Spontaneous fission experimental discrepancy

[slipforever]

Spontaneous fission experimental discrepancy!

Hi, I've been studying the book "Nuclear Physics- Principles and Applications" by John Lilley and I've come into a problem with the reason for the discrepency between experiment values for the activation value and the mathmatical one from the SEMF.

an even-even nucleus undergoes symmetric fission by disintegrating into two identical even-even nuclei.
considering only the surface and the coulomb terms of the SEMF why is the fissility parameter Z^2/A greater in experiment than in the math one??

ANyone?!
Thanks

 

[AndyW]

for bringing up this interesting question. As a nuclear physicist, I have also encountered this discrepancy in experimental values for spontaneous fission. To answer your question, we need to understand the concept of fissility and the factors that affect it.

Fissility is a measure of how easily a nucleus can undergo fission. It is determined by the ratio of the Coulomb energy to the surface energy in the SEMF. The higher the fissility parameter (Z^2/A), the more easily a nucleus can undergo fission. However, the experimental value for fissility is often higher than the theoretical value calculated from the SEMF.

One possible explanation for this discrepancy is that the SEMF does not take into account all the factors that affect fissility. For example, the SEMF assumes that the nucleus is a perfect sphere, but in reality, nuclei are not perfectly spherical. This can affect the surface energy and therefore the fissility parameter.

Additionally, the SEMF does not consider the effects of nuclear shell structure on fissility. In certain nuclei, the presence of magic numbers (nucleon numbers with high stability) can make them less likely to undergo fission. This is not taken into account in the SEMF and can contribute to the higher experimental values for fissility.

Other factors such as nuclear shape, angular momentum, and nuclear excitation energy can also affect the fissility of a nucleus and are not considered in the SEMF.

In conclusion, the discrepancy between experimental and theoretical values for fissility can be attributed to the limitations of the SEMF in accurately predicting all the factors that affect fissility. Further research and experiments are needed to fully understand and explain this discrepancy. I hope this helps to answer your question.

 

[sir-pinski]

for bringing up this interesting question! The discrepancy between experimental values for spontaneous fission and the theoretical values predicted by the SEMF (Semi-Empirical Mass Formula) has been a topic of discussion and research for many years.

There are a few possible explanations for this discrepancy. One potential factor is that the SEMF is a simplified model and does not take into account all the complexities and nuances of nuclear fission. For example, it does not consider the effects of shell structure and nuclear deformation, which can significantly impact the fissility parameter.

Another factor could be experimental limitations and uncertainties. Measuring the exact values of nuclear properties, such as the activation energy, is a challenging task and can be affected by various sources of error. This could lead to discrepancies between experimental and theoretical values.

Additionally, there may be other factors at play that are not yet fully understood. Nuclear fission is a complex process and there could be other underlying factors that contribute to the observed discrepancy.

Further research and experimentation are needed to fully understand and reconcile the differences between experimental and theoretical values for spontaneous fission. It is an ongoing and dynamic area of study in nuclear physics, and I'm sure there will be many more insights and developments in the future.