Chapter 1: Particle Physics Flashcards
What particles can interact via the weak force?
all hadrons (all quarks) and all leptons too
Which particles can interact with the strong force?
all quarks (all hadrons) only hadrons experience the strong force
What particles interact with the electromagnetic force?
all charged particles
How are forces exerted between objects?
forces between objects are exerted by the exchange of virtual particles and bosons (exchange particles)
What is particle decay?
If no work is done into a system, what will the particles tend to do?
when exotic, heavier particles change to smaller more stable particles
if no work is done into a system, the particles will tend back to more stable particles
What must always be assumed is conserved in particle interactions?
energy/mass
momentum
What must be proven to be conserved in particle interactions in an exam?
charge
baryon number
lepton number
How fast is the decay via strong force?
fast decay via the strong force
How fast is the decay via the weak force?
slow decay via the weak force
How must strange particles be produced?
strange particles must be produced in pairs
How are strange particles produced?
via the strong force
When is strangeness conserved and when is it not conserved?
strangeness must be conserved in decays via the STRONG force
strangeness doesn’t have to be conserved in weak interactions- can change by +1, -1 or it can be conserved (0)
What is an example of a strange particle and why is it strange?
Kaon
they are big particles but take a long to time to decay compared to their mass and they do not conserve strangeness so it can only decay via the weak interaction
How do strange particles decay?
via the weak interaction
Why is strangeness not conserved in weak interactions?
because weak forces cause quarks to change type so it can cause strange quarks to change into a different type of quark ∴ strangeness is not conserved
What causes particles to be strange?
a strange quark causes all this strange behaviour
What are the 6 main properties of particles?
energy-mass charge spin strangeness lepton number baryon number
What is one MeV in joules?
1 MeV = 1.60 x 10⁻¹³J
What is one atomic mass unit?
it is approximately the mass of one nucleon (either a single proton/neutron)
What is specific charge and its units?
it is the charge to mass ratio
specific charge= Ckg⁻¹
it influences particle behaviour
What is dependent on the value of specific charge?
specific charge influences how much a particle is deflected when it is in an electric/magnetic field
greater specific charge—- more the particle is deflected
smaller specific charge—- less the particle is deflected
no specific charge —- no deflection
What is the specific charge of an Mg 2+ ion?
2 * 1.60 *10 ⁻¹⁹ charge
24 * 1.67 * 10⁻²⁷ mass
charge/mass == 7.98 *10⁶ Ckg⁻¹
How does the specific charge of an ion compare to the specific charge of a particle?
specific charge of an ion is much smaller than that of a particle
this is because neutrons are in ions which add to the mass but not the charge
