1.5 Particle interactons Flashcards
How can force be measured?
» Using newton meters and force sensors
What is the equation for momentum?
» mass x velocity
What happens when 2 objects interact?
» They exert equal and opposite forces on each other
» Momentum is transferred between the objects by these forces
What is the electromagnetic force between 2 charged objects due to?
» Virtual protons, such as the interaction between 2 protons
Why can’t we detect virtual protons?
» If we detect them by using a detector we would stop the force acting on the charged particles
» Describe the Feynman diagram between 2 protons
» 2 protons straight line towards the exchange particle
» Exchange particle is the virtual photon
» Resultant particles are 2 protons
What does the strong nuclear force do?
» Overcomes the electrostatic forces of attraction and holds the neutrons and protons in a nucleus together
Why can’t beta decay be caused by the strong nuclear force?
» Cannot be caused by electromagnetic forces as the neutron is uncharged
What can we conclude if the strong nuclear force is not responsible for beta decay?
» Must be weaker than the strong nuclear force, otherwise it would affect the stable nuclei
» What is the force called which causes beta decay?
» Weak nuclear force
What particles are produced when a neutrino interacts with a neutron?
» Proton and an electron
What exchange particle is present when a neutrino interacts with a neutron?
» W ^ - boson
How can you figure out what exchange particles is needed for the interaction?
» Draw 2 lines at each vertex, then calculate using the overall charge before, and the overall charge after
What particles are produced when a proton interacts with an antineutrino?
» Neutron and a beta plus particle
What exchange particle is responsible for the interaction between the antineutrino and the proton?
» W+ Boson
What are the W boson particles responsible for?
» Responsible for the rare interactions and exchange of these particles
What are some common facts about W bosons?
» Have a non-zero rest mass
» Have a very short range
» Can be both negatively and positively charged
What is the range of a W boson particle?
» 0.001 fm
What is the lifetime of a w boson particle?
» x 10 ^ -27 seconds
What is the role of the boson in beta decay?
» If it meets a neutrino or antineutrino, it changes them into an electron or a positron respectively
» What is the role of W boson particle if no neutrino or antineutrino is present?
» W - boson decays into a B- particle and an antineutrino
» W+ boson decays into a B+ particle and a neutrino
What is the equation for B- decay?
n » p + B- + antineutrino
What exchange particle is present in beta - decay?
» W- boson particle
What is the equation for B+ decay?
p » n + positron + neutrino
