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Date May 2011 Marks available 1 Reference code 11M.3.SL.TZ1.12
Level Standard level Paper Paper 3 Time zone Time zone 1
Command term State Question number 12 Adapted from N/A

Question

This question is about mesons.

State what is meant by an exchange particle.

[1]
a.

A meson called the pion was detected in cosmic ray reactions in 1947 by Powell and Occhialini. The pion comes in three possible charge states: π+ ,π and π0. The Feynman diagram below represents a possible reaction in which a pion participates.

State and explain whether the meson produced is a π+ ,π or  a π0.

 

[2]
c.

Markscheme

a particle that mediates/carries/transmits one of the fundamental forces / a particle that is exchanged between two particles when undergoing one of the fundamental interactions / OWTTE;

a.

π+;
from conservation of charge at either vertex, the pion must have charge of +1;

c.

Examiners report

[N/A]
a.
[N/A]
c.

Syllabus sections

Core » Topic 7: Atomic, nuclear and particle physics » 7.3 – The structure of matter
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