Lecture 2 Flashcards
Intensity change eqn
∆I=στNI
Macroscopic cross sectition eqn and definition
Σ=σN
Interaction probablity per unit thickness
Reaction rate per unit volume eqn
Intensity at x eqn
Probablity to reach x without collision
Probablity to make first collision in dx, around x
probablity to collide at x * probablity to collide within dx
Mean free path def and eqn
average distance neutron travels w/o collision, 1/Σ
Neutron flux for mono speed and direction
φ = I = nv
Flux from point source (geometric only)
Attenuation of flux from point source (geometrically and collissions)
Geometric flux * I(x)
Number density equation
Absorption at a specific E eqn
The energy dependency of the cross sections in the vicinity of each resonance take the form of
the Briet-Wigner formula
Resonances correspond to what?
Excitetation of nuclear levels from the incient neutron.
Define Doppler Broadening
The broadening of resonance peaks due to the change in relative velocity between the neutron and the incident nucleus.
P(V)dV is…?
the probablity that a nuclus has velocity V within dV
Reaction rate
Why threshold cross sections?
The incident neutron needs to have enough kinetic energy to raise the nucleus to an excited state
What is the equation for E’ min
Nameless alpha = ?
What is the equation for the energy distribution of a scattered neutron?
What is the slowing down decrement? (definition)
lograrithmic energy loss per colission
What is the equation for the slowing down decrement?
Aproximately 1/(A+2/3)
or
What is the equation for the number of elastic collisions required to slow a neutron from fission (E_0) to thermal energy(E_n)?
What is the equation for the AVERAGE slowing down decrement?
Slowing-down power is given by…?
The slowing-down ratio is given by…?
