Gamma rays are high-energy electromagnetic radiation emissions. They can penetrate materials like air and human tissue, more readily than x-rays, making them an ideal tool for examining the body's organs. A gamma camera is used to detect gamma emissions after a patient has been injected with a radioactive tracer. During the decay of the tracer, gamma rays are emitted. The camera detects the emitted gamma rays, and the position in the body from which gamma rays are emitted is recorded. Thus, an image of the distribution of the tracer in the body is obtained.
Neutrons are produced in fission decay of elements like 240Pu and 238U and can also be generated by bombarding heavy nuclei like Mercury with high energy protons. Once produced such neutrons are extremely penetrating and can travel through dense and thick materials like concrete, lead, or steel.
However, special materials can be used to stop and convert neutrons into ionizing radiation, which can be readily detected. The most common materials used are 3He and 10B. These materials possess an extremely high stopping power for thermal neutrons. By using these materials in various forms, detectors can determine time and position accurately and efficiently.
SBIR is an acronym for Small Business Innovative Research. It is a federal program funding small businesses to develop new technology.