Week 2: Electron scattering from nuclei - the electric Form Factor Flashcards
What is the formula for electron energy in MeV?
E = 2pi x 197.3 x 1/lambda
What is the equation for the first minimum of a diffraction pattern from a black disk/aperture?
sin(theta) = 1.22 x lambda x 1/D,
where D is the diameter of the disk.
What is the integral that describes scattering and what does each part of the integral mean?
(4)
The action of the potential, V(r), on the incoming wave perturbs the wave transmuting it to a new wavefunction (say phi).
The ‘matrix element’ mif is here the “matrix element of the transition operator V(r).
mif “picks out” the amplitude of the final wavefunction, the scattered component (in phi).
How is the scattered intensity related to mif?
The scattered intensity is given by the modulus squared of this amplitude.
(5)
Explain how we get the “momentum transfer” ?
(6)
hq/2pi is the actual momentum transfer to the nucleus*
What does the assumption that the process is quasi-elastic result in?
This means we neglect the energy associated with the recoil of the nucleus in our considerations.
Evaluate mif in terms of the momentum transfer. State any assumptions.
(7)
Using a plane wave appriach for electron scattering show that for elastic scattering the momentum transfer is given by q = 2Ksin(theta / 2).
(7a)
What is the electric of factor?
The electric form factor of the nucleus is the Fourier transform of the nuclear charge density.
Give details of the electric form factor and what is is.
The electric form factor of the nucleus is a function of the internal nuclear coordinates r’ and contains all details of the extended charge distribution of the particular nucleus and none of the details of the electron coordinates r in electron scattering.
