Allow the usage of "direct" extrapolation for Fast Electron like offline/HLT

Allow to use direct extrapolation for Fast Electron like offline/HLT.

Can be enabled by setting useCaloInfoInExtrap to true

Gaudi::Property<bool> m_useCaloInfoInExtrap{
        this, "useCaloInfoInExtrap", false,
        "use knowledge of the cluster in extrapolation"};

Perhaps some expanations are in order.

In offline/HLT (they are the same code ) over the last couple of years we moved to a "direct" extrapolation to the known sampling (known since we target a specific cluster not something "arbitrary" so we have a "constrain").

More specifically the "caloExtension" method call it A (that is used in the Fast Electron Re Algo) does :

1. An extrapolation all the way to the exit of the calo (so quite a bit of distance we do not need, EMB3 and full hadronic ...)
2. While doing "navigation" as does not target a specific surface, but need to find where it goes.
3. Doing muon material effect (in principle the electron has most probably showered somewhere soon after entry so we do not track a "single particle")

Although none of the above are "wrong"...

The problem we have is more like "please extrapolate directly to a surface somewhere in the middle of the second sampling given this cluster".

• So no need to go all the way out and then use just one intersection.
• No need to do navigation to figure where we go
• No need to do multiple scattering in the full calo volume.

Since a couple of years we can do just this (we could also do it 6-8 years ago but lets say the ability was lost at some point between ...) So call that caloExtension method B make a surface and target it "directly"...

• I can have very well have nuked this implementation ... (i.e will not run will nuke the ouput beyond recognition)
• Even if not since we match in a window I kind of doubt we will have binary equility so some counts will change somewhere.
• One naively would prb expect something like +/-1 in the relevant "steps" (like some edge effect or extrapolations getting lost for low pt tracks in the older way)

Anyhow @damazio @eegidiop this is what I meant this can be done much faster and like offline/HLT.

Ping also @safarzad and @sutt (as asking me what we do to match calo is one of his "usual" ;) )

I do not have the full "machinery" for this part of out code. By faster here I have seen more 2x-3x in offline/HLT. And offline/HLT use this caloExtension method so ...