Dynamics of nuclear fission at low excitation energy

Dynamics of nuclear fission at low excitation energy
A sample Langevin trajectory (red line) as a function of elongation (horizontal axis) and mass asymmetry parameter (vertical axis) superposed on a potential energy surface.

The mechanisms of nuclear fission, especially the origin of asymmetric mass division in the low-excitation region of U and Pu, are still not clear. There are many conflicting arguments to explain the experimental data, making a proper prediction of unmeasured quantities quite difficult.

In addition, there are many technical problems in generating a realistic dynamical calculation of and its interpretation.

Aritomo, Chiba and Ivaniuk at the Research Laboratory for Nuclear Reactors at Tokyo Institute of Technology have tried to understand the mechanisms of nuclear fission in terms of a dynamical model based on the Langevin equation. Then, the mass asymmetry in the fission of 236U at low excitation energy is clarified by the analysis of the Langevin trajectories.

The potential energy surface and transport coefficients were calculated by the two-center shell model, which includes the shell and pairing effects. This is the only model that can give these quantities starting from a mono-nucleus and moving on toward the separated fragments that appear during fission.

The position of the peaks in the mass distribution of fission fragments from low-energy fission of 236U is determined mainly by the saddle point configuration originating from the shell correction energy. The width of the peaks, on the other hand, results from the shape fluctuations close to the scission point caused by the random force.

The researchers try to understand in a unified way the mechanisms of nuclear fission and correlations of fission-related quantities, to make a step toward a quantitative understanding of fission.


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More information: "Fission dynamics at low excitation energy." Physical Review C 90, 054609-1-8(2014). 10.1103/PhysRevC.90.054609
Citation: Dynamics of nuclear fission at low excitation energy (2015, August 25) retrieved 23 May 2019 from https://phys.org/news/2015-08-dynamics-nuclear-fission-energy.html
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Aug 25, 2015
Consider the potential among the charges that define the nucleus. The neutron is a proton attached to an electron. This configuration without a field is stable. Any field will separate these two particles. remove mass as a primary unit and divide the mass the mass by the sum of the mass of the electron and the proton. At very close range this will be a very strong force and multiple protons may attache to a single electron within the neutron using only the coulomb force. The stability of the nucleus will change as the number pf protons increases. The separation either will eject an electron or a proton or both. The motion creating the ejection will be a very fast action, often within a very tight loop emitting high frequency radiation. Simulating charges as assembled with the known elements shall describe the stability an what type of field or field change that will be able to cause separation, similar to any field over that causes the neutron to split.

Aug 25, 2015
The split is primarily a repulsive force that ejects a particle. An electron moving through the field of negative charges and the balance of charge within the nucleus will define the resultant atom. A proton moving through this field, i.e. a rejected proton due to repulsion will appear as an anti-particle. No particle has been shown to be transparent. I conjecture that these particles are perfectly elastic. Hence, collision will create high frequency radiation due to d^2q/dt^2 as well as d^2q/dr^2. Refining our theory based upon the known physics vs assumptions upon the strong and weak forces, anti-matter, etc. will lead to greater knowledge and better understanding. The above analysis has no accurate model based upon what we have discovered since 1915. Hindsight is very instructive! We should be able to simulate all possibilities for stability and instability. Using the know radiation and particle energy will guide us in defining nuclear motion of fission.

Aug 25, 2015
I suggest once we understand and have the ability to apply these rapidly changing fields to a particular location upon a nucleus will give us control to be able to manipulate the atomic structure. Fusion will require the ability to define the particle position relative to another particle; tricky field control, typically only found within very dense matter where the proximity is defined by magnitude of the number of charges, i.e. the centers of all charges as a primary attractor and the relationship with local charges. Note the strength required for separation and the strength of the net field in a particular direction and self assembly. It may be possible to define a field to define fusion, but think about what we are trying to do.

Aug 25, 2015
Sort of like defining the necessary size of the sun to be able to cause matter to move away from the planet but a proportional to 1/r^2, every where. Hence separation must be to an internal repulsion. What sort of oscillating field is required to move the electron from a group of protons, etc.. or what defines instability, internally? Simple, if the particles have "room" to separate, they will separate, the field is always changing. In order for some to separate they would need within what set of configurations. With superposition, the sate of the position of any two particles are simple overlays with an additive field. So use a 4D space that defines time as distance using c=lambda nu, then the unit of each axis are definable from -infinity to +infinity an the next particle position are defined by the attributes of charge, i.e. Maxwell.

Aug 25, 2015
I prefer using only +1 and -1. Hmmmm, a simple memory space, controlled by ...

Aug 25, 2015
Gee, simply display it! At any speed or position. Just get a lot of pixels or some clever code.

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