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Higgs Observatory

CMS / collision · detection · evidence

01 / Detector view

Maintenance opening

The endcaps separate for inspection; the event display is suspended until the apparatus is reclosed. Replay recloses it.

Sensor hitsLabelsField linesContext tracks

Apparatus layers

visibility

Silicon tracker

ECAL · crystals

HCAL · brass / scintillator

Solenoid / cryostat

Steel return yoke

Muon chambers

Cables & cooling

Hiding a layer only changes the view. Readout switches change the measurement.

02 / Collision lesson

Seed

Higgs transverse momentum

A recoil parton balances transverse momentum. Remnants and hadronization are not simulated.

Stages are recomputed from the seed; stepping back is not a physical reversal. Use the Run, Pause and Replay transport to play the replay.

03 / Test the measurement

Solenoid field

Tracker readout

ECAL readout

Muon readout

Response smearing

Switch a readout off and replay: particles still interact with material, but that measurement is lost.

Changing the channel, field, response, readout, Higgs pT or signal fraction cancels a running batch and clears incompatible histogram records.

Record

Restores the source defaults for controls and view. Histogram records are kept only if the measurement profile is unchanged; the candidate log is kept.

Drag to orbit · scroll / pinch to zoom
Shift-drag / right-drag to pan
Spaceplay/pause ·Nnext event
1Cutaway ·2Exterior · 3X-ray

LHC · Point 5 · CMS-inspired · discovery-era layout, about 21 m × 15 m

The invisible, reconstructed.

pp · √s = 8 TeV

muonelectronphoton direction

Select the scene to use wheel zoom and keyboard shortcuts

Building the CMS laboratory

Detector geometry · event generator · reconstruction · all local

Reconstruct the parent

—GeV/c²

Sum of reconstructed daughter four-vectors, not an assigned Higgs label.

Your laboratory

Current event mass: — GeV/c²
Trials in histogram: 0

Detected objects

select to inspect

Sensor hits
Objects
Mass

Generator truth & conservation audit

Executable consistency checks

From events to evidence

One peak. Many collisions.

Collect a synthetic, signal-enriched sample. A resonance appears as an excess over a smooth continuum, not as a special-looking individual event.

■ Candidate counts— Fitted total┄ Continuum

In mass window0

Toy local Z—

No sample collected yet. Window: 100–160 GeV/c².

This is not CMS data, luminosity, or discovery significance. The likelihood uses fixed toy shapes; detector systematics and the look-elsewhere effect are omitted.

Generated signal fraction

0% gives background only. This is an artificial mixture, not a Higgs production or decay probability.

The same hit/energy reconstruction and object cuts are applied to every trial.

How the toy statistical test works

Fit nonnegative signal and background yields to the binned Poisson likelihood. The null is an exponential continuum; the alternative adds a Gaussian at 125 GeV. Z = √[2 ln(L(S+B) / L(B))] is an asymptotic, fixed-mass local approximation. The continuum template includes an independently generated selection-acceptance correction. This is a teaching exercise, not a discovery claim.

Candidate log

Each row is one seeded event with its own configuration. Rows are individual candidates, not combined statistics.

Event	Channel	Mass (GeV/c²)	Selection	Field / readouts

No candidates recorded.

.museum-body--immersive { overflow: auto !important; } .museum-main--fill, .museum-runtime { height: auto !important; min-height: 100vh; overflow: visible !important; } .museum-runtime > .exhibit-root, .museum-runtime > :not(#mw-about):not(noscript):not(script) { display: none !important; } .museum-runtime #mw-about { display: block !important; position: static; width: min(100%, 800px); margin: 24px auto; padding: 24px; box-sizing: border-box; } .museum-runtime [data-about-close], .museum-runtime #mw-about > h2 { display: none !important; }

2012 · Physics

Higgs Boson Detector

Follow one simulated collision from sensor hits to a reconstructed mass, then collect thousands to see why one candidate is never a discovery.

No detector ever sees a Higgs boson. It decays about 10⁻²² seconds after it is made, so physicists reconstruct it from what its daughters leave behind: charge collected on silicon pixels, light in calorimeter crystals, and timed pulses in the muon chambers. This laboratory follows one seeded, synthetic collision through a CMS-inspired, discovery-era detector — beams, a prompt decay, sensor hits, digitized readout — and sums the measured four-vectors into one invariant mass.

The physics is simplified but causal. Tracks bend in an approximate 3.8 T solenoid field integrated with fourth-order Runge–Kutta; a circle fit to noisy hits recovers momentum and charge; calorimeter energy is smeared and digitized. Switch off a readout or the magnetic field and the particles still cross the same material, but the measurement is lost, and the model refuses to quote a mass. Magnified sensor labs show how silicon, lead-tungstate crystals, drift cells and brass–scintillator sampling turn a particle into a signal.

A single Higgs-compatible candidate is not a discovery: background processes produce the same final states. The Evidence panel collects batches of 1,000 synthetic trials with the same reconstruction and cuts, fits a continuum plus a fixed-mass signal template, and reports a toy local significance. Changing the measurement configuration clears incompatible samples rather than mixing them. It is a teaching model — not CMS data, not a validated detector simulation, and not affiliated with or endorsed by CERN or CMS.

Specifications

Collision energy: √s = 8 TeV (2012 discovery era)
Solenoid field: 3.8 T nominal, approximate field map
Decay channels: H → γγ, H → ZZ* → 2e2μ and 4μ
Pixel layer radii: 4.4, 7.3 and 10.2 cm
Detector size: About 21 m long, 15 m in diameter
Evidence batch: 1,000 synthetic trials per batch
Data: Synthetic educational events, not CMS data

All exhibits

The invisible, reconstructed.

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