3. Nuclear Shapes and Sizes

Question 1

What is the equation for scattering?

Answer 1

w_r = J N σ_R
J - Flux of beam = No. particles x v for a stationary targer
N - Number of targer nuclei
σ_R - Reaction cross section

Question 2

What is the unit of cross section?

Answer 2

Measured in barns

1b - 10^-28 m^2

Question 3

How do we solve for charge distribution

Answer 3

Iterative process:

1. Assume f(r) - Charge distribution
2. Calculate expected cross section
3. Compare to measurement, and adjust f(r) if they don’t agree

Question 4

How is the charge distributed across a nucleus?

Answer 4

Relatively uniformly

Question 5

Describe the shape of a charge density-radial distance graph for an atom

Answer 5

Light: Sharp spike then quick decay towards 0
Heavy: Continues flat for longer, then falls to 0 less quickly

Question 6

What is the equation for the nuclear radius?

Answer 6

R = 1.21 A^1/3

Question 7

What do we use to probe neutrons and why?

Answer 7

Neutrons as electrons and neutrons dont interact via EM force with each other

Question 8

What is the problem using neutrons to probe neutrons?

Answer 8

They scatter via the strong interaction off of protons and neutrons