3D Radiation Decay Event Simulator

Detector Setup

True background rate 30 cpm

Counting window 10 s

Anomaly threshold 3σ

Live Readout

Verdict

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Count this window

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Expected (λ)

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σ = √λ

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z-score

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Windows seen

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False "spikes"

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Each glowing pip is one simulated decay event popping in around the detector at a random moment — the pip cluster's size fluctuates window to window even though the true rate never changes.

How it works

Each decay event here is an independent, memoryless random arrival — the defining property of a Poisson process. The 3D scene renders every event as an individual particle popping into existence at a random position around the detector core the instant it "fires," then fading out. Counting how many pips appear in a fixed window gives a count whose mean is λ = rate × window and whose standard deviation is fixed by the physics at σ = √λ — never a free choice, and never zero.

λ = rate × window
σ = √λ
z = (observed − λ) / σ
flag "anomaly" only if |z| ≥ threshold

True background rate — the detector core's real, constant decay rate. It never changes in this simulation, yet the pip count per window still swings widely — that swing is the point.
Counting window — longer windows accumulate more events (bigger λ), and because σ/λ shrinks as window length grows, a genuinely elevated rate becomes distinguishable from noise only with enough counting time.
Anomaly threshold — the ring around the detector flashes red only when a window's z-score crosses this many σ. Watch how often it flashes red purely from chance at a low threshold, even with a perfectly steady source.

Real-world relevance: a single brief Geiger reading at a sighting site that reads "double" or "triple" background is exactly what an unchanged Poisson source does routinely — the 3D pip cloud makes visible that a "spike" is just a locally dense cluster of independent, ordinary random arrivals, not evidence of an exotic emission.

Decay event pip Detector core Window flagged (noise)

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