link to lecture transcript - UT-H GSBS Medical Physics Class Site

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We also observe there are peaks in dσ/dE at both zero energy and the maximum energy. Low energy and high energy electrons are more likely than medium energy electrons. Notice, for example, for a high energy incident photon the differential energy cross section is relatively flat but as you get to the maximum energy you have a peak. For very low energy photons we find there is a significant decrease in differential cross section as we increase the energy. We observe a distinct minimum in the energy distribution of the scattered electrons and then again a peak. 24
We can always calculate what the maximum electron energy is from the Compton equation; this is the quantity that we call a Compton edge, an observed increase in the energy distribution of the scattered electrons. So if we are able to look at the scattered electron energy distribution using some kind of multi-channel analyzers or something like that we will find there’s going to be a peak right at the maximum energy. This maximum is called the Compton edge. I think you are going to be seeing Compton edges in subsequent courses when we talk about scintillation detectors. 25
Page 1 and 2: Today, we continue our talk about C
Page 3 and 4: We previously derived an equation f
Page 5 and 6: So σ 0 is the classical cross sect
Page 7 and 8: Let’s look at this graph. Notice
Page 9 and 10: What about the dependence of the Co
Page 11 and 12: The energy transferred to the elect
Page 13 and 14: If we plot the energy transfer coef
Page 15 and 16: The energy transfer coefficient has
Page 17 and 18: What about the scatter coefficient?
Page 19 and 20: Using this equation we can now plot
Page 21 and 22: This probability is represented by
Page 23: This figure is a plot taken from Jo
Page 27 and 28: Remember dσ/dE is relatively const
Page 29 and 30: Now we also look at the graph and s
Page 31 and 32: First, let’s recall that the atte
Page 33 and 34: What we now want to find out is how
Page 35 and 36: So far, our approximations have bee
Page 37 and 38: These values were tabulated by Hubb
Page 39 and 40: So what is the effect of binding en
Page 41 and 42: At higher energies there is no diff
Page 43 and 44: Note that this graph is for very lo
Page 45: The fraction of energy transferred

link to lecture transcript - UT-H GSBS Medical Physics Class Site

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