gFEX Jet Algo Updates

With this MR, major updates of the gFEX simulation, and in particular the jet finder algorithm, are included to reproduce what is in the gFEX firmware. The required changes are documented in ATLGFEX-124 and in this presentation, where a better agreement between TOBs from data and emulated ones is shown after the updates.

More specifically, the main changes are the following:

• Combine the two halves of the FPGA-C gTower input (forward-negative and forward-positive) into one matrix with the correct format (12x32 towers) as done in the firmware, and as required by the jet algorithm;
• Update the calculation of the large-R jets when including partial sums from towers of adjacent FPGAs;
• Update pile-up calculation, including a look-up table as in the firmware, and use gTowers with 50 MeV resolution (saved in the input ByteStream decoder) as input to the calculation (as opposed to the default 200 MeV towers).