The structure of matter

Nature of science:

Predictions: Our present understanding of matter is called the Standard Model, consisting of six quarks and six leptons. Quarks were postulated on a completely mathematical basis in order to explain patterns in properties of particles. (1.9) Collaboration: It was much later that large-scale collaborative experimentation led to the discovery of the predicted fundamental particles. (4.3)

• Quarks, leptons and their antiparticles
• Hadrons, baryons and mesons
• The conservation laws of charge, baryon number, lepton number and strangeness
• The nature and range of the strong nuclear force, weak nuclear force and electromagnetic force
• Exchange particles
• Feynman diagrams
• Confinement
• The Higgs boson

Applications and skills:

• Describing the Rutherford-Geiger-Marsden experiment that led to the discovery of the nucleus
• Applying conservation laws in particle reactions
• Describing protons and neutrons in terms of quarks
• Comparing the interaction strengths of the fundamental forces, including gravity
• Describing the mediation of the fundamental forces through exchange particles
• Sketching and interpreting simple Feynman diagrams
• Describing why free quarks are not observed

• Research into particle physics requires ever-increasing funding, leading to debates in governments and international research organizations on the fair allocation of precious financial resources

Theory of knowledge:

• Does the belief in the existence of fundamental particles mean that it is justifiable to see physics as being more important than other areas of knowledge?

Utilization:

• An understanding of particle physics is needed to determine the final fate of the universe (see Physics option sub-topics D.3 and D.4

Aims:

• Aim 1: the research that deals with the fundamental structure of matter is international in nature and is a challenging and stimulating adventure for those who take part
• Aim 4: particle physics involves the analysis and evaluation of very large amounts of data
• Aim 6: students could investigate the scattering angle of alpha particles as a function of the aiming error, or the minimum distance of approach as a function of the initial kinetic energy of the alpha particle
• Aim 8: scientific and government organizations are asked if the funding for particle physics research could be spent on other research or social needs

• A qualitative description of the standard model is required

Data booklet reference: