EM Calorimeter Shower (Heitler / Rossi)

This interactive simulator explores EM Calorimeter Shower (Heitler / Rossi) in Astronomy & The Sky. Toy electromagnetic cascade in a calorimeter: γ → e⁺e⁻, e⁻ → e⁻γ each X₀, with critical-energy cutoff E_c. Animate the branching tree, see N_max ≈ E₀/E_c, t_max ≈ log₂(E₀/E_c) live; presets for Pb, Cu, Si, air. Use the controls to change the scenario; watch the visualization and any graphs or readouts to connect the model with lectures, labs, and homework.

Who it's for: For learners comfortable with heavier math or second-level detail. Typical context: Astronomy & The Sky.

Key terms

calorimeter
shower
heitler
rossi
em shower heitler
astronomy

How it works

Heitler–Rossi electromagnetic shower — a toy model of how a high-energy γ or electron deposits energy in a calorimeter. Every radiation length X₀, an electron emits a bremsstrahlung γ and every γ pair-produces an e⁺e⁻ with the energy split 50:50, until each daughter falls below the critical energy E_c, at which point ionisation losses dominate and the cascade dies. The number of particles roughly doubles each X₀, giving the classic N_max ≈ E₀/E_c at depth t_max ≈ log₂(E₀/E_c) — the basis of all sampling-calorimeter design (LHC, CMS ECAL, ATLAS LAr). Animate the cascade growing into a lead absorber.

Key equations

e⁻ → e⁻ + γ (each X₀) γ → e⁺ e⁻ (each X₀)

N(t) ≈ 2ᵗ, ⟨E⟩(t) ≈ E₀ / 2ᵗ, stops when ⟨E⟩ = E_c

N_max ≈ E₀ / E_c, t_max ≈ log₂ (E₀ / E_c)

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EM Calorimeter Shower (Heitler / Rossi)

How it works

Key equations

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Venus Phases (Galileo)

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Milankovitch Cycles

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Apparent vs Absolute Magnitude

EM Calorimeter Shower (Heitler / Rossi)

How it works

Key equations