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Here is one example of event visualization: A hypothetical particle (Z') with the mass 40 TeV decays to W+ and W- bosons. Such heavy particles can only be produced at the FCC-hh experiment with the center-of-mass of energy of 100 TeV for colliding protons. The transverse momenta of these bosons from the Z' decay is about 20 TeV. Here are a few images illustrating a single event Z'(40 TeV) → W+W- → hadrons:
This simulation was created using a FCC-like detector (SiFCC) developed at ANL/Fermilab/Duke. This detector is described here. The Monte Carlo sample used for this simulation is available from the HepSim repository.
You can see two high-pT jets (~20 TeV) from each W decay, and many back-splash particles. This event has many secondary interaction in the detector material. These images show Geant4 truth-level particles (straight lines) created by secondary interactions due to “back-splash” events.
A real pp (100 TeV) → Z'(40) → W+W- is expected to be more complicated due to the presence of the protons in the initial state and pileup events (up to 1000 MinBias events).
This simulation is very challenging since the SiFCC(v4) detector has high-granularity calorimeters with more than 150 million cells. For example, the HCAL (TileCal) of the ATLAS experiment has about 5000 cells (3 layers), while SiFCC has 50 million cells (64 layers). The simulation of a single event like this in the SiFCC(v4) detector takes 4 hours (8 CPU cores, Xeon(R) CPU E5-2450 2.50GHz) with 16 GB memory on the ANL/HEP cluster. The simulation of a typical pp-collision event at the LHC takes 15 min.
The event shown above has:
- 10,000 hits in ECAL
- 46,000 hits in HCAL
- 12,000 hits in the outer tracker
- 1,000 hits in the inner tracker
This is another Z'(40 TeV) → W+ W- example, where W+ decays to hadrons, and W- decays to electron and neutrino. The neutrino is not detected, but the electron can be well reconstructed as shown here:
This event has 25,000 hits in the HCAL+ECAL, and about 6,000 in the tracker.
How to make such images
Use Jas4pp as:
wget http://atlaswww.hep.anl.gov/asc/jas4pp/download/current.php -O jas4pp.tgz tar -zvxf jas4pp.tgz cd jas4pp source ./setup.sh # takes 5 sec for first-time optimization wget http://mc.hep.anl.gov/asc/hepsim/events/mumu/40tev/mm40tev_pythia6_zprime_ww/rfull006/tev40mm_pythia6_zprime40tev_ww_0036_pandora.slcio jaspp tev40mm_pythia6_zprime40tev_ww_0036_pandora.slcio
Then press the small “run” (blue arrow) button on the toolbar. Then go to File → New → Wired 4 View. The you should wait for 5-10 before the image will appear. The first event from this file is what you see in the above images. You will need a computer with at least 8 GB RAM.
You can download all reconstructed files as
Physics studies used this detector were discussed in the talk Simulation of a high-granular hadronic calorimeter for multi-TeV physics.
— Sergei Chekanov 2016/04/29 16:23