Particles

Question 1

What is the ‘specific charge’?

Answer 1

The value of charge (in coulombs) divided by mass (in kilograms). Units are coulombs per kg

Question 2

What is an ion?

Answer 2

An atom with has gainer or lost electrons

Question 3

What is the strong nuclear force?

Answer 3

Acts between nucleons
Works at very short distances - attractive at 3fm
Repulsive at 0.5fm so the nucleus doesn’t collapse on itself

Question 4

What is given off during alpha radiation?

Answer 4

An alpha particle (a helium nucleus)

Question 5

What is beta minus radiation?

Answer 5

A neutron decays into a proton, emitting an electron (beta- particle) and an electron anti-neutrino.
Occurs via the weak interaction and a W- boson is exchanged

Question 6

What is beta plus decay?

Answer 6

A proton decays into a neutron, emitting an electron neutrino and a positron (beta+ particle)
Occurs via weak interaction and a W+ boson is exchanged

Question 7

What is electron capture?

Answer 7

An electron is absorbed by a proton in the nucleus, which produces a neutron and an electron neutrino.
Occurs via weak interaction and a W+ boson is exchanged

Question 8

What is electron-proton collision?

Answer 8

An electron collides with a proton outside the nucleus, emitting a neutron and an electron neutrino.
Occurs via weak interaction and a W- boson is exchanged

Question 9

Describe the properties of hadrons

Answer 9

Subject to the strong interaction
Divided into baryons (+antibaryons) and mesons
Baryon number as a quantum number. Conserved
Proton is only stable baryon winto which other baryons eventually decay
Pion is exchange particle of the strong nuclear force

Question 10

Describe the properties of leptons

Answer 10

Subject to weak interaction

Lepton number as a quantum number. Conservation of lepton number for muon leptons and for electron leptons

Question 11

What is a fundamental particle?

Answer 11

A particle which can’t be divided into anything smaller

Question 12

Describe strangeness

Answer 12

Must be the same before and after in strong and electromagnetic but not weak interactions
In weak interactions the strangeness can change by 0, +1 or -1

Question 13

Describe electromagnetic interaction

Answer 13

Experienced by all particles.
Infinite range
Photon is exchange particle

Question 14

Describe gravitational interaction

Answer 14

Experienced by all particles with mass.
Infinite range
Exchanged particle is graviton

Question 15

Describe gravitational interaction

Answer 15

Experienced by hadrons.
Range about 3x 10^-38m
Exchange particle is gluon

Question 16

Describe weak interaction

Answer 16

Experienced by all fundamental particles.
Range about 10^-18m
Exchange particle is W+, W-, Z boson

Question 17

Describe leptons

Answer 17

Fundamental particle
Cannot take part in strong interactions
All interact by way of weak interaction
Charged leptons can also interact through electromagnetic interactions

Question 18

Describe hadrons

Answer 18

Particles which are made up or quarks and/or antiquarks
Only tupe of particle which can interact via the strong nuclear force.
Divided into baryons, antibaryons and mesons
Baryons are made of 3 quarks.
Mesons are made of a qyak and an antiquark

Question 19

Describe annihilation

Answer 19

When an antiparticle and particle collide they annihilate and form new particles (often photons)

Question 20

Describe pair-production

Answer 20

If a gamma photon with enough energy interacts with a nucleus or an atomic electron, it can disappear and form a particle and antiparticle.