Orsay results: effect of target thickness and Q calculation method on resolution

(Everything here assumes the detector configuration C discussed below, and a 1 mm diameter beam spot.)
First, use 10 μg/cm² target, and compare different ways of calculating the Q-value: use the measured energies for both alphas and the ¹⁸O, and also deduce the ¹⁸O energy from the measured alpha energies. results:

It's clearly better to just use ¹⁸O as a tag, and not attach any significance to its measured energy, since it's subject to a lot of energy loss/straggling in the target (even at 10 μg/cm²). All cool.

Now compare two target thicknesses: 10 μg/cm² and 100 μg/cm². Use the alphas-only Q-value calculation method. results:

What that says to me is that even at 100 μg/cm² it should be possible to see the presence of the 6.351 MeV level: the difference in energies/Q values is about 55 keV, and at 100 μg/cm² the peak width is about 51 keV (while at 10 μg/cm² it's only about 30 keV)--so if the 6.351 MeV level is populated, it will either produce a tail on the 6.404 peak or will broaden it noticeably.

Comments? Thoughts?

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