### The Compton Effect

```DO NOW (3/7/14):
1.
What is a photon?
2.
What are some
characteristics of photons?
3.
Does light interact with
matter as a particle or a
STRAIGHT
OUTTA
COMPTON
THE COMPTON
EFFECT
3/7/14
THE COMPTON EFFECT (COMPTON SCATTERING)
 The
Compton effect is a form of ionization.
 What
is an ion?
An ion is an electrically charged atom or group of
atoms.
Compton Scattering ionizes particles through the
emission of an electron
APPLICATION

How can this be used?
- Particle Accelerators
- CT Scans /
X-rays
- Ion Propulsion
Engines
THE COMPTON EFFECT
 Result
of a high-energy photon
colliding with a target.
THE COMPTON EFFECT (COMPTON SCATTERING)
phy/Graphics/Flash/compton.swf

 The
electron is irradiated with a photon.
 The
Scattered Photon comes off as
THE COMPTON EFFECT (COMPTON SCATTERING)
 This
lends support to Einstein's
photon theory, rather than wave
theory.
 Compton
Scattering was first
demonstrated in 1923 by Arthur
Holly Compton.
 Scattered
wavelength shift. X-rays increase in
wavelength when scattered.
How does the wave for the incident photon
compare to that of the scattered photon?
COMPTON SHIFT: (WRITE ON BACK)
Is the change in wavelength
of scattered photon
h
   ' =
(1- cos )
m0c
 '- = c (1- cos )
λ = incoming photon wavelength
λ' = scattered photon wavelength
COMPTON WAVELENGTH
h
C =
m0c
Where m0 is the
mass of the
target particle

Example: Mr. Davis detonates an EMP weapon to
destroy some robots. The bomb releases gamma rays
with a wavelength of 3x10-11 m and the deflect with
nitrogen and oxygen electrons at an angle of 45
degrees. What is the wavelength of the scattered
gamma-rays?
Volunteer for:
Givens
Equation
 ' = c (1- cos )
  3x1011m
c  .00243x109 m
  45)
 '(3x1011 m)  .00243x109 m(1  cos45)
 '(3x10 m)  7.19x10
11
-13
 ' 3.07x10 m
-11
CLASSWORK
Two problems (9&10) require the use of photon
energy, from the photoelectric effect unit, we will
 If you finish these problems today I will come
around and give you extra credit.



Spend the rest of class working on your
classwork.
There is a bonus assignment if you finish early.
DO NOW (3/10/14)
X-rays of wavelength 0.456nm are
scattered from a block of carbon.
What will the Compton Shift be at:
a) 0˚
b) 15˚
c) 45˚
CLASSWORK
 At
the end of class there will be a one
problem Check for Understanding
that is related to your Do-Now.
 You

have all of class to ask questions.
Don’t forget you can use the Parking Lot.

I will put all necessary equations and
variables on the board.
CLASSWORK
Continue working on your classwork from
Friday.
 Questions 8,9, and 10 use energy which we
will learn tomorrow. Extra Credit if you
solve them today.



If you finish early there is a bonus and you
can start tomorrow’s classwork.
Check for Understanding last 10 minutes of
class.
CHECK FOR UNDERSTANDING (3/10/14)
X-rays of wavelength 0.789nm are
scattered from a block of carbon.
What is the angle of reflection of
the photon if the Compton Shift is:
a) 0.000326nm
b) 0.001215nm
c) 0.002430nm
DO NOW (3/11/14) ON YOUR NOTESHEET:
(5 MINUTES)
A 0.123-nm photon collides with a
stationary electron. After the collision, the
electron moves forward and the photon
recoils backwards. Do this on your notesheet but I’m going
to stamp your Do Now paper.
Draw a picture of the situation.
2) What is the angle between the scattered
photon and the electron?
3) List three things that you have learned
1)
GUIDED NOTESHEET
Looking
at the problem on
the notesheet, what are we
solving for?
 The
Kinetic Energy of the
Electron
GUIDED NOTESHEET
 Lets
start by looking at the motion of
Wherethe
does
the electron
electron:
get the energy to start
moving?
 When is the
electron moving:
Before the collision?
The
collision with the
 After Collision?

photon!
 The
electron starts out as Stationary
 After the collision it’s moving
CONSERVATION
 The
 Is
electron gains energy from it’s
collision with the photon.
that energy created from nothing?
Where does it come from?
 The
photon gives the electron some
energy.
INCIDENT PHOTON

has energy E and linear momentum p:
E
hc

E
p
c
SCATTERED PHOTON

has energy E :
hc
E
'
THE COMPTON EFFECT
 The
photon gives part of its energy to
one of the electrons, in the form of
KE
 Total energy and momentum must
be conserved.
LOSS IN PHOTON ENERGY =
GAIN IN ELECTRON ENERGY
KEelectron
= Eincident photon –
Escattered photon
Equivalent
notes sheet!
formulas are on your
EXAMPLE (5 MINUTES):
a) A 70-keV photon is Comptonscattered by an electron. What
is the wavelength of this initial
photon?
b) If the scattered photon comes
off at 27, what is its
wavelength after being
scattered?
BACK TO THE GUIDED NOTESHEET
 What
 The
variables do we have so far?
Initial wavelength of the photon
 The Angle between the photon and
electron
GUIDED PROBLEM

We are trying to solve for the energy of the
scattered electron, how does this relate the
energy lost by the photon?
are we solving
for?
LOSS What
IN PHOTON
ENERGY
=
GAIN IN ELECTRON ENERGY
GUIDED PROBLEM

We now need the energy of the scattered
photon, what equation do we want to use?
hc
Knowing that Photon Energy is
E

transferred to the electron, what
should we try to solve
 ' for now?


To solve for the energy, what variable do we
need to solve for?
 This means we need to solve for λ`
SOLUTION (5 MINUTES)

Givens:

Equation:

We need:

Solve for λ`
  .123nm
c  .00243nm
  180
 ' = c (1- cos )
 ` ______
Eelectron  ______
 ' = c (1- cos )  
 ' = .00243(1- cos(180)) .123 .1278nm

Electron Energy:
1240 1240
E

 393 eV
.123 .1278
PRACTICE:
use the rest of
class to work on your
classwork.
 It
 It
 Exit
is due on Friday.
Ticket at the end of class.
EXIT TICKET (3/11/14)
A 0.234-nm photon collides with a
stationary electron. After the collision,
the electron moves forward and the
photon recoils backwards.
Calculate the Kinetic Energy of the electron.
CONCEPTUAL QUESTIONS (3/12/14) (5 MINUTES)
In Compton Scattering
1) What happens to energy lost by the
incident photon?
2) The wavelength of the scattered
photon (increases/decreases) after
collision with the electron.
3) What is the equation for the energy of
a scattered electron?
DO NOW (3/12/14) (8 MINUTES)
1) What is the equation for the energy of a
scattered electron?
2) A 0.234-nm photon collides with a
stationary electron. After the collision, the
electron moves forward and the photon recoils
backwards.
a) Calculate the wavelength of the scattered photon.
b) Calculate the Kinetic Energy of the electron.
108 eV
GROUP QUIZ REVIEW
 I’m
going to check one paper per group.
 Competition
 First
for Quiz Extra Credit
Three groups to finish the
worksheet with every problem
correct get Extra Credit
GROUP QUIZ REVIEW
 When
you finish a page raise your
hand and I will come check it.
 If
you get stuck, skip that problem
and come back to it later.
PERIOD 4
Cortney
Stephanie
Ambe
Emilie
Maria
Rakem
Imani
Alexis
India H
Myeasher
Tyler
Briahna
Chalet
Ayona
Ayanna
Alex
Heaven
Jasir
Corey
Jasmine
India C
Shaitia
Emmeranda
Ciairah
Johnelle
PERIOD 6
Brianna
Brooke
Imani
Vaughn
Maria
Morgan
Uyen
Charles
Kate
Kendall
Teira
Shaolin
Tristan
Kayla
Tariq
Kareem
De’Aira
Shania
Chelsey
Justin
PERIOD 7
Denise
Ayana
Mariah
Sharae
Maullea
Jermira
Jaleel
Leez
Alvin
Ti-Taiyonna
Shamar
Chance
Daja
Will H
Ta’es
Kyallah
Katesha
Rubi
Courtnei
Will D
Tatiana
Malcolm
Michael
Shem
Leon
Camille
Stephanie
Quinones
GROUP QUIZ REVIEW
 When
you finish a page raise your
hand and I will come check it.
 If
you get stuck skip that problem and
come back to it later.
 I’m
going to check one paper per group,
so make sure one paper has all the
solutions.
COMPTON SHIFT:
The change in wavelength of
scattered photon
h
 ' =
(1- cos )
m0c
 '- = c (1- cos )
THE COMPTON EFFECT
Do
Now (3/13/12): Photons
are released with a
-11
wavelength of 4.7x10 m
and they deflect with
nitrogen and oxygen
electrons at an angle of 60
degrees. What is the
wavelength of the scattered
gamma-rays?
EXAMPLE:
A
70-keV photon is
Compton-scattered
by an electron. If the
scattered photon
comes off at 27, what
is its wavelength?
DO NOW (3/14/12):
A
60 keV photon is
Compton-scattered
by an electron. If the
scattered photon
comes off at 36, what
is its wavelength?
EXAMPLE:

A 210-nm photon collides with a stationary
electron. After the collision, the electron moves
forward and the photon recoils backwards.
Calculate the kinetic energy of the electron.
DO NOW (3/15/12):
A
0.23-nm photon collides
with a stationary electron.
After the collision, the
electron moves forward
and the photon recoils
backwards. Calculate the
kinetic energy of the
electron.
EXIT TICKET (3/10/14)
A
0.045-nm x-ray is scattered
through an angle of 30º. What is the
frequency of the scattered x-ray?
```