Improved technology for originating CEBAF's electron beam enables nuclear physics experimenters to gather better data more efficiently. CEBAF's injector originates the electron beam, establishes its special characteristics, and then injects it into the accelerator. Over time, as CEBAF experiments generate new knowledge, nuclear physics researchers need to interrogate nature itself ever more deeply — which means they need increasingly exacting characteristics in the beam. That makes injector advances important.
Dedicated positron emission mammography (PEM) systems potentially provide a high sensitivity, high resolution alternative to whole body PET for positron breast imaging. In collaboration with Duke University Medical Center (Tim Turkington, PI), we have designed, built and evaluated a large field of view (15 cm x 20 cm) PEM system. The device is built with a set of two pixellated LGSO/LYSO crystal scintillators coupled to arrays of compact position sensitive photomultiplier tubes.
The Q2 dependence of the charge form factor of the neutron, GEn, can provide vital information on the origin of charge distribution in the neutron. A precise determination of GEn has challenged physicists for more than 40 years, primarily from the lack of a free neutron target and the fact that the charge form factor is so small.
Researchers demonstrate a new technique for producing polarized positrons that could improve manufacturing and lead to new discoveries.
The Science
When an energetic electron beam strikes matter, it produces photons, or packets of light, that can further convert their energy into pairs of an electron and a positron, the anti-particle twin to the electron. Researchers demonstrated that if the original electron beam is polarized (electrons “spin” in one direction), this polarization can be transferred to the positrons with nearly 100 percent efficiency.
Calculations of a subatomic particle called the sigma provide insight into the communication between subatomic particles deep inside the heart of matter.
The Science
After decades of catching brief glimpses of a fleeting subatomic particle called the sigma in experimental data, nuclear physicists have used supercomputers to calculate it, with the result displaying similar properties to that of a real-world sigma particle inferred from experimental data.
A potentially cost-saving and performance-enhancing new approach to fabricating superconducting radiofrequency (SRF) accelerating cavities has been demonstrated by the Institute for Superconducting Radiofrequency Science & Technology (ISRFST) at Jefferson Lab. Several single-cell niobium cavities were made from material sliced from large-grain niobium ingots, rather than fine-grain material melted from ingots and formed into sheets by the traditional process of forging, annealing, rolling and chemical etching. In tests carried out by ISRFST, these cavities performed extremely well.
Optical fluorescence and radiopharmaceutical imaging offer complementary ways of studying small animal physiology. A small, high resolution compact gamma camera has been developed and built at Jefferson Lab and integrated into a dual modality SPECT/optical small animal imaging system at the German Cancer Research Center (Heidelberg, Germany; Joerg Peter, PI). The key design features of the 10cm x 10cm field of view gamma camera are the use of a 2 x 2 array of flat panel position-sensitive photomultiplier tubes and a pixellated scintillation crystal array.
Silicon is perhaps one of the most important materials in our technological world, but its performance is always ultimately limited by impurities. Mitigation by impurity elimination is not possible, and theoretical understanding is very limited. Thus, these experiments, in which real-time dynamical evolution of excited impurity dynamics is measured, are of high fundamental as well as technological importance.
