This award will support the development of a highly sensitive passive imaging detector of nuclear and radiological materials using liquid Xe to build and test a Compton gamma-ray imager. Liquid Xe is readily available, relatively cheap, large gamma-ray detection efficiency, and excellent energy and spatial resolution. Gamma-ray detectors with good energy resolution and imaging capabilities offer the highest attainable performance for locating interesting sources at long range; these include the use of HEU for 1001 keV and 2614 keV.
The proposed activities also include the training of postdocs, graduate and undergraduate students in detector simulation, design, fabrication, and characterization. The PIs plan to work with students at public schools, including students in high school, middle school, and first to six grade schools. The development of a two-phase Compton imager is expected to improve the position and energy resolution of gamma cameras used in liquid xenon PET (LXePET), which will result in better localization of the emitting malignant cells.
This work is the result of the first year of an Academic Research Instrumentation grant, administered by the National Science Foundation and being passed on to the Department of Homeland Security for the following 4 years. The subject of this work is the imaging of gamma rays using liquid xenon. This material has many advantages, including good energy resolution, sub-mm position resolution, and scalability to large active masses, which in turn results in very high gamma ray detection and imaging efficiency. This work is aided by the existing liquid xenon detetcor at Yale University, dubbed PIXeY, for Particle Identification in Xenon at Yale. In the first year of this grant we have tested the cryogenic systems of PIXeY, produced wire grids for generating uniform and tightly controlled electric fields, tested photomultipliers for reading out the scintillation signal, developed preamplifiiers for reading the charge signal with ~mm scale position resolution, and performed Monte Carlo simulations for optimizing the geometry for gamma ray imaging. We are now in a good position to test the uniformity of this new optimized system, and are aiming to set new records for energy resolution in a liquid xenon detector. Given the other advantages of liquid xenon (scalability and position resolution) we will be in a good position to demonstate stunning gamma images, with excellent angle and energy resolution.
