The Development of a Compact Pyroelectric X-Ray Generator Ross McCart HMS Sultan Nuclear Department 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) X-Ray Tube 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 Z+ + LiTaO3 -Z- Crystal + Ta Z- O O O + LiTaO3 Li Properties of the Crystal Pyroelectric Constant Q AC T Emission Current I C AC dT dt The rate of polarisation per change in temperature. Negative as polarisation occurs when crystal cools. For a 100°C change over 180 seconds an emission current of 2x10-8Amps is predicted. -2.3x10-4Cm-2K-1 for LiTaO3 6.25x1010 electrons per second Potential Difference + V Q C A C - T+ AC AG 0 C dC dG C C g C Cg CC X Ray Production Heating Cycle Cooling Cycle Source Amptek 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 2 2 4 3 1 H H He He 0 n 2 2 4 3 2.45MeV 1 H H He H 1 p 2 3 4 1 H H He 0 n 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?