Discussion about possible ECAL/HCAL in 2026

Wednesday 12 Mar 2025, 13:00 → 14:35 Europe/Zurich

13:00 → 13:10 Brief introduction

Speaker: Hidetoshi Otono (Kyushu University (JP))

Introduction

Objective:

• The primary goal is to install the AHCAL detector during the winter shutdown period between 2025 and 2026 to:
  • Gather valuable data from 2026.
  • Provide essential input for upgrades in the next round of detectors (Run4).

Installation and Logistics Planning

• Detector Specifications and Challenges:

  • The AHCAL detector has a significant weight of approximately 5 tons.
  • Due to crane limitations, the detector may need to be shipped as a whole unit, then disassembled and reassembled at the installation site.

• Installation Timeline:

  • There is a narrow time window available during the winter shutdown between 2025 and 2026.
  • Discussions mentioned potential installation windows:
    • Mid-December or early January for tunnel installation.
    • Surface commissioning planned at a designated site (EHN1) starting around September.
  • Shipping from China is tentatively scheduled for the end of June or the beginning of July, allowing for 2–3 months of commissioning prior to installation.

• Logistical Considerations:

  • Transportation challenges include ensuring safe handling of the heavy detector and managing the additional shielding needed near the beam pipe.
  • Coordination between USTC, CERN, and Japanese teams is necessary to finalize the schedule and logistics.

Commissioning Discussion

• Commissioning Strategy:

  • The discussion emphasized the importance of starting commissioning as soon as possible, even if not all teams can be present on day one.
  • There was a suggestion that the commissioning should be initiated at USTC, with some teams joining later due to scheduling constraints (notably, Japanese fiscal year considerations may delay full participation until April).

13:10 → 13:30 AHCAL beam tests results

Speaker: Hongbin Diao (USTC)

Simulation and Validation of AHCAL.pdf

Simulation and Validation of AHCAL.pptx

AHCAL Beam Test Results

• Overview of the Presentation:

  • introduced his simulation work and validation for the AHCAL prototype.

• Prototype and Simulation Setup:

  • He described the design of the prototype, which includes a 72×72 array configuration with 40 layers.
  • The simulation geometry covers key elements such as the active layers, absorber materials, and overall detector dimensions.
  • The prototype and simulation setup are used to evaluate energy deposits and the subsequent digital signal generation.

• Performance Evaluation:

  • The simulation results, including the energy reconstruction and event selection criteria, indicate that the beam test data (from MIP signals and hadron showers) are being reproduced within acceptable limits.
  • The test results validate that, despite the noted issues, the current simulation framework is capable of extracting meaningful performance metrics from the prototype.

• Conclusion and Next Steps:

  • Concluded that further calibration and correction (especially addressing the SiPM parameter bug) will enhance the precision of the simulation.
  • The next steps include refining the digitization process and integrating improved calibration methods to ensure that the simulation accurately reflects the beam test outcomes.
  • These improvements are critical for predicting detector performance for future neutrino measurements and overall detector upgrades.

13:30 → 13:50 Simulation update

Speaker: Yasuhiro Maruya (Institute of Science Tokyo (JP))

Yasu_offaxisdetector_sciWAHCAL_20250312.pdf

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.

13:50 → 14:10 Discussion

Conclusions and Next Steps

• Action Items:

  • Finalize the commissioning schedule with a detailed timeline for installation and service testing.
  • Resolve technical issues in the simulation, particularly in the SiPM/digitization.
  • Further evaluate data transfer requirements based on the detailed simulation of event sizes and trigger rates.
  • A follow-up document is expected to be shared, summarizing the meeting discussions and next steps.

• Team Coordination:

  • Continuous coordination among USTC, CERN, and Japanese teams is critical to align scheduling and technical implementations.
  • Special attention is needed for logistical challenges such as transportation, reassembly, and additional shielding near the beam pipe.