Particles and nuclear structure Flashcards
Describe quarks
Relatively high mass, either ‘up’ or ‘down’ type, affected by strong force.
Describe leptons
Lightweight particles, two types- electron and electron neutrino, affected by weak forces.
What are the characteristics of an antiparticle?
They have the same mass but opposite charge, lepton number and baryon number.
What happens when a particle and its corresponding antiparticle collide?
Annihilation occurs. They cease to be and their mass is converted into a pair of photons.
What is charge (e)?
The magnitude of the charge of a proton.
What is the charge of an up quark?
+2/3.
What is the charge of a down quark?
-1/3.
What are hadrons?
Composite particles made of quarks.
What are the three types of hadron?
Baryon (combination of three quarks)
Antibaryon (combination of three antiquarks)
Meson (quark and antiquark pair)
What is the quark composition of a proton?
uud
Charge: +1
What is the quark composition of a neutron?
udd
Charge: 0
What is the quark composition of a delta plus plus baryon?
uuu
Charge: +2
What is the quark composition of a delta minus baryon?
ddd,
Charge: -1
What is the quark compostions of a pi plus meson?
uḋ
Charge: +1
What is the quark composition of a pi minus meson?
ūd
Charge: -1
What is the quark composition of a pi zero meson?
uū or dḋ
Charge: 0
What is the charge and lepton number of an electron?
Charge: -1
Lepton number: +1
What is the charge and lepton number of an electron neutrino?
Charge: 0
Lepton number: +1
What is the conservation of momentum?
In any interaction between particles in a system, the total momentum must stay constant.
What is the conservation of mass-energy?
In any interaction between particles in a system, mass energy should neither be created or destroyed.
What is the conservation of charge?
In any interaction between particles in a system, the total charge in the system must not change.
What is the conservation of baryon number?
In any interaction between particles in a system, the total baryon number in the system must not change.
What is the conservation of lepton number?
In any interaction between particles in a system, the total lepton number of the system must not change.
Describe gravitational force
Experienced by: all particles
Range: infinite
• Not applicable to the interactions of sub-atomic particles
Describe weak force
Experienced by: all particles
Range: very short
• Neutrino or antineutrino involved • Change of quark flavour • Long time (10^-12s)
Describe electromagnetic force
Experienced by: charged particles
Range: infinite
• Photons involved • Particles interacting have charge • Typical time is 10^-17s
Describe strong force
Experienced by: quarks
Range: short
• Only hadrons involved • No change of quark flavour • Takes very little time(10^-23s)
