4. Charged Particles

Question 1

What’s the difference between charged particles and neutral radiations?

Answer 1

Charged particles- electrons, muons, pions, protons, Alphas, heavy ions, etc. charged particles undergo continuous collisions along their paths and lose energy in a continuous way

Neutral radiations- neutrons, neutrinos, and photons. Neutral radiation’s undergo random collisions in a discontinuous manner and their energy loss is not continuous

Question 2

How do heavy and light charged particles differ in their energy loss through a medium?

Answer 2

Heavy particles have a simple energy loss mechanism as they move they lose energy undergoing elastic and inelastic collisions with atoms and molecules in the medium and ionizing them.
Charged particles other than electrons are heavy ones

Question 3

What is the Bethe formula?

Answer 3

Describes ionization loss and ranges of heavy charged particles for speeds up to about v=0.99c
-dE = energy loss
dx= distance traversed
ze = charge of particle 
βc = speed
Kinetic energy = (γ-1)mc^2
γ=1/(squareroot)1-B^2

Question 4

What is minimum stopping power?

Answer 4

Stopping power is very high for low β
For increasing speeds, the stopping power decreases, reaching a minimum at about β=0.95 or βγ=3
At minimum stopping power particles lose the least amount of energy
Example page 100

Question 5

What is the losing energy of a particle (-dE/dx) proportional to?

Answer 5

Z/A (atomic # over mass #) fractional weight of the element
ρ (density of medium)
ζ (ionic state)
1/β^2 (higher speed of particle, less energy loss)

Question 6

What is the Bragg peak?

Answer 6

The Bragg peak is the maximum energy loss in a short distance which occurs at the end of the particle trail
Energy loss distribution graph shows this
For energies below minimum ionization, energy loss increases as the energy of a particle decreases
Page 108 graph

Question 7

What is the advantage of density thickness as a medium parameter?

Answer 7

In this form, the stopping power does not depend on the physical state (gas, solid, liquid) if the medium

Question 8

What weighted particles have deeper interior Bragg peeks in an admixture of particles from different species all with the same kinetic energy?

Answer 8

Lighter particles have the Bragg peak in deeper interiors