bi nuclei were also measured and compared with that of the previous works.

scholarly journals Implementing and testing theoretical fission fragment yields in a Hauser-Feshbach statistical decay framework

2018 ◽  
Vol 169 ◽  
pp. 00006 ◽  
Author(s):  
Patrick Jaffke ◽  
Peter Möller ◽  
Ionel Stetcu ◽  
Patrick Talou ◽  
Christelle Schmitt
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Fission Fragment ◽  
Energy Surface ◽  
Prompt Neutron ◽  
Fission Fragments ◽  
Statistical Decay ◽  
Γ Ray ◽  
The Impact

We implement fission fragment yields, calculated using Brownian shape-motion on a macroscopic-microscopic potential energy surface in six dimensions, into the Hauser-Feshbach statistical decay code CGMF. This combination allows us to test the impact of utilizing theoretically-calculated fission fragment yields on the subsequent prompt neutron and γ-ray emission. We draw connections between the fragment yields and the total kinetic energy TKE of the fission fragments and demonstrate that the use of calculated yields can introduce a difference in the 〈TKE〉 and, thus, the prompt neutron multiplicity v, as compared with experimental fragment yields. We deduce the uncertainty on the 〈TKE〉 and v from this procedure and identify possible applications.

scholarly journals Anisotropy in fission fragment and prompt neutron angular distributions

2021 ◽  
Vol 256 ◽  
pp. 00009
Author(s):  
A.E. Lovell ◽  
P. Talou ◽  
I. Stetcu ◽  
K.J. Kelly
Keyword(s):  
Angular Distribution ◽  
Fission Fragment ◽  
National Laboratory ◽  
Angular Distributions ◽  
Event Generator ◽  
Alamos National Laboratory ◽  
New Developments ◽  
Fission Event ◽  
Los Alamos National Laboratory ◽  
Fission Fragments

Several physics mechanisms can lead to the deviation from an isotropic angular distribution for both fission fragments and the neutrons that are emitted during the fission event. Two of these effects have recently been implemented into CGMF, the Monte Carlo fission event generator developed at Los Alamos National Laboratory: angular distribution sampling for fission fragments and pre-equilibrium neutrons (those emitted before the compound nucleus forms). Using these new developments, we show that the anisotropy of the neutrons reflects the anisotropy of the fission fragments, in particular as the outgoing energy of neutrons increases. Correlations between the fission fragment and neutron anisotropies could be used to extract the fission fragment anisotropy from the neutron angular distributions.

Radiolysis of methylcyclohexane. III. Pure vapor phase and effects of additives

1967 ◽  
Vol 45 (14) ◽  
pp. 1649-1659 ◽  
Author(s):  
W. J. Holtslander ◽  
G. R. Freeman
Keyword(s):  
Vapor Phase ◽  
Secondary Reaction ◽  
Hydrogen Yield ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Hydrogen Formation ◽  
Positive Ions ◽  
Total Ionization ◽  
Different Types ◽  
Increasing Temperature

The radiolysis of methylcyclohexene (MCH) vapor was carried out under a variety of conditions. The G-values of the main products at 110°, extrapolated to zero dose, are hydrogen (5.2), methylcyclohexene isomers (2.0), ethylene (1.5), methane (1.3), propylene (0.8), and total dimer (0.3). Other products were also measured.The hydrogen yield was reduced to G = 3.1 by each of the additives, N2O, SF6, and CCL4, and to G = 1.6 by C2H4. Both DI and ND3 increased the total hydrogen yield above the value in pure MCH. In pure MCH approximately 50% of the ions (G(total ionization) = 4.4) resulted in hydrogen formation, whereas in the presence of DI or ND3, 75% of the ions are hydrogen precursors. Thus three different types of positive ions are distinguished in the system: G(M1+) = 2.1, G(M2+) = 1.3, and G(N+) = 1.0.The average ion lifetime with respect to neutralization was 10−3 s. The ion DI−was therefore stable with respect to decomposition to D + I− for a period greater than 10–3 s under the conditions of the experiments (~380 Torr MCH, 110°).The yield of methylcyclohexene isomers increased with increasing temperature and increased upon addition of ND3 or C2H4 to the radiolysis system. The dimer yield was also enhanced by the addition of ND3. This effect was explained by the occurrence of an ionic secondary reaction that destroys methylcyclohexene and (or) methylcyclohexyl radicals in pure MCH.Approximately 85% of the methane is produced by methyl radicals abstracting hydrogen atoms from MCH.

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