1. Jan 27, 2012

### m3h

1. The problem statement, all variables and given/known data

I need to estimate the energy loss of electrons before they reach a detector, but I am unsure how to do it. I think I am supposed to integrate the stopping power function over the total distance but I can't solve the equation...

2. Relevant equations

Stopping power=-dE/dx

Energy loss=∫-dE/dx (I think)

3. The attempt at a solution

Is the solution - e*x?

Any help is appreciated!

2. Jan 27, 2012

### BruceW

That is the stopping power, but for the energy loss, you've forgotten to write dx, to show what variable you are integrating over. And about the solution, the stopping power will depend on the energy of the particle, and the medium its going through, etc, so you'll need to use a particular model to find a solution. This might be useful: http://en.wikipedia.org/wiki/Stopping_power_(particle_radiation [Broken])

Last edited by a moderator: May 5, 2017
3. Jan 30, 2012

### m3h

Yes. that's the article I first looked at, specifically "The deposited energy can be obtained by integrating the stopping power over the entire path length of the ion when it moves in the solid."

When you said I needed to add dx, did you mean I should write ∫(dE/dx)dx? Doesn't dx disappear then?

Shouldn't it be enough to solve the diff equation above?

4. Jan 30, 2012

### BruceW

Yes, you should write it like that. The idea is that you know something about dE/dx, so then you integrate it to get the change in energy.
And you're right that you could make the dx disappear, which just tells us that the change in energy is equal to the change in energy (as we would expect).

5. Jan 30, 2012

### m3h

Ok, thank you. I think I know what to do now.

Thanks for the help!

6. Jan 30, 2012

### BruceW

yep, glad if i've helped a bit