Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session I2: Applications of Nuclear Science |
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Sponsoring Units: DNP Chair: Alexander Saunders, Los Alamos National Laboratory Room: Hyatt Regency Dallas Landmark B |
Sunday, April 23, 2006 10:30AM - 11:06AM |
I2.00001: Laser spectroscopic determination of the $^{6}$He nuclear charge radius Invited Speaker: The weakly bound $^{6}$He nucleus is an excellent testing ground for few-body nuclear calculations and is of great interest since its halo structure was suggested in the 80s. In this thesis work, we performed precision laser spectroscopy on individual metastable $^{6}$He atoms confined and cooled in a magneto-optical trap (MOT). This technique enabled us to accurately measure the isotope shift between $^{6}$He and $^{4}$He to be 43194.772(56) MHz in the 2$^{3}$S$_{1}$--3$^{3}$P$_{2}$ transition at 389 nm. Based on this measurement and the atomic theory calculation, the root-mean-square charge radius of $^{6}$He was determined to be 2.054(14) fm [1]. This result confirmed the neutron-halo structure of the $^{6}$He nucleus model-independently for the first time and helps reveal the structure of the loosely bound system. This experiment also demonstrates a new technique for precision laser spectroscopy of short-lived radioactive atoms, and provides a unique atomic method for nuclear physics studies. [1] L.-B. Wang \textit{et al}., Phys. Rev. Lett. \textbf{93}, 142501 (2004) [Preview Abstract] |
Sunday, April 23, 2006 11:06AM - 11:42AM |
I2.00002: The Task of Detecting Illicit Nuclear Material: Status and Challenges Invited Speaker: In August 1994, police at the Munich airport intercepted a suitcase from Moscow with half a kilogram of nuclear-reactor fuel, of which 363 grams was weapons- grade plutonium. A few months later police seized 2.7 kilograms of highly enriched uranium from a former worker at a Russian nuclear institute and his accomplices in Prague. These are just two of 18 incidents involving the smuggling of weapons grade nuclear materials between 1993 and 2004 reported by the International Atomic Energy Agency. The consequences of a stolen or improvised nuclear device being exploded in a U.S. city would be world changing. The concern over the possibility of a nuclear weapon, or the material for a weapon or a radiological dispersion device, being smuggled across U.S. borders has led to the deployment of radiation detection equipment at the borders. Related efforts are occurring around the world. Radiation portal monitors are used as the main screening tool, supplemented by handheld detectors, personal radiation detectors, and x-ray imaging systems. Passive detection techniques combined with imaging, and possibly active techniques, are the current available tools for screening cargo for items of concern. There are a number of physics limitations to what is possible with each technology given the presence of naturally occurring radioactive materials, commercial sources, and medical radionuclides in the stream of commerce. There have been a number of lessons learned to date from the various efforts in the U.S. and internationally about the capability for interdicting illicit nuclear material. [Preview Abstract] |
Sunday, April 23, 2006 11:42AM - 12:18PM |
I2.00003: High Performance Organ-Specific Nuclear Medicine Imagers. Invited Speaker: One of the exciting applications of nuclear science is nuclear medicine. Well-known diagnostic imaging tools such as PET and SPECT (as well as MRI) were developed as spin-offs of basic scientific research in atomic and nuclear physics. Development of modern instrumentation for applications in particle physics experiments offers an opportunity to contribute to development of improved nuclear medicine (gamma and positron) imagers, complementing the present set of standard imaging tools (PET, SPECT, MRI, ultrasound, fMRI, MEG, etc). Several examples of new high performance imagers developed in national laboratories in collaboration with academia will be given to demonstrate this spin-off activity. These imagers are designed to specifically image organs such as breast, heart, head (brain), or prostate. The remaining and potentially most important challenging application field for dedicated nuclear medicine imagers is to assist with cancer radiation treatments. Better control of radiation dose delivery requires development of new compact in-situ imagers becoming integral parts of the radiation delivery systems using either external beams or based on radiation delivery by inserting or injecting radioactive sources (gamma, beta or alpha emitters) into tumors. [Preview Abstract] |
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