Problem
Phoenix has a great 3D event display but no 2D projection view. When students try to identify particles in masterclasses, overlapping objects in 3D make it hard to tell isolated electrons from jet-associated tracks. Physicists use eta-phi lego plots for exactly this reason (its on basically every ATLAS/CMS talk slide), but no web-based event display has an interactive one. ROOT EVE has it but that needs a full ROOT server setup.
Proposal
Add a new overlay panel that shows all physics objects plotted on an eta-phi grid:
- Calorimeter energy (CaloCells/CaloClusters) as colored towers binned into an eta-phi grid
- Reconstructed objects (jets, electrons, muons, photons) as markers/icons overlaid on the grid
- MET as a directional arrow showing the missing transverse energy direction
- Color scale for energy magnitude
The key feature is bidirectional linking with the 3D view:
- Click a tower/marker in the energy map -> highlights the corresponding object in 3D
- Click an object in 3D -> highlights the corresponding bin in the energy map
- Hover preview in both directions
In the eta-phi view, particle identification becomes visual pattern matching:
- Isolated electron = single energy tower far from any jet cluster
- Jet = cluster of adjacent towers
- Z->ee event = two isolated towers on opposite sides
- MET = arrow pointing away from the energetic side
Students can see the event structure at a glance in a way that's really hard to get from the 3D view alone. The two views together give a much more complete picture.
Implementation notes
- All the data is already there (CaloCells, Jets, Tracks, Electrons etc. all have eta/phi fields)
- Coordinate helpers (etaToTheta, etaPhiToCartesian) already exist in the codebase
- Can use Canvas 2D for rendering (no new dependencies needed)
- Same CDK overlay panel pattern as the event browser and kinematics panel
- Experiment-agnostic by design (just configure eta range per experiment, e.g. LHCb uses 2-5 instead of -5 to 5)
- Selection API already supports programmatic highlighting by UUID so the bidirectional linking should work with existing infrastructure
Problem
Phoenix has a great 3D event display but no 2D projection view. When students try to identify particles in masterclasses, overlapping objects in 3D make it hard to tell isolated electrons from jet-associated tracks. Physicists use eta-phi lego plots for exactly this reason (its on basically every ATLAS/CMS talk slide), but no web-based event display has an interactive one. ROOT EVE has it but that needs a full ROOT server setup.
Proposal
Add a new overlay panel that shows all physics objects plotted on an eta-phi grid:
The key feature is bidirectional linking with the 3D view:
In the eta-phi view, particle identification becomes visual pattern matching:
Students can see the event structure at a glance in a way that's really hard to get from the 3D view alone. The two views together give a much more complete picture.
Implementation notes