MuonBack

Analysis of the Muon Background for the SHiP experiment, focused on hit rates in the Surrounding Background Tagger (SBT).

The goal is to reconstruct simulation files from Guglielmo Frisell's TRY 2025 production and compute SBT hit rates as a function of energy threshold — for comparison with results from the 2018 production (Anupama Karmakar).

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Repository Structure

MuonBack/
├── Production/    # HTCondor job submission and reconstruction
└── Inspection/    # SBT hit rate analysis and output

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Production

Runs ShipReco.py (FairShip) on simulation files via HTCondor on lxplus. Each job takes one simulation file, reconstructs it, and copies the output to EOS.

Input

Simulation files from Guglielmo Frisell's TRY 2025 production on EOS:

/eos/experiment/ship/user/gfrisell/Simulation_Results/TRY_2025_EM/<job_dir>/sim_<uuid>.root

Each job directory also contains:

• geo_<uuid>.root — geometry file
• params_<uuid>.root — parameter file
• simRunOutput_2.txt — simulation run log

The full list of input simulation files is in Production/input_files.txt (~1000 files).
A short test list (5 files) is in Production/input_files_short.txt.

Output

Reconstructed files are written to EOS at:

/eos/user/j/jaweiss/MuonBack/job_<job_dir>/

Each output folder contains:

• sim_<uuid>.root — original simulation file (copy)
• geo_<uuid>.root — geometry file (copy)
• params_<uuid>.root — parameter file (copy)
• reco_<uuid>.root — reconstruction output (ship_reco_sim tree)
• simRunOutput_2.txt — simulation run log

Files

File	Description
muonback.sub	HTCondor submission file
submitscript3.sh	Worker node script: loads FairShip, runs ShipReco.py, copies output to EOS
config_fairship.sh	FairShip environment configuration
input_files.txt	Full list of ~1000 simulation files
input_files_short.txt	Short list of 5 files for testing
logs/	HTCondor job logs (gitignored)

How to Submit Jobs

Test run (5 files):

cd Production/
# make sure input_files_short.txt is set in muonback.sub:
# queue SIM_FILE from input_files_short.txt
condor_submit muonback.sub

Full production (~1000 files):

cd Production/
# make sure input_files.txt is set in muonback.sub:
# queue SIM_FILE from input_files.txt
condor_submit muonback.sub

Monitor jobs:

condor_q -submitter jaweiss
condor_history -submitter jaweiss | head -20   # check completed/removed jobs

HTCondor Configuration

Setting	Value
CPUs	1
Memory	4 GB
Disk	5 GB
Job flavour	espresso (~20 min, sufficient per job)
Max retries	3
OS	AlmaLinux9
FairShip version	26.04/latest via CVMFS

Jobs are removed after 3 failed attempts (on_exit_remove). Failed jobs can be inspected via condor_history.

ShipReco.py Arguments

ShipReco.py accepts the following optional arguments. None of them were used in this production — all defaults apply.

Argument	Default	Description
--noVertexing	off	Skips the vertexing step (2-track vertex reconstruction). Not needed for SBT hit rate analysis, which uses only MCTrack and vetoPoint from the simulation tree.
--noStrawSmearing	off	Disables distance-to-wire smearing in the straw tracker. Relevant for tracking performance studies, not for SBT analysis.
--withT0	off	Simulates an arbitrary T0 offset and corrects for it. Relevant for timing studies.
--patRec	AR	Pattern recognition algorithm: AR (Artificial Retina, default), FH (Hough transform), or TemplateMatching. Not passing this argument does not skip pattern recognition — Artificial Retina runs by default.
-dy	from filename	Maximum tank height in cm. Extracted automatically from the input file name if not given.
--firstEvent	0	Index of the first event to process.

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Inspection

Computes SBT hit rates from the reconstructed and simulation files stored on EOS.

What it does

inspect_Back.py loops over all job output folders in /eos/user/j/jaweiss/MuonBack/, loads the cbmsim tree from each simulation file and the ship_reco_sim tree from each reco file (used only for event ID synchronisation), and fills histograms of:

• vetoPoint energy deposition per particle, PDG composition, spatial topology (z, φ)
• Digitised SBT hits at thresholds of 0, 10, 20, 30, 45, 50, 60, 90 MeV:
  • Total hit rate (MHz) and maximum per-cell rate (Hz)
  • Hit multiplicity per event
  • Energy deposition distributions
  • z–φ topology maps

Event weights from MCTrack are applied throughout to scale generated events to one SHiP spill.

Input

/eos/user/j/jaweiss/MuonBack/job_<job_dir>/
    sim_<uuid>.root   →  cbmsim tree  (MCTrack, vetoPoint)
    reco_<uuid>.root  →  ship_reco_sim tree  (ShipEventHeader only)
    geo_<uuid>.root   →  FAIRGeom + ShipGeo

Output

File	Description
inspection.root	ROOT file with all histograms
file_inspection_summary.txt	Plain-text summary of hit rates per threshold

How to Run

cd Inspection/
python inspect_Back.py --path /eos/user/j/jaweiss/MuonBack

Requires FairShip environment (run on lxplus after sourcing CVMFS setup).

Results (2018 production, propagation with TRY Muon shield)

to be added

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Dependencies

• FairShip (via CVMFS: /cvmfs/ship.cern.ch/26.04/)
• ROOT (included in FairShip environment)
• HTCondor (lxplus)
• EOS access (CERN account with valid Kerberos ticket)