Can electrons knock out neutrons?

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Discussion Overview

The discussion revolves around the possibility of electrons knocking out neutrons from a nucleus, specifically comparing this process to that of protons and photons. It explores theoretical aspects, probabilities, and practical implications in the context of neutron production for medical isotopes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that while it is theoretically possible for electrons to knock out neutrons, the likelihood of this occurring is very low due to the neutron's lack of net charge.
  • One participant questions the probability of electron-induced neutron ejection compared to that of protons or gamma rays.
  • Another participant notes that protons interact with neutrons via the strong interaction, making the process of neutron ejection more probable with protons than with electrons.
  • There is a discussion about the feasibility of using high voltages to accelerate electrons for neutron production, with some participants mentioning that achieving the necessary energy levels (around 2 MeV) is possible.
  • Participants discuss historical and practical aspects of using Van de Graaff accelerators for high voltage applications, including concerns about arcing and containment.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and efficiency of using electrons versus protons for neutron production, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion includes assumptions about the interactions between charged particles and neutrons, as well as the technical challenges associated with achieving the necessary energy levels for electron acceleration.

Murdock
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I know that sufficiently energetic protons and photons (1.7MeV) can knock a neutron out of a beryllium nucleus. Can an electron do the same?
 
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In principle yes, but I would expect that the process is very unlikely as the neutron does not have a (net) charge.
 
What do you think the probability of it occurring would be compared to a a proton or gamma ray doing the same?
 
I don't know, but I guess someone studied it somewhere.
Why do you ask?
 
I was wondering because a commonly used neutron source is to use high voltages to accelerate protons into a target to produce neutrons for breeding medical isotopes. It just seemed to me you should be able to skip the "middle man" and get a higher efficiency out of it.
 
How do you skip something if you replace protons by electrons?
Protons interact with neutrons via the strong interaction, that makes the process much more likely.
 
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Interesting question since photons don't represent a net charge or capture mechanism.
Then again, I don't know if acceleration process is simple and easy when you have to deliver almost 2 MeV.
 
2 MeV is possible with DC acceleration. With protons you can even save 1 MV of high voltage because you can start with negatively charged ions and use the acceleration voltage twice.
 
mfb,
Agreed. Back in the days Van De Grafs were used, millions of volts were routinely developed. Then again, they were pressed into using high pressure containment to mitigate arcing. It does beg the question, what is a reasonable voltage for commercial use?
 
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I don't know if commercial applications use DC accelerators, but I know those do exist in this energy range.
 
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Mike_In_Plano said:
mfb,
Agreed. Back in the days Van De Grafs were used, millions of volts were routinely developed. Then again, they were pressed into using high pressure containment to mitigate arcing. It does beg the question, what is a reasonable voltage for commercial use?

Hmpf! I'm sitting in the control room of a Van de Graaff accelerator that is in use right now. "Back in the days" indeed.
 
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