Neutron diffusion and nucleosynthesis

In summary, this article presents a new code for Big Bang Nucleosynthesis in an inhomogeneous model of the universe. It calculates neutron diffusion and nucleosynthesis simultaneously and shows how the timing of neutron diffusion affects the final abundances of He4, deuterium and Li7. These results are compared with observational data and suggest that the inhomogeneous model has larger ranges for the baryon to photon ratio and depletion factor compared to the standard model. The question of why the universe is baryon inhomogeneous after inflation is raised but remains unanswered.
  • #1
wolram
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http://arxiv.org/abs/astro-ph/0506364

Title: Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model
Authors: Juan F. Lara
Comments: accepted for publication in Physical Review D

This article presents an original code for Big Bang Nucleosynthesis in a baryon inhomogeneous model of the universe. In this code neutron diffusion between high and low baryon density regions is calculated simultaneously with the nuclear reactions and weak decays that compose the nucleosynthesis process. The size of the model determines the time when neutron diffusion becomes significant. This article describes in detail how the time of neutron diffusion relative to the time of nucleosynthesis affects the final abundances of He4, deuterium and Li7. These results will be compared with the most recent observational constraints of He4, deuterium and Li7. This inhomogeneous model has He4 and deuterium constraints in concordance for baryon to photon ratio eta = (4.3 - 12.3) X 10^{-10} Li7 constraints are brought into concordance with the other isotope constraints by including a depletion factor as high as 5.9. These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.
 
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  • #2
wolram said:
http://arxiv.org/abs/astro-ph/0506364

Title: Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model
Authors: Juan F. Lara
Comments: accepted for publication in Physical Review D
......
These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.
Does that mean the standard BBN model has to be baryon homogeneous?

Garth
 
  • #3
I think yes, but I am not sure. The universe is homogeneous after inflation. Why should it be 'baryon inhomogeneous'?
 

1. What is neutron diffusion?

Neutron diffusion is the process by which neutrons move from areas of high concentration to areas of low concentration, typically within a nuclear reactor or other nuclear system.

2. How does neutron diffusion affect nucleosynthesis?

Neutron diffusion plays a critical role in the process of nucleosynthesis, which is the formation of heavier elements from lighter ones within stars. Neutron diffusion allows for the capture of neutrons by atomic nuclei, leading to the creation of new, heavier elements.

3. What factors influence neutron diffusion?

The diffusion of neutrons is influenced by a variety of factors, including the concentration and energy of the neutrons, the density and composition of the surrounding material, and the presence of any moderating materials that can slow down the neutrons.

4. Can neutron diffusion be controlled?

Yes, neutron diffusion can be controlled through various means, such as by using neutron-absorbing materials or by adjusting the geometry of the nuclear system. This control is crucial in maintaining a stable and safe nuclear reaction.

5. What is the significance of neutron diffusion and nucleosynthesis in understanding the universe?

Neutron diffusion and nucleosynthesis are fundamental processes in the formation and evolution of the universe. They are responsible for the creation of all elements beyond hydrogen and helium, which are essential for the existence of life. Studying these processes helps us understand the origins of the universe and the complexity of its components.

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