Study signal under different targets

[tvami]

Issue description

We are considering to run with Aluminium and Titanium targets instead of the Tungsten

Tasks

• This mostly is relevant as the mass of the "target" in the MadGraph, so change the numbers to the one for Aluminium
• Same but for Titanium
• Compare all these three options at LHE level
• Compare them at ldmx-sw level

Existing material to start off

• Prev MadGraph issues