130_notes.dvi

(Frankie) #1

With just theℓ= 0 term, the differential scattering cross section is.



dΩ


sin^2 (δℓ)
k^2

The cross section will have zeros when


k′
k

= cot(ka) tan(k′a)
k′cot(k′a) =kcot(ka).

There will be many solutions to this and the cross section will look like diffraction.


there will be many solutions to this


log σ


E


diffractive scattering


15.8 The Radial Equation foru(r) =rR(r)*.


It is sometimes useful to use
unℓ(r) =rRnℓ(r)


to solve a radial equation problem. We can rewrite the equation foru.
(
d^2
dr^2


+

2

r

d
dr

)

u(r)
r

=

d
dr

(

1

r

du
dr


u
r^2

)

+

2

r^2

du
dr


2 u
r^3

=

1

r

d^2 u
dr^2


1

r^2

du
dr


1

r^2

du
dr

+

2 u
r^3

+

2

r^2

du
dr


2 u
r^3

=

1

r

d^2 u
dr^2
1
r

d^2 u(r)
dr^2

+

2 μ
̄h^2

[

E−V(r)−

ℓ(ℓ+ 1) ̄h^2
2 μr^2

]

u(r)
r

= 0

d^2 u(r)
dr^2

+

2 μ
̄h^2

[

E−V(r)−
ℓ(ℓ+ 1) ̄h^2
2 μr^2

]

u(r) = 0

This now looks just like the one dimensional equation except the pseudo potential due to angular
momentum has been added.


We do get the additional condition that
u(0) = 0


to keepRnormalizable.

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