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Physics Paper 1 > 08- Nuclear and Particle Physics > Flashcards

08- Nuclear and Particle Physics Flashcards

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1
Q

8.Use of electric and magnetic fields in cyclotron

A

magnetic - accelerate particles

electric - accelerate particles

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2
Q

8.Particle equation for decay of a proton within a nucleus

A

p -> n + b+ + v

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3
Q
  1. Describe the standard model for subatomic particles
A

Quarks and Leptons are fundamental particles
There are 6 Quarks and 6 Leptons
Baryons are made of 3 quarks or 3 antiquarks
Mesons are made of a quark-antiquark pair
Each particle has an antiparticle

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4
Q
  1. Which of the following particles is a fundamental particle

nucleus
neutrino
pion
proton

A

proton

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5
Q

8.Explain the need for high energy collisions of protons

A

Energy is required to overcome electrostatic repulsion between protons
E=mc^2
Bc c^2 is very large
E must be large

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6
Q

Deduce whether the antineutrino is charged

A

it doesnt leave a track so it is not charged

the charge before decay is -1 and after is -1 +0 so it isnt charge

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7
Q

8.State the groups pions and muons belong to and describe the two groups

A

Muon is lepton
Leptons are fundamental particles
Pion is a meson
mesons consists of a quark antiquark pair

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8
Q

state what is meant by collides elastically

A

total KE conserved

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9
Q

The total mass of the three particles created after this event is larger than the total
mass of the two particles before. Discuss the quantities that must be conserved in
interactions between particles and use an appropriate conservation law to explain
this increase in mass.

A

Momentum conserved
Charge conserved
Energy / mass conserved
E =mc^2
Kinetic Energy is responsible for increase in mass
Momentum of three particles after = momentum of kaon before
Total charge 0 / charge before and after is 0
Conservation of Baryon no, quark no, strangeness

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10
Q

Explain why the fragments of an unstable nucleus shoot out in all directions

A

zero momentum before
to conserve momentum fragments go in all directions
making zero momentum after

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11
Q

State what is meant by the term baryon

A

A baryon is a sub-atomic particle made up of 3 quarks

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12
Q

Condition for a ‘relativistic system’

A

Speeds near the speed of light

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13
Q

Explain why you would expect the initial motion of the particle and antiparticle to be in
opposite directions at the instant at which they are produced

A

momentum conserved
initial momentum zero
⇒ final momentum zero

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14
Q

For each particle, either give its quark composition or state that fundamental particle.

n
p
β
Antiv

A

n - udd
p - uud
β - Lepton
Antiv- Lepton

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15
Q

β– decay

A

n → p + β– + Antiv

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16
Q

β+ decay

A

n → p + β– + v

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17
Q

why high energies are required to investigate the structure of
nucleons

A

nucleons are small
this is because the higher the
energy of matter (such as electrons), the smaller their De Broglie wavelength, and so they are more suitable for investigating smaller
objects as the resolution increases

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18
Q

nucleon number

A

The number of neutrons and protons in the

nucleus

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19
Q

proton number

A

The number of protons in the nucleus

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20
Q

fundamental particles

A

particles that cannot be broken down into any smaller constituent
parts

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21
Q

Hadrons can be classified into mesons and baryons

Describe mesons and baryons

A

Mesons always include a quark-antiquark

Baryons are composed of 3 quarks or 3 antiquarks

22
Q

possible quark composition of a pion minus particle

A

down anti up

23
Q

Pion plus decay to produce two leptons

A

pion plus -> positron + electron neutrino

24
Q

Kaon plus structure

A

up antistrange

25
Q

kaon plus decay

A

kaon plus -> pion plus + pion 0

26
Q

pion structure

A

up antidown

27
Q

Data at the back of the examination paper can be used with the formula ‘ ‘ to
calculate the energy produced when an electron and a positron annihilate

A

‘E=c^2m’

28
Q

Kaons are known to have which quark

A

Strange

29
Q

Kaon quark combination

A

s antiup

30
Q

kaon + quark combination

A

up antistrange

31
Q

K0 quark combination

A

s antidown or d antistrange

32
Q

The total mass of the particles produced in this interaction is greater than the total
mass of the two particles that collided.
Explain this increase in mass.

A

Mass-energy is conserved

colliding particles having mass and kinetic energy

the extra mass comes from the kinetic energy.

33
Q

uAu uAd uAs dAd dAu dAs sAs sAu sAd

A=anti

From the list select the four strange mesons and state the charge and strangeness of
each of them.

A

uAs + +
dAs 0 +
sAu - -
sAd 0 -

34
Q

Some of the mesons have zero charge and zero strangeness.

Suggest what might distinguish these mesons from each other.

A 
Different:
masses
lifetimes
stabilities
decay products
35
Q

Physicists were able to confidently predict the existence of a sixth quark. State why

A

Symmetry of the standard model
Quarks are in pairs in the particle generations
6 leptons known but only 5 quarks

36
Q

How do the properties of a proton and an anti-proton compare?

A

Same mass

Opposite charge

37
Q

After the collision the two top quarks move in opposite directions with the same
speed.
Explain why.

A

Conserve momentum
Initial total momentum is zero
so final total momentum is zero

38
Q

Explain why GeV/c^2 is a valid unit for momentum

A

(G)eV/c^2 is a unit of mass

Momentum is mass x velocity

39
Q

Suggest why it took a long time to find experimental evidence for the top quark

A

top quark has large mass

large amounts of energy required

40
Q

decay of a D0 meson

A

D0 -> kaon plus + pion minus

41
Q

Suggest a possible quark combination of the positively charged kaon.

A

charm antiup

42
Q

Explain what a charge of +2/3 means.

A

2/3 that of a proton / 2/3 x 1.6 x 10-19

43
Q

kaon minus is what type of hadron

A

meson

44
Q

omega minus is what type of hadron

A

baryon

45
Q

Discuss the quantities that must be

conserved in interactions between particles

A

Momentum conserved
Charge conserved
Energy / mass conserved
E =mc

46
Q

Describe the structure of a meson.

A

quark antiquark pair

47
Q

Describe the quark composition of anti-protons and anti-neutrons

A

2x antiup and 1x antidown

2x antidown and 1x antiup

48
Q

State with a reason whether the electrons in an electron beam will produce a suitable diffraction pattern

A

wave length must be similar to the atomic gap spacing

49
Q

When a student compares his correctly calculated values of KE with the measured values in the table, they are
not the same. Explain why.

A

as electrons travel at speeds close to the speed of light their mass increases

relativistic equations such as ke = o.5mv^2 shouldnt be used

50
Q

derive de Broglie wave equation

A

Ke = p^2/2m and λ= h/p

p=2mKE
λ= h/root(2mke)

Physics Paper 1 (5 decks)

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