Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session NJ: Mini-symposium in Applications of Nuclear Physics IMini-Symposium
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Chair: Monika Stachura, TRIUMF Room: Junior Ballroom A |
Sunday, October 16, 2016 8:30AM - 9:06AM |
NJ.00001: Development of Radioisotope Micropower Sources. Invited Speaker: J David Robertson Microelectromechanical systems (MEMS) are considered to be one of the discriminating technologies of the 21st century. In order to take full advantage of the MEMS revolution, the power sources for these electromechanical systems must follow a similar trend of increased functionality at decreased size. Because of their high energy density, radioactive micropower sources are an alternative to next generation battery and fuel cell technologies for applications where volume is at a premium. This presentation will focus on our development of liquid-semiconductor nuclear batteries as compact power supplies for MEMS. [Preview Abstract] |
Sunday, October 16, 2016 9:06AM - 9:18AM |
NJ.00002: Distinguishing magnetic vs. quadrupolar relaxation in b-NMR using 8Li and 9Li A. Chatzichristos, R.M.L. McFadden, V.L. Karner, D.L. Cortie, A. Fang, C.D.P. Levy, W.A. MacFarlane, G.D. Morris, M.R. Pearson, Z. Salman, R.F. Kiefl Beta-detected NMR is a powerful technique in condensed matter physics.It uses the parity violation of beta decay to detect the NMR signal from a beam of highly polarized radionuclides implanted in a sample material.Spin-lattice relaxation (SLR) is studied by monitoring the rate with which the asymmetry between the beta counts in two opposing detectors is lost.Unlike classical NMR,b-NMR can study thin films and near-surface effects.The most common b-NMR isotope at TRIUMF is 8Li,which has a quadrupole moment,thus it is sensitive to both magnetic fields and electric field gradients.A challenge with 8Li b-NMR is identifying the predominant mechanism of SLR in a given sample.It is possible to distinguish between SLR mechanisms by varying the probe isotope.For two isotopes with different nuclear moments,the ratio of SLR rates should be different in the limits of either pure magnetic or quadrupolar relaxation.This method has been used in classical NMR and we report its first application to b-NMR.We measured the SLR rates for 8Li and 9Li in Pt foil and SrTiO3.Pt is a test case for pure magnetic relaxation.SrTiO3 is a non-magnetic insulator,but the source of its relaxation is not well understood.Here we show that its relaxation is mainly quadrupolar. [Preview Abstract] |
Sunday, October 16, 2016 9:18AM - 9:30AM |
NJ.00003: BetaNMR Experiments on Liquid Samples A. Gottberg, M. Stachura, L. Hemmingsen, W.A. MacFarlane In 2012 betaNMR spectroscopy was successfully applied on liquid samples; an achievement which opens new opportunities in the fields of chemistry and biochemistry. This project was motivated by the need for finding a new experimental approach to directly study biologically highly relevant metal ions, such as Mg(II), Cu(I), Ca(II), and Zn(II), which are silent in most spectroscopic techniques. The resonance spectrum recorded for Mg-31 implanted into an ionic liquid sample showed two resonances which originate from Mg ions occupying two different coordination geometries, illustrating that this technique can discriminate between different structures. This proof-of-principle result lays the foundation for studies of these metal ions at low concentrations and in environments of biological relevance where other methods are silent. The prototype chamber for bio-betaNMR allows for experiments not only on different samples such as: liquids, gels and solids, but also operates at different vacuum environments. In order to exploit the potential of betaNMR on liquid samples, tests with polarized beams of Mg-29 and Mg-31 have recently been performed at the ISAC facility at TRIUMF. [Preview Abstract] |
Sunday, October 16, 2016 9:30AM - 9:42AM |
NJ.00004: ABSTRACT WITHDRAWN |
Sunday, October 16, 2016 9:42AM - 9:54AM |
NJ.00005: Climate Change Effects on Iron Availability to Arctic Phytoplankton Maria Teresa Maldonado, Jingxuan Li, David Semeniuk, Nina Schuback, Clara Hoppe Phytoplankton, unicellular algae, are responsible for 50{\%} of earth's photosynthesis, and for a significant consumption of atmospheric CO$_{\mathrm{2}}$. Iron (Fe) is essential for phytoplankton, but is extremely depleted in seawater, limiting photosynthesis in 30{\%} of the global ocean. Oceanic Fe bioavailability is determined by physical and chemical processes. The Arctic Ocean is experiencing the greatest decrease in seawater pH (termed ocean acidification). Simultaneously, ice retreat is promoting higher light intensity in Arctic Ocean. We investigated the effects of ocean acidification and high light on Fe availability to Arctic phytoplankton. Iron uptake rates by plankton, using the radionuclide $^{\mathrm{55}}$Fe, were used as a proxy for Fe bioavailability. In an Arctic summer research cruise, we measured Fe uptake by two phytoplankton populations subjected to two light levels, as well as present CO$_{\mathrm{2}}$ levels (400ppm) or those expected by 2100 (1100 ppm). Our results demonstrated that high CO$_{\mathrm{2}}$ decreases Fe availability, while high light increases it, suggesting that future Fe bioavailability might be similar to present day. However, the detrimental effects of high CO$_{\mathrm{2}}$ were more pronounced in the plankton population exposed to higher seawater temperature. Future studies should investigate the interaction among light, CO$_{\mathrm{2}}$ and temperature on the Fe physiology of Arctic phytoplankton. [Preview Abstract] |
Sunday, October 16, 2016 9:54AM - 10:06AM |
NJ.00006: Application of nuclear physics in medical physics and nuclear medicine Cornelia Hoehr Nuclear physics has a long history of influencing and advancing medical fields. At TRIUMF we use the applications of nuclear physics to diagnose several diseases via medical isotopes and treat cancer by using proton beams. The Life Science division has a long history of producing Positron Emission Tomography (PET) isotopes but we are also investigating the production of SPECT and PET isotopes with a potential shortage for clinical operation or otherwise limited access to chemists, biologists and medical researchers. New targets are being developed, aided by a simulation platform investigating the processes inside a target under proton irradiation -- nuclear, thermodynamic, and chemical. Simulations also aid in the development of new beam-shaping devices for TRIUMF's Proton Therapy facility, Canada's only proton therapy facility, as well as new treatment testing systems. Both promise improved treatment delivery for cancer patients. [Preview Abstract] |
Sunday, October 16, 2016 10:06AM - 10:18AM |
NJ.00007: Nuclear emission-based imaging in the study of brain function Ivan Klyuzhin, Vesna Sossi Nuclear emission - based imaging has been used in medicine for decades either in the form of Single Photon Emission Computerized Tomography (SPECT) or Positron Emission Tomography (PET). Both techniques are based on radiolabelling molecules of biological interest (radiotracers) with either a gamma (SPECT) or a positron (PET) emitting radionuclide. By detecting radiation from the radiolabels and reconstructing the acquired data it is possible to form an image of the radiotracer distribution in the body and thus obtain information on the biological process that the radiotracer is tagging. While most of the clinical applications of PET are in oncology, where the glucose analogue $^{\mathrm{18}}$F-flurodeoxyglocose (FDG) is the most commonly used radiotracer, the importance of PET imaging for brain applications is rapidly increasing. Numerous radiotracers exist that can tag different neurotransmitter systems as well as abnormal protein aggregations that are known to underlie several brain diseases: amyloid deposition, a characteristic of Alzheimer's, and, more recently, tau deposition, which is deemed abnormal not only in dementia, but also in Parkinson's syndrome and traumatic brain injury. Imaging has shown that may brain diseases start decades before clinical symptoms, in part explaining the difficulty of developing adequate treatments. This talk will briefly summarize the role of PET imaging in the study of neurodegeneration and discuss the upcoming hybrid PET/MRI imaging instrumentation. [Preview Abstract] |
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