--text from email--
Using Claudia's code, I added a layer of Al foil before the heavy ion
silicon detector.  The attached plots correspond to the heavy ion
portion of fig 3(a) in the proposal.  Thus it only uses ground-state
transitions and doesn't account for geometry or efficiency etc.  I opt
to show only the highest and lowest beam energies for each simulation.

As I said before, something between 10 and 20 um of Al was likely to
be the correct choice, which is confirmed.  10 um is almost to thin to
guarantee the signals are below 200 MeV, while for 20 um we start
having issues of detecting the lowest energy recoils for the low
energy run.

We can discuss the selection in more detail at the next meeting, but
most probably we can just use some kitchen foil, adopting whatever its
thickness of 13 to 15 um depending what we find.

The attached file starts with no degrader, then adds 10 um Al, and 1
um Al steps up to 20 um.