September 18, 2020 Meeting Minutes

Post-meeting notes

Need to do a "backwards" calculation to reproduce the measured radiation signal. That is, electron beam creates ions, which impact the PC and produce SEY, which hit the gun chamber/beam pipe and produce radiation -- for a given electron beam current, what is the radiation rate?
PIXE X-rays from Gallium and Arsenic, while they exist, cannot penetrate the thickness of the gun chamber and beam pipe and thus, cannot be detected by the radiation monitors...or at least it is extremely unlikely that they will.
Carlos presented a plot of the gamma ray sensitivity of the radiation monitors - need a graph of counts per second vs gamma-ray (or X-ray) energy.
Cristhian presented IBSimu simulations of an SEY beam. For 1-to-1 SEY, some secondary electrons hit the anode, bounce back to the cathode, then to the gun chamber, etc. This suggests that, while this form of "containment" of secondary electrons in the gun chamber is rare and short lived and the real SEY is below 1, it may become important: even if the probability of a "contained" SEY is 0.01%, a primary beam of billions of electrons could still create thousands of contained SEY.