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The Development of a Compact Pyroelectric X-Ray Generator
Ross McCart
Nuclear DepartmentHMS Sultan
Project Aims
• Build a Pryoelectric X-Ray Source.
• Test and characterise the source. (Modify design if necessary)
• Research into increasing energy of X-Rays
• Possibly couple source with X-Ray collimator.
• (Adapt the source to enable the production of Neutrons)
Pyroelectric Materials
• Non-conducting crystals develop an electric polarisation when they are subjected to a uniform temperature change.
• Only in crystals with a Polar axis.
• The requirements are fulfilled in about 10 out of the 32 crystal classes.
• Effect known since 314 B.C
• Pyroelectric effect found in motion detection, pollution monitors and in bones.
• Tourmaline, Sugar cane, Lithium Tantalate and Barium Niobate
Properties of Lithium Tantalate
Ferroelectric Effect – Polarising the crystal
LiTaO3
Z+
Z-
+
--
Crystal
LiTaO3
Z-
Li+
OO O
Ta+
Li+
OO O
Ta+
Properties of the Crystal
QACT dt
dTAI CC
For a 100°C change over 180 seconds an emission current of 2x10-8Amps is
predicted.
6.25x1010 electrons per second
The rate of polarisation per change in temperature. Negative as polarisation
occurs when crystal cools.
-2.3x10-4Cm-2K-1 for LiTaO3
Pyroelectric Constant Emission Current
Potential Difference
Cg CC
+ - +
Cg CC
G
G
C
CC
C
d
A
d
A
TA
C
QV
0
X Ray Production
Source Amptek
Cooling CycleHeating Cycle
Setup
Advantages and Disadvantages
• Low power, approximately 1.4mW.
• Runs on a 12V battery or power supply.
• Handheld and portable.
• No Radioactive Sources.
• Solid State – no moving parts
• X-Ray Flux approximately 108 Photons per second
• Isotropic production of X-Rays
• Not a continuous flux
• Cannot be turned off instantaneously
• Limited end point energy with one crystal setup.
Potential Uses
• Security
• X-Ray fluorescence
• Radiography
• Teaching and Research
• Bomb Disposal
• Non-destructive testing
Wikipedia
Neutron Generation
2H 2 H 4He 3He01n 2.45MeV
2H 2 H 4He 3H11p
2H 3 H 4He01n 14.10MeV
The potential barrier of deuterium is 288keV, however the deuterium ions are able to tunnel under the barrier, lowering the energy required.
Goals
Short Term
• Complete Build
• Characterise the electric field from X Ray emission
Research Areas of Interest
• Two Crystal Setup – Increasing Tube Potential
• Stacking Crystals – Increasing Crystal Thickness
• Continuous Flux Using Multiple Crystals
Acknowledgments
• Dr Ian Giles
• Dr Kirk D Atkinson
• Miss Samantha Morris
• Sean Jarmen
• And other members of staff at the Nuclear Department.
Any Questions?