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

More documents

Recommendations

Info

So 3.16 10 27 electrons per meter squared times the Compton coefficient times the number of incident photons gives us the number of photons that are scattered. The result is 9.14 10 2 photons. We find the assumption of a thin absorber is reasonable in this case. So now we kknow hhow many electrons l t are scattered. tt d 32
What we now want to find out is how many electrons have energies between 0.15 and 0.25 MeV. What is the differential cross section for photons of incident energy ½ MeV producing electrons of energy around 0.2 MeV? We find the differential scatter cross section is roughly 70 10 -30 meters squared per electron per MeV. That’s a ballpark figure. Again, we’re estimating here. We will not do an exact calculation. To do the exact calculation you would have to plug and chug into the equation for differential cross section, which I am not going to have you to do. 33
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 and 24: This figure is a plot taken from Jo
Page 25 and 26: We can always calculate what the ma
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: First, let’s recall that the atte
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

Create successful ePaper yourself

Delete template?

Save as template?