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Collision of particles in physics labs
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Particle physicists use conserved energy and momentum to find unknown masses.
Detectors reconstruct particle masses from conserved energy and momentum. Invariant mass M² = (ΣE)² − |Σp|² (c = 1) identifies decay products.
The Higgs boson shows as a peak in the invariant mass of photon pairs near 125 GeV.
Missing momentum signals an undetected particle such as a neutrino.
In more detail
Particle collisions in labs are studied by measuring the momenta and energies of the products. Conservation laws let researchers identify particles and their masses.
Real-world uses
- Particle detectors identify particles by tracking their momenta.
- Students study collisions with air-track gliders to test momentum conservation.
- Particle physics experiments use energy and momentum conservation to deduce the mass of an unseen particle from its decay products.
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Frequently asked questions
How do scientists measure momentum?
By tracking the curvature of paths in magnetic fields, which gives momentum.
Are high-energy collisions different?
They can create new particles, but momentum and energy are still conserved.
How can an unseen particle be detected?
By measuring the energies and momenta of its decay products and checking which mass makes the totals consistent.
Related topics in Momentum & Collisions
Conservation of angular momentum · Ice-skater spin · Kepler's second law from L · Compton scattering · Newton's cradle · Momentum of light