AQA ยท A level Physics

Doubly charmed baryon A-level Physics challenge

Can you get 100%? Use CERN's new doubly charmed baryon to test quark charge, baryon number and how decay products reveal a short-lived particle.

Read about CERN's doubly charmed particle

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Question

8 marks

Answer all parts. Show your working and give units where appropriate.

1(a)

The new baryon has quark composition ccs. A charm quark has charge +2/3 e and a strange quark has charge -1/3 e. Each quark has baryon number +1/3. Determine the particle's electric charge and baryon number.

[3 marks]

1(b)

The baryon decays before reaching the detector. The detector measures the momenta and energies of its charged decay products. Explain how many recorded collisions can reveal the mass of the parent particle.

[3 marks]

1(c)

State two checks needed before the mass peak is accepted as a new particle rather than a statistical fluctuation or detector error.

[2 marks]

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