Nuclear Physics Flashcards
1
Q
What are Hadrons?
A
Are particles that are made up of Quarks
2
Q
Are Hadrons Fundamental particles?
A
No, they are made up of smaller particles called quarks
3
Q
What are the 2 types of Hadrons?
A
- Baryons - Mesons
4
Q
What kind of Hadrons are Protons and Neutrons?
A
Baryons
5
Q
What is the only stable Baryon?
A
The proton
6
Q
What is meant by an Unstable particle?
A
This means that they decay to become other particles
7
Q
What type of Particle do Baryons decay to?
A
All Baryons except protons decay to a proton
8
Q
Antiprotons and antineutrons are examples of what Hadron?
A
Antibaryons
9
Q
What happens when a antiparticle and it’s corresponding particle meet?
A
They annihilated when they meet.
10
Q
What are the antiparticles of Protons and Neutrons?
A
Antiprotons & Antineutrons
11
Q
What is the Baryon number for a Proton and Neutron?
A
+1
12
Q
What is the Baryon Number of an AntiBaryon?
A
-1
13
Q
What is the Baryon number for particles that aren’t Baryons?
A
0
14
Q
The Baryon number is always (………..)
A
Conserved
15
Q
What must be true for a Baryon to interact?
A
The Baryon number on each side of the interaction must be the same
16
Q
How do we know that a Baryon interaction will not happen?
A
If the Baryon numbers are not the same on either side then the particles will not interact
17
Q
The total baryon number in any particle interaction (…………………)
A
Never changes
18
Q
Mesons are another type of what?
A
Hadron
19
Q
Are Mesons stable or unstable?
A
All Mesons are UNSTABLE
20
Q
What is the Baryon number of a Meson?
A
0, because they are not baryons.
21
Q
Are Pions (π) Mesons or Baryons?
A
Mesons
22
Q
What are the three different types of Pions?
A
π⁰ , π⁺ , and π⁻
23
Q
Are Kaons Mesons or Baryons?
A
Mesons
24
Q
What is the difference between Pions and Kaons?
A
Kaons are heavier and more unstable than Pions
25
Hadrons are made up of...
Quarks
26
What is the Baryon number for a Baryon?
+1
27
What is the Baryon number for a Meson?
0
28
Are Nucleons Baryons or Mesons?
Baryons
29
Are Leptons Fundamental Particles?
Yes, they are not made up of anything smaller
30
What is meant by Fundamental Particles?
When something cannot be broken down any further into smaller particles
31
Are Electrons stable or unstable?
Stable
32
What are the two other Leptons we should know?
Muon & Tau
33
What are all the Leptons we should know?
Electrons, Tau & Muon
34
What is the difference between Electrons and Muons & Tau?
Muons & Tau are basically just heavy electrons
35
What are Neutrinos?
Have zero mass and zero charge
36
Show the Lepton numbers for the 6 different leptons.
37
Are Photons made of Quarks?
No
38
Are Photons made of Leptons?
No
39
What is a Photon?
A particle of light
40
What is the symbol of a photon included in a interaction?
γ
41
Does a Photon have mass?
No
42
Does a Photon have charge?
No
43
Does a Photon have a Baryon number?
No
44
Does a Photon have a Lepton number?
No
45
What does a photon have then??
It has ENERGY
46
What did J.J Thompson discover / deduce?
Discovered electrons could be removed from the atom
He suggested atoms were spheres of positive charge with tiny negative electrons stuck in them like the fruit of a ‘plum pudding’.
He created the ‘Plum Pudding’ model
47
Who did Rutherford’s experiment disprove?
Disproved Thomson’s ‘Plum Pudding Model’
48
What was Rutherford’s scattering experiment?
- He fired alpha particles at a very thin gold foil.
- When the alpha particles hit a fluorescent screen, a tiny visibility flash of light is produced. They recorded these flashes and counted the number of alpha particles scattered at different angles. (view image)
- If the Thomson model was right, all the flashes should have been seen within a small angle of the beam. They didn’t see this.
- They noticed that some alpha particles scattered at angles greater than 90 degrees
49
What did John Dalton discover?
Said matter was made up of tiny spheres That couldn’t be broken up.
50
What were the Conclusions of Rutherford’s experiments?
- Most alpha particles went straight through the the foil, so the atom is mostly empty space.
- Some alpha particles were deflected so the centre of the atom must have a large, positive charge to repel them.
- Very few particles were deflected so the nucleus is small
- There must be mass in the nucleus, because the particles were deflected by angles greater than 90 degrees.
51
The nuclear model explained...
Rutherford Scattering
52
Nuclear Model - Nucleus Charge and Structure.
Inside every atom, there’s a positive nucleus containing neutrons and positively charged protons.
53
Nuclear Model - what charge do neutrons have?
They don’t have a charge
54
What are Protons and Neutrons both known as?
Nucleons
55
What orbits the core of the Nucleus?
Negatively charged electrons
56
What is the charge on an Electron?
-1.6 x 10\*-19
57
Is the nucleus of an atom big or small?
Really small!
58
Most of the atom is...
Empty space
59
Which part of the atom is the most MASSive?
The Nucleus
60
What is the Proton Number?
Is the number of protons in the nucleus
61
What is a Proton number also called?
Atomic Number
62
It’s the (.................) that defines the element?
Proton number
63
What makes an atom stable / neutral?
Same amount of protons and electrons
64
In a neutral atom what must be true?
The number of electrons equals the number of protons
65
What is the Nucleon Number also known as?
Mass Number
66
What is the Nucleon number?
Is the total number of Protons and Neutrons
67
Each proton and neutron has a mass number of...
1
68
What is the mass of an electron?
0
69
What is the number 6 shown here?
Proton number or atomic number - shows the number of protons in an atom
70
What is the number 12 shown here?
Nucleon number & mass number - total of 12 protons and neutrons
71
What are Particle Accelerators?
Devices that accelerate particles, using electric and magnetic fields
72
Forces act on (....................) in Magnetic Fields
Charged Particles
73
What is Electric Current caused by?
Caused by the flow of negatively charged electrons
74
Why does a Current carrying wire feel a force in a magnetic field?
Electric current in a wire is caused by the flow of negatively charged electrons, these charged particles are affected by magnetic fields.
75
What is the equation for the force exerted on a current carrying wire in a magnetic field perpendicular to the wire carrying it?
F = BIL
B - Magnetic Flux Density
I - Current
L - Length of the wire
76
Derive the equation F = BQv
F = BIL
USE - I = Q / t
v = l / t
It creates the equation - I = Qv / L
Put F = BIL and I = Qv / L together
Creates - F = BQv
77
What do the components of F = BQv stand for?
F - Force (N)
B - Magnetic Flux Density (T)
Q - Charge (C)
v - velocity of charged particles (ms\*-1)
78
What can equation can you use to find the force acting on a single charger particle moving through a magnetic field?
F = BQv
F - Force (N)
B - Magnetic Flux Density (T)
Q - Charge (C)
v - velocity of charged particles (ms\*-1)
79
Charged Particles in a Magnetic Field are deflected in a (....................)
Circular Path
80
What is Fleming’s Left Hand Rule?
81
Is this a Magnetic Field INTO or OUT of the page?
INTO the page
82
Is this a Magnetic Field INTO or OUT of the page?
OUT of the page.
83
For uniform circular motion Newton’s Second Law gives...
F = mv\*2 / r
84
What is the equation that links charged particles following a circular path in a magnetic field?
BQv = mv\*2 / r
85
How do we get the equation r = p / BQ ?
BQv = mv\*2 / r
86
Rearrange, cancelling and substituting in p = mv
r = p / BQ
87
What is the equation that shows the radius of a charged particle in a magnetic field?
r = p / BQ
r - radius of the circular path
p - Momentum of the particle
B - Magnetic Flux Density
Q - charge of the particle
88
What are cyclotrons used in?
Medicine, radiotherapy
89
What is a Cyclotron made up of?
Is made up of two hollow semicircular electrodes
90
What is a Cyclotron made up of?
Made up of two hollow semi circular electrodes with a uniform magnetic field applied perpendicular to the plane of the electrodes, and an alternating P.D between the electrodes
91
How does a Cyclotron work?
- Charged particles are fired into one of the electrodes, the magnetic field makes them follow a semi circular path and then leave the electrode.
- An applied P.D between the electrodes accelerates the particles across the gap until they enter the next electrode.
- As the particles momentum increases it follows a circular path with a larger radius, before leaving the electrode again
- The P.D is reversed so the particle is accelerated again before entering the next electrode.
92
What is the equation showing the Kinetic Energy a particle with charge gain when it is accelerated through a P.D of V Volts?
E = QV
E - Kinetic Energy (JC\*-1)
Q - Charge
V - P.D of accelerator voltage
93
Define an electron Volt in words.
An electron volt is the Kinetic Energy carries by an electron after it has been accelerated through a P.D of 1V
94
Define an Electronvolt through equations.
Put E = 0.5mv\*2 equal to E = QV
0.5mv\*2 = QV
Q = charge of an electron so...
0.5mv\*2 = eV
95
What is the Electronvolt conversion factor?
1 eV = 1.6 x 10\*-19
96
What does LINAC stand for?
Linear Particle Accelerator
97
What are LINACs ?
Is a long straight tube containing a series of tube shaped electrodes. The charge on each electrode alternates along the tube ( so a positive electrode is always between two negative electrodes)
98
How do LINACs work?
- Electrodes are connected to an alternating P.D supply so that the charge of the electrodes is constantly changing between + and -. So the electric field between each pair of electrodes is constantly switching.
- The alternating P.D is timed so that the particles are always attracted to the next electrode, and repelled from the previous one.
- Particles speed increases as it passes through each one.
99
Why do the electrodes increase in length?
Because the particles increase in speed the length of the electrodes increases as the particle travels down the accelerator, so that the particle spends the same amount of time in each electrode.
