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Physics > Particles > Flashcards

Particles Flashcards

0
Q

What forces are acting with in a nucleus?

A

Gravity - attracting nucleons together because of there mass.
Electromagnetic - causes + charged protons to repel.
Strong nuclear force - mostly attractive but repels at very small distances.

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1
Q

What are the abbreviations for
Proton number
Nucleon number ?

A

Proton number - z

Nucleon number - A

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2
Q

Describe the strong force

A

A very short range
Repels from less then 9.5 fm
Attracts up to around 3 fm

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3
Q

How many netter is 1 fm?

A

1x10^-15 m

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4
Q

At what distance does the strong force prevent particle colliding?

A

0.5 fm

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5
Q

What is nuclear decay?

A

When an unstable nuclei emits particles to scone more stable.

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6
Q

Why are some nucleases unstable?

A

The strong force has only a small range so large nucleases struggle to stay together. (Alpha decay)
Or
There is a very uneven proton to neutron count. They are neutron rich. (Beta - decay)

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7
Q

When would beta decay happen

A

When a nucleus is too neutron rich

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8
Q

When would alpha decay happen?

A

When a nucleus is too large to be kept stable by the strong force.

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9
Q

What happens in alpha decay?

A

A large nucleus of 82 protons or more emits an alpha particle (a helium nucleus decreasing the protons by 2 and nucleon number by 4.

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10
Q

What happens in beta minus decay?

A

An neutron turns into a print emitting an electron and antineutrino to account for some of the energy. The nucleon number stays the same but the proton number increases.

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11
Q

For every particle there is a corresponding …

A

Antiparticle. Eg electron and positron.

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12
Q

What is the frequency of a wave?

A

The the number of complete oscillations of a wave passing a point per second.

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13
Q

What is a waves wavelength?

A

The distance in meters between two adjacent crests.

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14
Q

What is pair production is when…

A

When there is enough energy to create matter a particle and anti particle are produced.

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15
Q

How do you work out the minimum energy for a pair production?

A

It is 2 x the rest energies

Min E = 2E0

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16
Q

What happens when a particle meets its antiparticle?

A

Annihilation, all the mass is converted back into energy in the form of 2 gamma rays.

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17
Q

What is the minimum energy of one and both of the photons produced by annihilation?

A

1 photon min E = rest mass

Both photon min E = 2xrest mass

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18
Q

Particles that feel the strong force are called …

A

Hadrons

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19
Q

What is the only stable baryon?

A

A proton so all baryons decay to it.

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20
Q

Baryon number is conserved but what is the baryon number for an antiproton?

A

-1

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21
Q

What is neutron decay also known as?

A

Beta decay

22
Q

What interaction is responsible for neutron decay/ beta decay ?

A

The weak force

23
Q

What pions gory do pions fit under?

A

Meson

24
Q

Discribe mesons

A

They are unstable
Have a baryon number 0
They interact with hadrons through the strong force.

25
Q

Name 2 mesons

A

Kaon and pion (the lightest)

26
Q

What forces do leptons feel?

A

Weak interactions, electromagnetic (if charged) and gravity.

27
Q

What category are pions, where are they found, what do they do

A

Mesons, comic rays or high energy collisions, they are involved in the change of neutron to proton and protons into neutrons.

28
Q

What is the lightest meson?
A kaon or a pion?
Name the 3 types.

A

Pion
Pi +
Pi -
Pi 0

29
Q

Name the 3 types of kaons and what category are yet classes under?

A

K+
K -
K 0

30
Q

Name the 4 real leptons needed for the AS.

A

Electron
Muon
Electron neutrino
Muon neutrino

31
Q

What charge does a muon have and what category is it classed under?

A

Muon = U- A negative charge

It is a lepton.

32
Q

What is the lepton number for an antimuon neutrino

A

-1

33
Q

What do you need to remember when calculating the lepton number?

A

That the electron and muon numbers are calculated separately.

34
Q

What are the types of muons?

A

U- (real)

U + (anti)

35
Q

What is the quark structure of a proton?

A

UUD

36
Q

What is the quark structure of a neutron?

A

UDD

37
Q

What is the quark structure of mesons?

A

A quark and an antiquark

38
Q

What is the quark structure of baryons?

A

3 quarks, qqq

39
Q

What properties of quarks are passed on to the particle they make?

A

Charge
Strangeness
Baryon number

40
Q

What is the quark structure do an antineutron?

A

Anti u , anti d, anti d

41
Q

What is the quark structure that make up a pion.

A

A quark and antiquark
Consisting of only up, down, anti up or anti down quarks.
_
1 exception of ss a pi0 pion.

42
Q

What is the quark structure of a kaon?

A

A quark and an antiquark

Must have one strange or anti strange.

43
Q

What are the 3 ways of making a pi 0 pion?

A

UU , DD, SS

44
Q

What property does kaons have that pions don’t

A

Strangeness

45
Q

What happens when you try to remove a quark?

A

The energy used undergoes pair production to make a meson.

And the original quark stays as part of a particle due to quark confinement.

46
Q

What is meant by quark confinement.

A

That is is impossible to isolate a quark by itself.

47
Q

A quark turning into another quark is known as

A

Changing the quark’s character

48
Q

Describe beta plus decay

A 
A proton turns to a neutron 
It happens in isotopes with too few neutrons e.g carbon-11
A positron and neutrino are created.
A U quark changes to a D quark
UUD > UDD
49
Q

In terms of quarks what happens with beta minus decay?

A

UDD > UUD. Neutron to proton

A d quark changes to a u quark.

50
Q

What is the equation for beta + decay?

A

P–> n + (e+) + (Ve)

Via weak interaction

51
Q

What properties are conserved in all particle reactions?

A

Lepton number, Baryon number, charge

52
Q

What property is only conserved with strong force reactions?

A

Strangeness

53
Q

Examples of conservation of charge and baryon number.

A

Pair production
Beta minus decay
Beta plus decay

Physics (12 decks)

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