Particle Physics - particle detectors and particle tracks

Question 1

What does a cloud chamber consist of?

Answer 1

Super Saturated Air

Question 2

Why is Super Saturated Air used?

Answer 2

• Ionisation of the air happens

- This causes tiny water drops

Question 3

What does a bubble chamber consist of?

Answer 3

Super Saturated Liquid Hydrogen

Question 4

Why is Super Saturated Liquid Hydrogen used?

Answer 4

• Ionisation of the liquid hydrogen happens

- This causes tiny hydrogen gas bubbles

Question 5

What one thing do both types of the particle detectors have in common?

Answer 5

Both have magnetic fields acting through them

… so we can distinguish the different charges (+/-) of the particles

Question 6

What type of subatomic particles do not appear on the particle tracks diagrams? Why?

Answer 6

Neutrons / neutrally charged particles

Because they are neutrally charged so they do not interact with the electrons in the air/liquid hydrogen

Question 7

Einstein’s equation gives us ΔE = c^2 x Δm.

Rearrange the equation to make mass the subject and show that kg = J s^2 m^-2

Answer 7

• ΔE = c^2 x Δm
• ΔE / c^2 = Δm
• ΔE / (speed of light)^2 = Δm
• ΔE / (s / t)^2 = Δm (speed = distance / time)
• ΔE / (s^2 / t^2) = Δm (expand using power)
• ΔE x (t^2 / s^2) = Δm (keep, flip, change)
• ΔE x t^2 / s^2 = Δm
• J s^2 / t^2 = kg (change into units)
• J s^2 t^-2 = kg

Question 8

What is the radius of the tracks proportional to, when interpreting particle tracks?

Answer 8

The RADIUS of the particle tracks are proportional to the MOMENTUM of the particle.

Question 9

What three things are always conserved in collisions, when interpreting particle tracks?

Answer 9

• Momentum
• Mass-energy
• Charge

Question 10

What does the start of particle tracks show?

Answer 10

That particle has collided with another particle in the cloud/bubble chamber.