3.2 Particles and radiation

Question 1

what is the proton and nucleon number and and their symbols

Answer 1

Nucleon number is the total amount of protons and electrons(A)
Proton number(Z)
altogether this is called nuclide notation

Question 2

define an isotope

Answer 2

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, hence differ in relative atomic mass but not in chemical properties

Question 3

what is specific charge

Answer 3

specific charge, also referred to as charge to mass ratio charge/mass in kg C*-1

Question 4

what is a strong nuclear force and its role

Answer 4

a strong nuclear force is the opposing force against electrostatic forces which keeps protons and neutrons together

Question 5

describe the effect of a strong nuclear force and how it works

Answer 5

The strong nuclear force is repulsive below 0.5 fm, and attractive up to 3 fm, before approaching zero no effect at large separations.

Question 6

what is a neutrino

Answer 6

A neutrino is a subatomic particle that is very similar to an electron, but has no electrical charge and a very small mass, which might even be zero.

an uncharged lepton with very low rest mass compared with the electron

Question 7

what is the exchange particle in beta minus decay

Answer 7

w - boson for beta minus
w + boson for beta plus decay
exchange particles are essentially there to let the other particle know there is another particle is there - must be there for repulsion to occur

Question 8

why was the existence of the neutrino discovered

Answer 8

The existence of the neutrino was hypothesised to account for conservation of energy in beta decay.

Question 9

beta minus and plus decays

Answer 9

beta minus - neutron decay into proton (w-)
beta plus - proton decay into neutron (w+)

Question 10

what is annihilation

Answer 10

When a particle meets its equivalent anti–particle they both are destroyed and their mass is converted into energy in the form of two gamma ray photons - the photons are to conserve momentum

Question 11

Pair production is

Answer 11

When a photon interacts with a nucleus or atom and the energy of the photon is used to create a particle–antiparticle pair

Question 12

which exchange particle in the weak interaction and electromagnetic interaction

Answer 12

weak interaction uses w bosons whereas the electromagnetic interaction(eg em repulsion) uses photons

Question 13

describe pair production

Answer 13

In pair production a photon creates a particle antiparticle pair since the energy gets converted into matter and anti matter in the form of a photon

the minimum energy of a photon to undergo pair production is the total rest energy of the particles produced

Question 14

What is 1 fm in m?

Answer 14

10⁻¹⁵ m

Question 15

How strong is the weak force?

Answer 15

1 millionth(1/100000) the value of the strong force

Question 16

What happens if the nucleus is still unstable after emitting alpha or beta radiation?

Answer 16

It is in an excited state, and gives off gamma radiation

Question 17

What does an electromagnetic wave consist of?

Answer 17

An electric wave and a magnetic wave which travel together in phase

Question 18

How do photons travel?

Answer 18

In one direction only in a straight line

Question 19

electron capture equation

Answer 19

P + -e —-> n + electron neutrino
(w+ boson is the exchange particle

Question 20

which interaction effects which particles and what is the exchange particles(guage bosons)

Answer 20

EM - virtual photon and effects only charged particles
Weak - W+/- and effects all particles eg electron capture/electron proton collisions
strong - pions(gluons) π+/-/0 and only effects hadrons

Question 21

What are hadrons?

Answer 21

Particles that feel the strong nuclear force. They are not fundamental since theyre made up of quarks

Question 22

What is a virtual particle?

Answer 22

Particles which exist for only a very short time and cannot be detected.

Question 23

What is the difference between the 2 hadrons (baryons and mesons?)

Answer 23

• Baryons - Made of 3 quarks and decay into a proton directly or indirectly
• Mesons - Made of a quark and antiquark and do not decay into a proton

Question 24

What is the only stable baryon?

Answer 24

Proton - this means all baryons will decay in sequence and eventually form a proton.

Question 25

what are leptons and examples

Answer 25

fundamental particles that dont feel the strong nuclear force and only interact with other particles via weak interactions, they arent stable
Eg: electron , electron neutrino , muon and muon neutrinos , tau

Question 26

muons are

Answer 26

leptons around 200x heavier than electrons so are unstable and will eventually decay into an electron

Question 27

what is strangeness

Answer 27

like baryon number its a quantum number so it can only take a certain set of values
strange particles eg kaons are created via the strong interaction but decay via the weak interaction

strangeness is conserved in the strong interaction but is not conserved in the weak interaction

so strange particles are always produced in pairs eg k+ and k-

Question 28

a weak interaction is

Answer 28

something which changes the quark type eg proton into neutron changes uud into udd

Question 29

what are the 4 conserved properties in particle interactions

Answer 29

charge , baryon numbers , strangeness(only in strong interactions)
lepton numbers are conserved differrently, electron lepton number and muon lepton number is conserved

Question 30

decay of a neutron equation

Answer 30

n —> p + e- + anti electron neutrino

Question 31

which mesons are strange

Answer 31

kaons

Question 32

how are particles discovered

Answer 32

1. New theories created to explain observations from experiments , hypothesising a particle and properties they expect it to have
2. experiments are carried out to find the existence of the particle and if the experiments confirm the theories and the scientific community accept it its validated
3. but particle physics experiments often need particle accelerators which are expensive to build and run and many scientists would need to collaborate to fund them

Question 33

how to convert from MEV into joules

Answer 33

x 1.6 x10*-13

Question 34

what is electron capture

Answer 34

an electron interacting with a proton in the nucleus (via weak interaction) to form a neutron by changing the u into d quark and a neutrino released

Question 35

in the interaction between protons in the nucleus what is it called and what is the exchange particle

Answer 35

electromagnetism
uses photons as the exchange particle

Question 36

what is the exchange particle for the strong nuclear force

Answer 36

the gluon