LHC Run 3 · proton–proton · √s = 13.6 TeV

ATLASlayer by layer

Two bunches of protons cross at the centre of a 25-metre detector. Whatever comes out leaves hits in every layer it passes through. Scroll to take the detector apart, from the outside in.

Back together

Every layer you just took apart does this for 40 million bunch crossings a second.

t: 0.0 ns
scale: 10 m

How this is drawn

The detector is drawn to scale from published ATLAS dimensions: barrel radii and lengths, module counts and layer positions. As the layers come off, the camera zooms from 25 metres down to a few millimetres instead of squeezing the radius.

The collisions are toy simulations made for illustration, not ATLAS data. Each replay draws a new process with proper decay kinematics, about 60 pile-up collisions in the same crossing (thinned to tracks above 0.4 GeV), a 2 T solenoid curving every charged track, and hits and calorimeter deposits where those particles would leave them.

tracker, solenoid
LAr calorimeter
Tile calorimeter
muon chambers
toroid coils
charged tracks
electrons
photons
muons
missing E_T

Motion by anime.js 4.5 (MIT). Drawn on a 2D canvas, no WebGL.

The layers, outside in
Layer	Radius	Half-length	What it is
Muon spectrometer	4.5–12 m	22 m	Drift tubes (MDT) for precision, RPC and TGC chambers for the trigger, New Small Wheels since Run 3
Toroid magnets	4.9–10.1 m	12.65 m	8 air-core superconducting barrel coils plus two endcap toroids, about 0.5–1 T
Tile calorimeter	2.28–4.25 m	6.1 m	Steel and scintillating tiles, 64 modules around the beam
LAr calorimeter	1.40–1.97 m	3.2 m	Lead and liquid argon in an accordion, over 22 radiation lengths
Solenoid	1.23–1.28 m	2.9 m	2 T along the beam, about 0.66 radiation lengths thick
TRT	0.55–1.08 m	0.71 m	About 300,000 straw tubes, 4 mm across
SCT	0.30–0.51 m	0.75 m	Silicon strips, 4 barrel layers and 9 discs per side
Pixels + IBL	33–123 mm	0.40 m	Silicon pixels, about 92 million channels
Beam pipe	23.5 mm	—	Beryllium, around the interaction point