Reminder

1
Reminder!!

• Quiz 2 Today! Please sit in the DARK colored
  seats

2
Topics for Today

• Nuclear Fusion I
• Where do the neutrons come from?
• Lab next week! Neutron Activation of Silver
• Where do we get the neutrons?
• Poo-bee and Am-bee
• Quiz 2

3
Readings for Today

• For more on Neutron Sources, see Section 7.3

4
Topics for Monday

• Nuclear Fission II
• The BIG difference between U-235 and U-238
• Nuclear Fission
• Fission Products (Nuclear Waste and Fallout)
• What is a Breeder Reactor?

5
Readings for Monday

• What do neutron sources have to do with the
  atomic bomb? See Section 7.2
• Nuclear Waste. Section 7.9

What is a breeder reactor? Section 7.6
6
Announcements!
7
If you will be gone for a quiz or exam at any
point during the semester, please tell me and
your TA YESTERDAY!
8
PRELAB QUIZ for Week 3 Due BEFORE your lab this
week
You will have three attempts this week (and for
all the rest).
9
Lab next week

• Need an alternate lab because of a health
  concern?
• Talk with your TA.

10
QUIZ 2 Today. Non-memory calculators are allowed
11
Topics for Today

• Nuclear Fusion I
• Where do the neutrons come from?
• Lab next week! Neutron Activation of Silver
• Where do we get the neutrons?
• Poo-bee and Am-bee
• Quiz 2

12
How do people make new isotopes??
13

• Lab last week why do isotopes decay?

a
ß
14

• Lab last week why do isotopes decay?

a
Nucleus too heavy
ß
15

• Lab last week why do isotopes decay?

a
Nucleus too heavy
ß
Too many neutrons
16

• Lab last week when do they decay?

How do people make new isotopes??
a
Nucleus too heavy
ß
Too many neutrons
17

• Lab last week when do they decay?

How do people make new isotopes??
How about adding particles to the nucleus?
a
Nucleus too heavy
ß
Too many neutrons
18

Particle
Stable Isotope
Radioactive Isotope
19

Particle
Stable Isotope
Radioactive Isotope
What kind of particle should we add?
20
Next Week Lab!

• Ag n Ag

107 47
108 47
1 0
21
Next Week Lab!

• Ag n Ag

107 47
108 47
1 0
Where do we find a neutron?
22

• 2 neutron sources
• Am-Be (am-bee)
• Pu-Be (poo-bee)

23

• 2 neutron sources
• Am-Be (am-bee)
• Pu-Be (poo-bee)

americium beryllium source
plutonium beryllium source
24

• 2 neutron sources
• Am-Be (am-bee)
• Pu-Be (poo-bee)

americium beryllium source
plutonium beryllium source
Both Am and Pu are alpha emitters. So, neutron
sources work the same way.
25
We will use an Am-Be source in lab next week!
26
We will use an Am-Be source in lab next week!
How does is work?
27
Quick Recipe for Making Neutrons

• a source
• Target
• Something to slow down the neutrons!

28
Quick Recipe for Making Neutrons

• a source
• Target
• Something to slow down the neutrons!

29
Alpha Source
Am Np
?
4 2
0 0
241 95
237 93
a
30
Alpha Source
Am Np
?
4 2
0 0
241 95
237 93
a
Where else have we seen americium?
31
(No Transcript)
32
Quick Recipe for Making Neutrons

• a source
• Target
• Something to slow down the neutrons!

33

• Target The unfortunate atom that gets hit with
  the alpha particle. In our case, Beryllium (Be).

34


Beryllium-9 Alpha
Particle
Carbon-12 neutron
TARGET
New Nucleus
35
OR

• Be 42He 126C 10n 00

9 4
?
36
OR

• Be 42He 126C 10n 00

9 4
?
EXTREMELY High Speed Neutron!
37
Remeber Our Goal

• Ag n Ag

107 47
108 47
1 0
38
It will NOT be absorbed by silver

• Be 42He 126C 10n 00

9 4
?
EXTREMELY High Speed Neutron!
39
(No Transcript)
40
(No Transcript)
41
Can we slow down the neutrons?
42
OR

• Be 42He 126C 10n 00

9 4
?
How can we slow it down?
EXTREMELY High Speed Neutron!
43
Quick Recipe for Making Neutrons

• a source
• Target
• Something to slow down the neutrons!

44

• Slow them with paraffin

What is paraffin?
45
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C-H
H-C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Paraffin is a hydrocarbon
46
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C
-C-H
H-C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
More than 20 carbon atoms in a row
Very good at slowing down neutrons!
Paraffin is a hydrocarbon
47

• Slow them with paraffin

What is paraffin?
Where do we find paraffin?
48

• Paraffin is a wax
• Can be used for candles

49
Producing Neutrons
Am
Np
?
C
Be
Paraffin
n
50

• Using the neutron..

51
Next Weeks Lab!

• Ag n Ag

107 47
108 47
1 0
52
Next Weeks Lab!

• Ag n Ag

107 47
108 47
1 0
How does this radiate?
53

• This was one example

54
Irene Curie won the Nobel Prize in 1935 for the
discovery of artificial radioactivity.
55

• Using processes similar to AmBe and PuBe, they
  were able to create isotopes that never, before,
  existed.

56

• Using processes similar to AmBe and PuBe, they
  were able to create isotopes that never, before,
  existed.

Lets try one!
57
Remember!!
Alpha Particle
NEW Element
Neutron


Target
58
Example 1

• 105B 42He

59
Example 1
Remember to balance to mass number and protons!

• 105B 42He 137N 10n

60
Your Turn

• What if Mg-24 is the target?

61
Remember!!
Alpha Particle
NEW Element
Neutron


Target
62
Your Turn

• Magnesium-24 is bombarded with an alpha particle
  to produce an isotope of silicon and a neutron.

2412Mg 42He 2714Si 10n