CERN T9 Proposal Visualizer

Invariant Mass Reconstruction: m_π⁰ = √(2E₁E₂(1 - cos θ)) ≈ 135 MeV/c².

The Dalitz Catch: 1.2% of neutral pions undergo Dalitz decay (π⁰ → γe⁺e⁻). We use veto scintillators to reject this irreducible background.

Electromagnetic Shower (Pair production & Bremsstrahlung).

Target Material: Lead (Pb). Radiation Length X₀ = 0.56 cm. Stops photons rapidly.

Cherenkov PID: Gas pressure tuned so electrons emit light, pions do not.

Threshold Kinematics: Based on velocity (β = p/E) at 3 GeV/c, the electron is strictly above the emission threshold (β_e ≈ 1 > 1/n), while the pion remains completely dark (β_π < 1/n).

Delay Wire Chambers (DWC) for Beam Tracking

Function: DWCs provide an X-Y coordinate grid of the beam profile before it hits the target, ensuring proper alignment. Click to simulate a beam hit.

Complete T9 Beamline Setup with Photon Conversion

Beam → Magnet → C1 → C2 → S1 → D1 → D2 → Target → S2 (Veto) → Pb Conv → DWC3 → Calorimeter

Center-of-Gravity Position Reconstruction Algorithm

Math: x = Σ(E_i · x_i) / Σ E_i. Click the calorimeter face to simulate a photon hit.