Simulation and Digitization Updates

• Simulation Overview:

  • Event Rate Estimation:
    • The maximum expected muon event rate from the ATLAS interaction point is estimated at around 3.1 kHz.
    • This high rate is primarily due to the muon flux measured using emulsion films.
  • Neutrino Backgrounds:
    • The simulation addresses neutrino-induced backgrounds.
    • A CNN-based Particle Identification (PID) is employed:
      • Approximately 40% efficiency for νₑCC events.
      • About 97% rejection for ν_μCC and neutral current (NC) events.

• Digitization Process:

  • Energy Deposit to Signal Conversion:
    • Energy deposits over a 150 ns window are summed.
    • The summed energy is converted into a number of photons using a calibrated factor.
    • A SiPM response function converts the photon count into the number of pixels that react.
  • A notable issue was identified:
    • • A bug where the SiPM values from layers 38 and 39 were used universally for all layers.
      • This affects the saturation characteristics and dynamic range, especially since SiPMs below layer 38 saturate at lower energy (around 140 MeV).
    • A fix for this bug is planned to enable channel-by-channel digitization for improved accuracy.

Technical Q&A and Detailed Discussions

• Trigger and Readout Systems:

  • Technical clarifications were made regarding the trigger board:
    • The trigger system utilizes separate scintillator counters to generate trigger signals.
    • High-gain and low-gain channels are managed differently; the low-gain channel is primarily used for high-energy events.
  • Data transfer challenges include:
    • Installing network switches in the tunnel.
    • Ensuring that the servers installed in high-radiation areas are adequately shielded.

• SiPM and Saturation Concerns:

  • The technical discussion focused on:
    • The importance of accurate SiPM calibration.
    • The impact of saturation on energy resolution, particularly for high-energy neutrino events.
    • The need to adjust the digitization model to reflect the different dynamic ranges of SiPMs in various layers.