Particles P01-07

Question 1

What does the basic structure of an atom look like?

Answer 1

Protons and neutrons within the nucleus, with electrons in the orbit around the nucleus of the atom.

Question 2

What is a nucleon?

Answer 2

A particle in the nucleus, so therefore a neutron or a proton.

Question 3

What is a nuclide?

Answer 3

A nucleus with specific number of protons and neutrons.

Question 4

What is nuclide notation?

Answer 4

Symbol with a number above and below it.
Mass number above it and the atomic number below it.

Question 5

Define specific charge.

Answer 5

The specific charge of a particle is the ratio of its charge per unit mass.

Question 6

How can isotopic data be used within archaeology?

Answer 6

Carbon dating, the amount of radioactive carbon-14 in things decays once it dies, therefore less means older.

Question 7

How can isotopic data be used within forensic?

Answer 7

From drinking water that has natural isotopes, by using a person’s hair you can see their DNA.

Question 8

What’s the range for the strong nuclear forces?

Answer 8

At less than 0.5fm the force is repulsive. Between 0.5-3fm the force is attractive. Beyond 3fm the force is 0.

Question 9

what does a graph of force vs distance for the strong nuclear force look like.

Answer 9

An L shape that curves up to 0 after the bottom of the L shape hits around 0.8fm on the distance axis.

Question 10

What is an alpha particle?

Answer 10

A helium nucleus emitted by some radioactive substances, originally regarded as a ray. The mass number goes down by 4. The atomic number goes down by 2. Large nuclei.

Question 11

What is a beta particle?

Answer 11

A high speed/energy electron or positron emitted by the radioactive decay of a nucleus, beta +/-. As a result of too many neutrons.

Question 12

Why did Pauli propose the existence of the neutrino?

Answer 12

Pauli suggested that if a non-interacting, neutral particle (a neutrino) were emitted, one could recover the conservation laws. To conserve angular and energy momentum.

Question 13

List the types of e-m radiation in order:
i) Which has the longest/shortest wavelength?
ii) Which has the highest/lowest energy?

Answer 13

i) Radio, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays.
ii) Reverse order than the one above.

Question 14

Show how to convert from eV into joules.

Answer 14

1 eV = 1.602 x 10^-19 J

Question 15

Show how to convert from joules into eV.

Answer 15

J / ev (1.602 x 10^-19) = # eV.

Question 16

What property is the same for both matter and antimatter particles?

Answer 16

The mass and magnitude of its electric charge.

Question 17

Describe the process of annihilation.

Answer 17

A particle and its equivalent antiparticle are both destroyed and their mass is converted into energy in the form of two gamma ray photons. To conserve momentum, the two photons will move apart in opposite directions. As with all collisions, the mass and energy is still conserved.

Question 18

Describe the process of pair production from a photon.

Answer 18

Pair production is when one high energy photon spontaneously turns into a particle - antiparticle pair. The energy of the photon must be at least the total past mass energy of the particle - antiparticle creates.

Question 19

Describe the process of pair production by collision.

Answer 19

When a photon interacts with a nucleus or atom and the energy of the photon is used to create a particle–antiparticle pair.This means the energy of the photon must be above a certain value to provide the total rest mass energy of the particle–antiparticle pair. The minimum energy for a photon to undergo pair production is the total rest mass energy of the particles produced:
Emin = hfmin = 2E

Question 20

How do we differentiate between hadrons and leptons?

Answer 20

Hadrons feel the strong and weak nuclear force and are composed of quarks. Leptons are light particles with no structure and feel only the weak nuclear force.

Question 21

How do we differentiate between baryons and mesons?

Answer 21

These are hadrons. Baryons consist of 3 quarks, mesons have a quark and an anti-quark.

Question 22

Which quantities are always conserved in particle processes?

Answer 22

Energy, momentum, bayron number and charge.

Question 23

When might strangeness not be conserved?

Answer 23

It is conserved in strong interactions and electromagnetic interactions but not in weak interactions.

Question 24

State the quark composition of a proton and neutron.

Answer 24

Proton = uud. Neutron = udd.

Question 25

State the quark composition of the pi-mesons: π+;

Answer 25

π+: ud^-

Question 26

State the quark composition of the pi-mesons: π0;

Answer 26

π0: d u/d^-

Question 27

State the quark composition of the pi-mesons: π-;

Answer 27

π-: du^-

Question 28

State the quark composition of the K-mesons:
K⁺;

Answer 28

K⁺: us^-

Question 29

State the quark composition of the K-mesons:
K⁰;

Answer 29

K⁰: ds^-

Question 30

State the quark composition of the K-mesons:
K⁰;

Answer 30

K⁰; d^-s

Question 31

State the quark composition of the K-mesons:
K⁻;

Answer 31

K⁻: u^-s

Question 32

Write down the equation for the beta decay of a proton:
Including charge, baryon number and leptons.

Answer 32

n = p + e^- + ve^-
Q: 0= 1 - 1 + 0
B: 1 = 1 + 0 + 0
Le: 0 = 0 + 1 - 1

Question 33

Write down the equation for the beta decay of a neutron:
Including charge, baryon number and leptons.

Answer 33

p = n + e^+ + ve
Q: 1 = 0 + 1 + 0
B: 1 = 1 + 1 - 1
Le: 0 = 0 - 1 + 1

Question 34

Write down the equation for muon decay (both μ- and μ+).

Answer 34

u^- = e^- + ve^- + vu

u^+ = e^+ + ve + vu^-

Question 35

What are the exchange particles for the e-m, strong and weak interactions?

Answer 35

Weak interactions - W+, W- bosons.
EM interaction is the photon.
Strong interactions is the gluon
Gravity is the graviton.

Question 36

What is electron capture?

Answer 36

Electron capture is an example of a weak interaction where an electron is absorbed by a proton within a nucleus. The proton decays into a neutron and a W+ exchange particle interacts with the electron forming an electron neutrino.

Question 37

Diagrams for particle interactions:
β- decay

Answer 37

Nucleus to a proton, with a W^- boson and an electron and an electro neutrino.

Question 38

Diagrams for particle interactions:
β+ decay

Answer 38

Proton to a nucleus, with a W^+ boson and an positron and an electro neutrino.

Question 39

Diagrams for particle interactions:
electron capture

Answer 39

Proton and electron collision and a neutron off of the proton and a anti neutrino off of the electron.
W^+ boson from left to right, proton to electron side.

Question 40

Diagrams for particle interactions:
electron-proton collision

Answer 40

Proton and electron collision and a neutron off of the proton and a anti neutrino off of the electron.
W^- boson from right to left, proton to electron side.

Question 41

How does a PET scanner work?

Answer 41

Positron emitting isotope is put into a patient’s bloodstream. The positron meets and annihilates with an electron producing gamma photons that are then detected.

Question 42

What does strangeness mean?

Answer 42

Describes the decaying of particles in strong and electromagnetic interactions which occur in a short period of time.

Question 43

What are cosmic rays made up of?

Answer 43

90% protons
10% alpha particles

Question 44

What force is used to differentiate between leptons and hadrons?

Answer 44

Hadrons can feel the strong force, while leptons can’t.

Question 45

Due to cosmic rays what does a Muon decay to?

Answer 45

Electrons

Question 46

Due to cosmic rays what does a Pion decay to?

Answer 46

Muons

Question 47

Due to cosmic rays what does a Kaon decay to?

Answer 47

Pions

Question 48

What does a Kaon, Pion, Muon all have in common?

Answer 48

All lighter than a proton.