1. Leybold X-Ray Experiment
Hannah Currivan| Supervisor: Elizabeth Gregan, Fran Pedreschi, Timothy Hogan| Dublin Institute of Technology
Introduction
X-Rays are electromagnetic waves of high
energy and very short wavelength, which are
able to pass through many materials opaque
to light [1].
The Leybold X-Ray apparatus is a machine
which is used to carry out atomic and nuclear
physics experiments in the lab.
Aims
Develop a set of experiments using the Leybold
Didactic X‐ray System owned by the School of
Physics.
Theory
Bragg Law:
Gives the angles for coherent and
incoherent scattering from a crystal lattice.
When X-rays are incident on an atom, they
make the electronic cloud as does
any electromagnetic wave [2].
Compton Scattering:
An inelastic scattering of a photon by a free
charged particle, usually an electron.
It results in a decrease in energy
of the photon ,called the Compton effect.
Attenuation:
The attenuation of X-rays is the decrease in
intensity due to matter and is caused primarily
by two effects: Scattering and absorption.
When the X-ray photons encounter the material
they can be scattered in different directions,
thereby reducing the intensity in the original
direction.
This may be elastic or inelastic in nature.
When the photons’ energy is completed
transferred to the atoms of the attenuator it is
called absorption.
Planck's Constant:
This relates the energy in one quantum of
electromagnetic radiation to the frequency of
that radiation. Value: 6.626176 x 10-34 joule-
seconds.
Materials
Procedure
Step 1
Place the crystal
into the Leybold X-
Ray, distance
between the centre
of the crystal to the
Collimator, eg.
5cm.
Step 2
GM tube is
connected to the
correct port and
adjust the arm of
the sensor holder
so that the sensor
opening is roughly
6 cm from the
centre of the crystal.
Close the doors and
switch on the
apparatus.
Step 3
Open the “X-Ray
Apparatus”
program on the
Labs PC. Click on
the “settings”
button and select
“crystal
Calibration”.
Select NaCl and
Mo in the two
drop 24 Neal
drop.
Step 4
Results • For the attenuation senior lab there are missing
parts to the experiment such as the Absorption
Accessories to the Leybold X-Ray Apparatus.
• Further work will be needed on how the Leybold
X-Ray Apparatus software works out the
calibration, as it asks for which crystal you may
be examining , that being NaCl (Sodium
Chloride) or LiF (Lithium Fluoride).
• For the Compton Effect it is to be noted that the
R value is read off the Leybold X-Ray Machine
and not the computer software .
Further Work
Conclusion
• As you increase the voltage or current the
higher the intensity of the transmission.
• By changing the calibration settings for each
crystal to a different one, the realisation that this
affects the results by changing the angle at
which the diffraction happens for each crystal.
• By changing the Filament from Molybdenum to
Tungsten, from which the X-Rays come from, it
changes the clarity at which the peaks are
appearing.
• A new senior laboratory based on Planck’s
constant.
• Overall the aim was achieved to make a new
senior laboratory experiment, with some
interesting findings along the way.
•Leybold X-Ray Machine
•NaCl (Sodium Chloride) Crystal
•LiF (Lithium Fluoride) Crystal
•Detector
•Collimator
•X-Ray Program Software
Can’t handle the
crystal. The x-ray
apparatus will not
switch on unless
the door to the
chamber is closed
properly, the
display will flash to
indicate this.
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97 100 103 106 109 112 115 118 121 124
0
100
200
300
400
500
600
700
800
Wavelength
Transmission
Transmission Vs. Wavelength
LiF (20.0KV) LiF (25.0KV) LiF (30.0KV) LiF (35.0KV)
Fig 1. Change in Voltage of LiF , Transmission
Intensity Vs. Angle
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97 100 103 106 109 112 115 118 121 124
0
100
200
300
400
500
600
700
Angle
Transmissions
Transmissions Vs. Wavelength
LiF (0.2mA) LiF (0.4mA) LiF (0.6mA) LiF (0.8mA) LiF (1.00mA)
Fig 2. Change in Current of LiF, Transmission
(Intensity) Vs. Angle
Compton Effect:
min
pm
0
10
20
30
40
50
1/U / 1/kV
0 0.01 0.02 0.03 0.04
Fig 3. Planck’s Constant reading
The Planck’s constant that was achieved
here was a value of
6.64 x 10-34 joule-seconds.
Planck’s Constant :
Change in Voltage
Change in Current
Reference
[1] – Definition of X-Ray
https://www.google.ie/?gws_rd=cr,ssl&ei=kbwTV-
2vHYKrsgGWlqLQAg#q=definition+of+x-ray
[2]- Definition of Bragg’s Law
https://en.wikipedia.org/wiki/Bragg%27s_law
[3] – Leybold X-Ray Image
http://www.leybold-shop.de/physik/versuche-sek-ii-
universitaet/atom-und-kernphysik.html
Table 1. Count rate R0 for X-Ray
scattering at an Aluminum body.
Bragg’s Law