3.2 Particles and radiation Flashcards
What is a nucleon?
A proton or neutron
What is the nucleon number?
The number of protons and neutrons in an atom (atomic mass)
What is a nuclide?
A particular nucleus
What is an isotope?
An atom with the same number of protons but a different number of neutrons
What is the process in which isotopes can be used to find the approximate age of an object containing organic material?
Carbon dating
What is the role of the strong nuclear force?
To keep the nucleus stable
What particles can feel the strong nuclear force?
Hadrons
What is the range of the strong nuclear force?
0.5 - 3 fm (x10^-15 m)
Repels hadrons <0.5 fm
Attraction up to 3 fm
What is the specific charge of a particle?
The charge-mass ratio
Why are some nuclei unstable?
They have too many protons, neutrons or both
What is the word equation for β- decay?
Neutron -> proton + electron + anti-electron neutrino
What is the symbol equation for β- decay?
n -> p + e- + (bar) Ve
What is the quark equation for β- decay?
udd -> uud
d -> u
What is the word equation for β+ decay?
Proton -> neutron + positron + electron neutrino
What is the symbol equation for β+ decay?
p -> n + e+ + Ve
What is the quark equation for β+ decay?
uud -> udd
u -> d
What is the only difference between between a particle and its corresponding anti-particle?
They are oppositely charged (baryon and lepton number also different) (mass and rest energy is the same)
What is the anti-particle of an electron?
Positron
What is annihilation?
- When a particle and its corresponding anti-particle collide, resulting in their masses being converted into energy
- This energy, along with the kinetic energy of the two particles, is released in the form of 2 identical gamma photons moving in opposite directions in order to conserve momentum
What is pair production?
Where a photon is converted into an equal amount of matter and antimatter
When can pair production occur?
When a photon has an energy greater than the total rest energy of both particles, as any excess energy is converted into kinetic energy of the particles
What are the 4 fundamental forces?
Gravity, electromagnetic, strong nuclear force and weak nuclear force
What is the exchange particle in a weak interaction?
W boson (W+ or W-)
What is the range of the weak nuclear force?
10^-18 m
What does the weak nuclear force act on?
All particles
What is the exchange particle in an electromagnetic interaction?
Virtual photon (Y)
What is the range of an electromagnetic interaction?
Infinite
What does an electromagnetic interaction act on?
Charged particles
What is the range of gravity?
Infinite
What does gravity act on?
Particles with mass
What are the two classes of hadrons?
Baryons (protons, neutrons) (and antibaryons (antiprotons and antineutrons) and mesons (pions, kaons)
What is the baryon number of a baryon?
1
What is the charge of the up (u) quark?
+2/3 e
What is the charge of the down (d) quark?
-1/3 e
What is the charge of the strange (s) quark?
-1/3 e
What is the baryon number of the up (u) quark?
1/3
What is the baryon number of the down (d) quark?
1/3
What is the baryon number of the strange (s) quark?
1/3
What is the strangeness of the strange (s) quark?
-1
What is the quark composition of a baryon?
3 quarks
What is the quark composition of a meson?
A quark and an antiquark (baryon number of 0)
What is the quark composition of an anti-baryon?
3 anti quarks
Is the baryon number always conserved in particle interactions?
Yes
Is the lepton number always conserved in particle interactions?
Yes
What is the only stable baryon?
Proton
What is the exchange particle of the strong nuclear force?
Pion
What is the particle that can decay into pions?
Kaons
What particle decays into an electron?
Muon
How are strange particles produced?
Through the strong interaction and decay through the weak interaction (eg kaons)
In what type of interaction is strangeness always conserved?
Strong interactions
What values are conserved in all interactions?
Energy, momentum, charge, baryon number, electron lepton number, muon lepton number
What is the quark composition of K+?
Up, anti-strange
What is the quark composition of K-?
Anti-up, strange
What is the quark composition of K0?
Down, anti-strange
What is the quark composition of anti-K0?
Anti-down, strange
What is the quark composition of π+?
Up, anti-down
What is the quark composition of π-?
Anti-up, down
What is the quark composition of π0?
Up/down/strange, anti-up/anti-down/anti-strange
What are the consequences of electron capture?
The proton-rich nucleus of a neutral atom absorbs an electron from an inner shell, changing a proton to a neutron and emitting an electron neutrino
