Particle energies after beta decay in different frames

In summary, the conversation discusses the maximum energy of an electron after the \beta-decay of neutrons. It is noted that while some sources state a maximum energy of less than 800 keV, other studies using Monte Carlo codes allow for higher energies. This is attributed to different frames of reference. The conversation also mentions calculating the maximum electron energy from a 100 MeV neutron in the lab frame, which would require applying the principles of special relativity.
  • #1
gr1979
1
0
Hi,

I am reading in some books that after the [itex]\beta[/itex]-decay of neutrons, the maximum energy of the resulting electron is a bit less than 800 keV. In some cases, however, I see that in e.g. some studies that try to extract the electron energy from [itex]\beta[/itex]-decay of neutrons with some Monte Carlo codes, they allow for the energy of the electron to acquire much higher values. Do I suspect correctly that this possibly due to different frames of reference?

How can I calculate the maximum electron energy from a decay of e.g. a 100 MeV neutron in the lab frame?
 
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  • #2
gr1979 said:
Hi,

I am reading in some books that after the [itex]\beta[/itex]-decay of neutrons, the maximum energy of the resulting electron is a bit less than 800 keV. In some cases, however, I see that in e.g. some studies that try to extract the electron energy from [itex]\beta[/itex]-decay of neutrons with some Monte Carlo codes, they allow for the energy of the electron to acquire much higher values. Do I suspect correctly that this possibly due to different frames of reference?

How can I calculate the maximum electron energy from a decay of e.g. a 100 MeV neutron in the lab frame?
Is one referring to free neutrons, as opposed to neutrons in a nucleus.

This presentation gives a cutoff of 782 keV (I'm assuming thermal or cold neutrons near rest)
http://www.jlab.org/Hall-C/talks/08_09_07/martin.pdf (slide 16) Slide 21 has some neutron energy spectra.
The maximum beta energy is given as 782 keV +/- 13 keV in -
http://socrates.berkeley.edu/~phylabs/adv/ReprintsPDF/BRA%20Reprints/03%20-%20Beta%20Decay.pdf

If a neutron has an initial kinetic energy, then that energy would be partitioned to the proton, electron and antineutrino following decay. Apply conservation of energy and momentum.

A terrestrially produced 100 MeV neutron would require a high energy spallation source.
 
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  • #3
gr1979 said:
Do I suspect correctly that this possibly due to different frames of reference?
Right. The energy of a particle is always frame-dependent.

How can I calculate the maximum electron energy from a decay of e.g. a 100 MeV neutron in the lab frame?
With special relativity, see this topic for a similar question. I would expect a value of ~900 keV as maximal energy.
 

Related to Particle energies after beta decay in different frames

1. What is beta decay?

Beta decay is a type of radioactive decay in which a nucleus emits a beta particle (an electron or positron) in order to achieve a more stable state.

2. How does beta decay affect particle energies in different frames?

In beta decay, the emitted beta particle carries away some of the energy from the decaying nucleus. This can result in a change in the particle's energy depending on the frame of reference in which it is observed. In some frames, the particle's energy may appear to increase, while in others it may appear to decrease.

3. What are the different frames used to observe particle energies after beta decay?

The two most commonly used frames to observe particle energies after beta decay are the rest frame of the decaying nucleus and the center-of-mass frame of the decaying system. In the rest frame of the nucleus, the particle's energy may appear to increase, while in the center-of-mass frame, it may appear to decrease.

4. How do relativistic effects play a role in particle energies after beta decay?

Relativistic effects, such as time dilation and length contraction, can impact the observed energy of a particle in different frames. These effects become more significant at higher energies, so they are particularly important to consider in the context of beta decay, which often involves high-energy particles.

5. Are there any other factors that can influence particle energies after beta decay?

Other factors that can affect particle energies after beta decay include the mass of the decaying nucleus and the type of beta decay (beta-minus or beta-plus). The energy of the emitted beta particle can also vary depending on the specific decay process and the properties of the particles involved.

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