Classification of particles: hadrons and leptons

Complete the particle equation for this decay.

Explain whether the conservation laws of charge and baryon number are obeyed for this decay.

The table summarises the charges for three types of quark.

The sigma particle has one strange quark within its structure.

State why the neutron does not leave a track.

The initial momentum of the positive pion is 1.1 10^–19N s. The scale of the diagram is 1 cm represents 15 cm.

Determine the magnitude of the magnetic flux density acting perpendicularly to the tracks.

The decay of a positive muon produced a positron, an electron neutrino and a muon antineutrino. The diagram shows the tracks formed in a particle detector.

A muon belongs to a family of particles called leptons.

State two features that all particles in the lepton family have in common.

Write a nuclear equation for the decay of the muon (μ) described above.

Describe the role of the magnetic field in a particle detector.

Explain how the diagram gives evidence that a particle or particles, other than the positron, were produced in this decay.

The π⁻ particle has a mass of 140 MeV / c².

Which row of the table is correct for the antiparticle of a π⁻?

A negatively charged pion decays into a muon and an antineutrino. The diagram shows tracks in a particle detector formed in such an event.

Deduce whether the antineutrino is charged, giving two reasons for your decision.

Write a particle equation to represent this decay.

According to the standard model, the pion and muon are classified within two different groups of particles.

State which group each particle belongs to and describe the two groups.

The momentum of the pion just before it decays is 9.1 × 10⁻²⁰N s.

Determine the magnetic flux density of the magnetic field which acts in the detector and state its direction.

Scale of diagram 1 cm represents 10 cm

Use a vector diagram to determine the momentum of the antineutrino.

The initial momentum of the muon is 1.59 × 10⁻¹⁹N s.

A negatively charged pion decays into a muon and an antineutrino. The diagram shows tracks in a particle detector formed in such an event.

Deduce whether the antineutrino is charged, giving two reasons for your decision.

Write a particle equation to represent this decay.

According to the standard model, the pion and muon are classified within two different groups of particles.

State which group each particle belongs to and describe the two groups.

The momentum of the pion just before it decays is 9.1 × 10⁻²⁰N s.

Determine the magnetic flux density of the magnetic field which acts in the detector and state its direction.

Scale of diagram 1 cm represents 10 cm

Use a vector diagram to determine the momentum of the antineutrino.

The initial momentum of the muon is 1.59 × 10⁻¹⁹N s.

The discovery of the Higgs particle was an important contribution to our understanding of particle physics.

Describe the standard model for subatomic particles. You should identify the fundamental particles and the composition of the particles we can observe.

The mass of the Higgs particle is 2.2 10^–25 kg.

Calculate this mass in GeV/c².

The Higgs particle was discovered using the Large Hadron Collider (LHC) in 2012. Two beams of very high energy protons, moving in opposite directions, were made to collide.

Explain the need for such high energy collisions.

The beams of protons are contained within a ring of superconducting magnets.

Calculate the momentum of a proton in a beam.

magnetic field strength = 8.3 T circumference of the ring = 27 km

State the total momentum of the products of the collision between the two beams of protons.

The LHC accelerates protons until they gain energies of about 7 TeV.

A student used the equation E = to predict the energy of a proton in the beam, using the momentum calculated in (c)(ii), but found the energy was far higher than 7 TeV.

Explain why.

The neutral lambda Λ⁰ particle is a baryon of mass 1116 MeV/c² and contains one strange quark.

The table shows quarks and their relative charge.

State, with justification, the quark content of a Λ⁰ particle.

Calculate the mass of the Λ⁰ particle in kg.

A student suggests five ways a Λ⁰ particle might decay. These are

Deduce which of these decay processes are not possible.

Lambda particles were first detected in experiments which made use of cosmic rays entering the atmosphere. Cosmic rays are mainly high‑energy protons which have a mass less than that of a lambda particle.

Explain why a cosmic ray could lead to the creation of a lambda particle.

The Λ⁰ particle cannot be directly observed in particle experiments, however some of the decay products can.

Explain why the Λ⁰ particle cannot be directly observed but information about it can be obtained by studying its decay particles.