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Photodisintegration is endothermic (energy absorbing) for atomic nuclei lighter than iron and sometimes exothermic (energy releasing) for atomic nuclei heavier than iron. Photodisintegration is responsible for the nucleosynthesis of at least some heavy, proton-rich elements via the p-process in supernovae of type Ib, Ic, or II. This causes the ...
According to Fleming [7] there is direct evidence that remarkably long-lived wavelike electronic quantum coherence plays an important part in energy transfer processes during photosynthesis, which can explain the extreme efficiency of the energy transfer because it enables the system to sample all the potential energy pathways, with low loss ...
This is the region of nucleosynthesis within which the isotopes with the highest binding energy per nucleon are created. Heavier elements can be assembled within stars by a neutron capture process known as the s-process or in explosive environments, such as supernovae and neutron star mergers , by a number of other processes.
The latter figure means that a nuclear fission explosion or criticality accident emits about 3.5% of its energy as gamma rays, less than 2.5% of its energy as fast neutrons (total of both types of radiation ~6%), and the rest as kinetic energy of fission fragments (this appears almost immediately when the fragments impact surrounding matter, as ...
Main nuclear reaction chains for Big Bang nucleosynthesis. Big Bang nucleosynthesis began roughly about 20 seconds after the big bang, when the universe had cooled sufficiently to allow deuterium nuclei to survive disruption by high-energy photons. (Note that the neutron–proton freeze-out time was earlier).
Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions.. In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes called helium burning, carbon burning, oxygen burning, and silicon burning, in which the byproducts of one nuclear fuel become, after ...
Nuclear fission is the reverse process to fusion. For nuclei heavier than nickel-62 the binding energy per nucleon decreases with the mass number. It is therefore possible for energy to be released if a heavy nucleus breaks apart into two lighter ones. The process of alpha decay is in essence a special type of spontaneous nuclear fission. It is ...
The largest source of fission products is from nuclear reactors. In current nuclear power reactors, about 3% of the uranium in the fuel is converted into fission products as a by-product of energy generation. Most of these fission products remain in the fuel unless there is fuel element failure or a nuclear accident, or the fuel is reprocessed.