Particle Physics Flashcards
How is specific charge calculated?
the overall charge of the atom/nucleus divided by the total mass of the atom/nucleus
(total protons x charge of a proton) / (total nucleons x mass of a nucleon)
NpQp/NnMn
What is the charge of a proton?
1.6x10^-19C
What is the charge of a neutron?
0C
What is the charge of an electron?
-1.6x10^-19
What is meant by the ‘rest mass’ of a particle?
the minimum mass of a particle is when it is at rest, hence this is the ‘rest mass’
What is the mass of a proton?
1.67x10-27kg
What is the mass of a neutron?
1.67x10-27kg
What is the mass of an electron?
9.11x10-31kg
Define nucleon number, and state which letter this is represented by.
the total number of protons and neutrons within the nucleus, A
Define proton number, and state which letter this is represented by.
the total number of protons in the nucleus or the total number of electrons orbiting the nucleus, Z
What is an Isotope?
an atom which contains the same number of protons and electrons as its element but has a different number of neutrons
What force holds together the nucleus of an atom and what is its attractive range?
Strong nuclear force, 3fm
What is the repulsive range of the strong nuclear force and why is this useful?
0.5fm, it prevents the nucleus from collapsing in on itself
What subatomic particles make up an alpha particle and state the charge of this particle?
2 protons and 2 neutrons (Helium nucleus), 2+ charge
What is the range of alpha radiation in air and what barrier can be used to stop it?
approx. 5cm, thin paper
When might a nucleus undergo alpha decay?
when its mass number is very large
Which particles are emitted during beta minus decay?
a fast moving electron and an antineutrino
What happens during beta minus decay?
a neutron turns into a proton and an electron and antineutrino are emitted.
Why do nuclei undergo beta minus decay?
the nucleus has too many neutrons
What is emitted during gamma decay?
a gamma photon
What happens during gamma decay?
EM radiation is emitted from the unstable nucleus in the form of a photon.
When do nuclei experience gamma decay?
when they have too much energy
What is a neutrino and why is it released during beta decay?
it was hypothesised this was to balance the conservation of energy. it also balances lepton number.
What is an antiparticle?
every particle has a corresponding antiparticle. It has the same mass and rest energy but an equal and opposite charge. it is made of antiquarks.
Which particles are released during beta plus decay?
positron and neutrino
What happens during beta plus decay?
a proton turns into a neutron and a positron and neutrino are released.
Why do nuclei experience beta plus decay?
if a nucleus is proton rich
What is the antiparticle of an electron?
positron
What is the antiparticle of a proton?
antiproton
What is the antiparticle of a neutron?
antineutron
What is annihilation?
when a particle and its antiparticle meet they are destroyed releasing a large amount of energy via photons. the amount of energy released is the rest energy of the particle/antiparticles.