Solve Bethe Formula: Find dE/dx Units for Particle in Material

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Discussion Overview

The discussion revolves around the application of the Bethe formula to calculate the stopping power (dE/dx) of a particle as it traverses a material. Participants are focusing on unit conversions and specific terms within the formula, particularly the delta term.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant expresses confusion regarding the units in the Bethe formula, specifically questioning how to convert the term involving (e^2/4PiEpsilon) from J*m to MeV*cm.
  • Another participant suggests that the Wikipedia formula may be suspicious and recommends consulting the particle data book for potentially more reliable coefficients.
  • A participant seeks clarification on how to determine the appropriate value for the delta term in the equation, particularly in the context of high-energy scenarios.
  • It is noted that the delta term is defined in a specific section of the particle data book, and that its effect is minimal for \beta\gamma values less than 10.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the reliability of the Wikipedia formula versus the particle data book, and there is ongoing uncertainty regarding the delta term and its implications.

Contextual Notes

Participants reference specific sections of the particle data book for definitions and coefficients, indicating that the discussion may depend on these external resources for clarity on certain terms.

Who May Find This Useful

Individuals interested in particle physics, particularly those working on calculations involving particle interactions with matter and the Bethe formula.

jbb88
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Im trying to use the Bethe formula (http://en.wikipedia.org/wiki/Bethe_formula) to find dE/dx for a particle through a material, but I am not getting the units to work out. In the part of the formula with (e^2/4PiEpsilon)^2, how should I convert this correctly? Those units are J*m, so can I just multiply by 100 to get it to J*cm and divide by 1x10^-6 to get it into MeV*cm?
 
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At first glance, wikipedia's formula looks suspicious, although they may be equivalent, I always use : the particle data book
You may find your coefficient in table 27.1 if you really want wikipedia's formula.
 
Thanks, ill use that. The one thing I am not sure of is the delta part of that equation. How do I figure out what to use for delta(beta gamma)?
 
If you need this term at high energy, it is defined (and discussed) in 27.2.2
Also, look at "without delta" curve label in 27.1
For \beta\gamma<10 the effect is rather small
 

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