3.2.1.5 Particles and Radiation: Classification of particles Flashcards

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1
Q

What are hadrons?

A

The only particles that can feel the strong nuclear force.
They are not fundamental particles.
Made up of smaller particles called quarks.
Two types; baryons and mesons (classified according to the number of quarks that makes them up)

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2
Q

What are the properties baryons?

A

All baryons (except a free proton) can be unstable - meaning that all baryons decay to become other particles. The particle a baryon decays into depends on what it started as.

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3
Q

What is baryon number?

A

A quantum number that must be conserved - basically the number of baryons
Baryons have baryon number 1
Antibaryons have baryon number -1
Other particles have baryon number 0

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4
Q

What happens to the baryon number in a particle interaction?

A

The total baryon number in any particle interaction never changes

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5
Q

What causes beta decay?

A

Weak interaction

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6
Q

Describe neutron decay

A

n -> p + e- + electron antineutrino

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7
Q

When does beta-minus decay happen?

A

When there are many more neutrons than protons in the nucleus

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8
Q

What are mesons?

A

Interact with baryons via the strong force.
All mesons are unstable and have baryon number 0.
You can get loads of mesons in high energy particle collisions.
Made up of a quark and antiquark
A type of baryon

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9
Q

What are some types of mesons?

A

Pions
Kaons
Others

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10
Q

What are kaons?

A

Heavier and more unstable versions of pions. They have a very short lifetime and decay into pions.

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11
Q

What are pions?

A

The lightest mesons. The pi- meson is the antiparticle of the pi+ meson. They are the exchange particles of the strong nuclear force.

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12
Q

What are cosmic ray showers?

A

High energy particles from space, they are constantly hitting the Earth and often interact with molecules in the atmosphere to produce showers of lots of high energy particles. The tracks of these particles can be observed with a cloud chamber.

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13
Q

How can cosmic ray showers be detected?

A

Using two Geiger counters placed one above the other, separated by absorbing lead. If both detect radiation simultaneously, its likely that a particle from a cosmic ray shower has been detected

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14
Q

What are leptons?

A

Fundamental particles.
Don’t feel strong nuclear force.
Only interact with other particles via weak interaction.

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15
Q

What are muons?

A

Fat electrons - they are unstable and eventually decay into ordinary electrons (stable)

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16
Q

What are neutrinos?

A

Have (almost zero mass) and zero electric charge.
Only take part in weak interactions

17
Q

What is lepton number?

A

A quantum number that must be conserved.

18
Q

What particle is the only stable baryon?

A

Proton

19
Q

What are strange particles?

A

Created via strong force interaction, in which strangeness is conserved.
The conservation of strangeness means that strange particles means that strange particles can only be created in pairs.

20
Q

What is strangeness?

A

A quantum number.

21
Q

What is the strangeness of all leptons?

A

0

22
Q

How do strange particles decay?

A

Through weak interaction
- strangeness is not conserved in weak interaction