6. Scattering Flashcards
What is the purpose of scattering experiments?
To explore the properties of a nucleus.
Define the total scattering cross section
The sum of elastic and inelastic processes.
Give the equation for the total scattering cross section
Elastic scattering involves processes whose incident particles have ___ _____ initial and final energies.
The same
Inelastic scattering involves processes in which _______ _____ occurs.
Energy loss
Define the total interaction cross-section
The sum of scattering and absorption cross sections.
Give the equation for the total interaction cross section
Beam flux through thin target is attenuated with __________ decay.
Exponential
Define incident flux
For a parallel beam of particles incident on a target, it is the number of incident particles per unit area per unit time passing perpendicular to the beam direction.
Give the equation for the interaction probability
What is the interaction probability equivalent to?
The fractional change in flux
Give the equation for the fractional change in flux
dI = change in flux
I = flux
n = number density of target particles per unit volume
A = area
dx = target thickness
σ = cross-section
Give the equation for the flux
I = flux
I0 = incident flux
n = number density of target particles per unit volume
σ = cross-section
x = position
Give the equation for the number of particles that have undergone an interaction
I_tot = number of particles that have undergone an interaction
I0 = incident flux
I = flux
n = number density of target particles per unit volume
σ = cross-section
x = position
What is the scattering cross section?
A value that encodes the probability that a particle is scattered. It doesn’t give information about the direction of scattered particles.
Why is it important to know the direction of a scattered particle?
It gives important information about the properties of the target particle (e.g. the shape of the nuclear potential).
State the conversion from Cartesian coordinates to spherical polar coordinates
Describe a volume element in spherical polar coordinates
Define the differential cross section
The fraction of particles scattered into dΩ for a target with n particles per unit volume and thickness, t.
What does the differential scattering cross-section say about a particle?
It gives information on the direction of scattered particles.
Give the equation for the fraction of particles scattered in dΩ
Give the equation for the differential scattering cross section
dσ = change in cross-section
dΩ = scattering position
State the relation between the differential cross-section and total scattering cross-section
How can the total cross-section be found?
It can be obtained from the attenuation through a target.
How can the total scattering cross-section be found?
It can be obtained by detecting all the particles scattered out of the beam direction.
What is the impact parameter?
The distance at which incident particle would pass by the target if there were no interaction, denoted by the symbol b.
Equate the differential scattering cross section to the impact parameter
The impact parameter can be related to the differential cross-section for problems with __________ symmetry.
Azimuthal
What are WIMPs?
Weakly interactive massive particles: they are a candidate for dark matter
Describe the Rutherford differential scattering cross-section
