Units of Electron Volts (AMeV)

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SUMMARY

The discussion centers on the unit AMeV, commonly used in space weather publications to denote energy per nucleon. The "A" represents the mass number of a nucleus, indicating that a Carbon nucleus with 1 AMeV has a total energy of 12 MeV, as A=12 for Carbon. The unit AMeV is crucial for understanding nuclear reactions, as it provides a standardized measure of energy per nucleon, despite some confusion in notation across literature. Authors often omit the space between "A" and "MeV," leading to inconsistencies in representation.

PREREQUISITES
  • Understanding of nuclear physics concepts, specifically mass number and atomic number.
  • Familiarity with energy units, particularly electron volts (eV) and mega-electron volts (MeV).
  • Knowledge of nuclear reactions and their significance in particle physics.
  • Awareness of notation conventions in scientific literature.
NEXT STEPS
  • Research the significance of energy per nucleon in nuclear physics.
  • Explore the differences between mass number and atomic number in nuclear reactions.
  • Investigate the notation standards in scientific publications, particularly in particle physics.
  • Read about the applications of AMeV in space weather studies and nuclear energy assessments.
USEFUL FOR

Researchers in nuclear physics, students studying particle physics, and professionals involved in space weather analysis will benefit from this discussion on the AMeV unit and its implications in scientific literature.

GreenLRan
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Hi,
I have been viewing some publications related to space weather and have noticed that in many graphs and in the articles, the units AMeV appear very often. I am wondering what the A is for?

My best guess is that means atomic, ie relating energies of ions rather than single electrons. Does anyone know for certain. If so, can you provide proof or documentation?

Thank you!
 
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A is the mass number of a nucleus. So if a Carbon nuclei has 1 A MeV, it has a total energy of 12 MeV since A=12 for Carbon.
 
That's weird. If an eV is the energy of a single electronic charge which has been accelerated across 1V PD then it will be the same for all singly charged objects. If the atom is multiply ionised then the energy would be higher, natch, but would it not relate to the Atomic (Proton) Number, rather than the Mass Number? (The Neutrons are not accelerated by the V, after all)
All this is only applicable under pretty extreme generating conditions, I guess.
 
hi Norman,
is there any book explain it. because i notice in particle physics journal many author ref it as AMev or AMeV, without a space between A/A and MeV. I also just curious about this unit confusion..
thanks
 
sophiecentaur said:
That's weird. If an eV is the energy of a single electronic charge which has been accelerated across 1V PD then it will be the same for all singly charged objects. If the atom is multiply ionised then the energy would be higher, natch, but would it not relate to the Atomic (Proton) Number, rather than the Mass Number? (The Neutrons are not accelerated by the V, after all)
All this is only applicable under pretty extreme generating conditions, I guess.

I think the rational for AMeV units is that it gives the energy-per-nucleon, an important quantity to know for nuclear reactions. For example a 12 MeV C-12 nucleus is comparable to a 56 MeV Fe-56 nucleus. Different total energies, but each has the same 1 AMeV.
 
Rajini said:
hi Norman,
is there any book explain it. because i notice in particle physics journal many author ref it as AMev or AMeV, without a space between A/A and MeV. I also just curious about this unit confusion..
thanks

I don't know of any books off hand that cover the subject (there might be some older nuclear physics books that I am not familiar with that look at it). Much of your confusion is simply sloppy notation which is very common the physics literature and which I am often guilty of. Typically there is no space between the A and MeV. And whether A is italicized or not is likely due to whether the author is using italic letters to denote variables or not.
 
So does that mean that this unit have been better expressed as MeV/A ?
 

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