Particle Physics Flashcards
What are the main constituents of an atom?
positively charged nucleus (protons, neutrons), electrons
What is meant by specific charge?
Charge to mass ration:
Specific charge = charge / mass
What is the specific charge of a proton?
Specific charge: (1.6 x 10^-19) / (1.67 x 10^-27)
= 9.58 x 10^7 C/kg
What is the letter associated with a proton number?
Z
What is a nucleon?
A constituent of the nucleus: a proton or a neutron
What letter represents nucleon number?
A
What is an isotope?
A version of an element with the same number of protons but a different number of neutrons.
State a use of radioactive isotopes.
Carbon dating - the proportion of carbon-14 in a material can be used to estimate its age
What is the strong nuclear force?
The fundamental force that keeps the nucleus stable by counteracting the electrostatic force of repulsion between protons
Describe the range of the strong force.
Repulsive: up to 0.5 fm
Attractive: 0.5-3 fm
Negligible: >3 fm
What makes a nucleus unstable?
Nuclei which have too many protons, neutrons or both
How do nuclei with too many nucleons decay?
Alpha decay (2p +2n)
How do nuclei with too many protons decay?
Beta- decay ( udd -> uud)
How was the existence of the neutrino hypothesised?
To conserve energy after beta decay, a particle with 0 charge and negligible mass is needed; called the neutrino
What is meant by beta minus decay?
A proton turns to an electron (udd -> uud), the atom releases an electron and an anti-electron neutrino
