The transportation team has provided the dimensional limits of the transport platform:
Width: 1000 mm
Length: 3000 mm
Height: 900 mm
The current AHCAL structure exceeds these limits slightly.
Larger Transport Platform:
Would require new design and verification by civil engineering.
Long lead time (previous example: 3 months).
Estimated cost over 10k CHF?
Rebuild the Frame:
The current frame holds 40 layers and is not disassemblable.
Remaking the frame would be costly and time-consuming.
Modify the Existing Frame:
Mechanical feasibility under investigation.
May involve reducing frame thickness or trimming corners.
Preliminary feedback suggests this is technically challenging.
Custom Cradle:
Proposed to build a simpler cradle with lifting points 1.8 meters apart.
Should support the frame (without iron plates).
Target weight under 2 tons.
Could be manufactured locally in China to reduce cost.
Shunliang? to provide detailed photos of the frame and potential lifting points.
USTC mechanical engineers to evaluate the cradle design.
The TLU board accepts 6 inputs:
2 channels for veto scintillators
4 channels for analog signals from AHCAL
TLU settings (threshold, delay, veto stretch) can be adjusted via software.
No firmware update required.
Configuration validated during previous test beam campaigns.
Simulation tested conditions for neutron rejection and ν_eCC efficiency.
Trigger condition:
At least 2 of layers 18, 19, 38, or 39 receive signal > 0.2 MeV within 10 ns window.
Efficiency:
ν_eCC detection: ~98%
Good suppression of delayed neutron background.
Need to confirm where the sensitive region of AHCAL begins relative to the floor.
This affects placement height of veto scintillators.
Yunlong/Zhen to confirm sensitive region height with photos and measurements.
Brian to propose scintillator dimensions (suggested: 80x80 cm).
Implemented new digitization from Hongbin:
Cell-by-cell calibration of SiPM and electronics characteristics.
Consideration of low-gain saturation effects.
Artificial cap at 80 MeV per cell introduced for worst-case scenario.
ν_eCC Energy reconstruction:
Std. Dev. (E_reco/E_truth):
Old: 29%
Updated: 32%
With saturation: 35%
ν_eCC PID and background rejection:
Slight improvement with calibrated digitization.
Slight degradation with saturation, but within acceptable bounds.
Digitization changes do not significantly impact overall detector performance.
GEANT4 does not fully simulate decay of charm hadrons and tau leptons.
Previously defaulted to hadronic decay only.
Introduced Pythia8 decay handling.
Enabled more realistic decay chains including leptonic channels.
ν_eCC PID rejection performance:
Slight drop (~8%) in ν_μCC and NC rejection due to muon tracks.
Minor effect on ν_eCC detection.
Flux measurement uncertainty:
Increased slightly (from 56%~112% to 57%~118%).
No critical degradation.
Handling of D decays via Pythia8 is preferred for realism.
Shunliang will visit the site and take photographs.
Frame geometry, lifting hook placements, and sensitive region locations will be documented.
Scintillator placement depends on active volume height.
Placement should avoid interference and align with active area.
Frame transportation challenge actively discussed.
DAQ and digitization components are mostly ready.
Trigger logic and placement design progressing.
Next Meeting Tasks:
Share frame photos and detailed geometry.
Finalize cradle/lifting structure design.
Confirm trigger logic parameters with hardware.
Validate decay model impact with further simulation if needed.
