TRIUMF Laboratory Particle and Nuclear Physics | Date: 2015-04-24
A target system for irradiation of molybdenum with charged particles from an accelerator to produce technetium and molybdenum radioisotopes. The target system comprises a molybdenum-100 material brazed with a brazing alloy to a backing material. The backing material preferably comprises a dispersion-strengthened copper composite. The brazing alloy comprises copper and phosphorus.
Cipollone A.,University of Surrey |
Barbieri C.,University of Surrey |
Navratil P.,TRIUMF Laboratory Particle and Nuclear Physics
Physical Review Letters | Year: 2013
We extend the formalism of self-consistent Green's function theory to include three-body interactions and apply it to isotopic chains around oxygen for the first time. The third-order algebraic diagrammatic construction equations for two-body Hamiltonians can be exploited upon defining system-dependent one- and two-body interactions coming from the three-body force, and, correspondingly, dropping interaction-reducible diagrams. The Koltun sum rule for the total binding energy acquires a correction due to the added three-body interaction. This formalism is then applied to study chiral two- and three-nucleon forces evolved to low momentum cutoffs. The binding energies of nitrogen, oxygen, and fluorine isotopes are reproduced with good accuracy and demonstrate the predictive power of this approach. Leading order three-nucleon forces consistently bring results close to the experiment for all neutron rich isotopes considered and reproduce the correct driplines for oxygen and nitrogen. The formalism introduced also allows us to calculate form factors for nucleon transfer on doubly magic systems. © 2013 American Physical Society.
Sharma R.,TRIUMF Laboratory Particle and Nuclear Physics |
Vitev I.,Los Alamos National Laboratory
Physical Review C - Nuclear Physics | Year: 2013
We calculate the yields of quarkonia in heavy ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) as a function of their transverse momentum. Based upon nonrelativistic quantum chromodynamics, our results include both color-singlet and color-octet contributions and feed-down effects from excited states. In reactions with ultrarelativistic nuclei, we focus on the consistent implementation of dynamically calculated nuclear matter effects, such as coherent power corrections, cold nuclear matter energy loss, and the Cronin effect in the initial state. In the final state, we consider radiative energy loss for the color-octet state and collisional dissociation of quarkonia as they traverse through the QGP. Theoretical results are presented for J/ψ and Υ and compared to experimental data where applicable. At RHIC, a good description of the high-pT J/ψ modification observed in central Cu+Cu and Au+Au collisions can be achieved within the model uncertainties. We find that measurements of J/ψ yields in proton-nucleus reactions are needed to constrain the magnitude of cold nuclear matter effects. At the LHC, a good description of the experimental data can be achieved only in midcentral and peripheral Pb+Pb collisions. The large fivefold suppression of prompt J/ψ in the most central nuclear reactions may indicate for the first time possible thermal effects at the level of the quarkonium wave function at large transverse momenta. © 2013 American Physical Society.
Kumar A.,TRIUMF Laboratory Particle and Nuclear Physics |
Tulin S.,University of Michigan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
We propose a simple model where dark matter (DM) carries top flavor and couples to the Standard Model through the top quark within a framework of minimal flavor violation. Top-flavored DM can explain the anomalous top forward-backward asymmetry observed at the Tevatron, while remaining consistent with other top observables at colliders. By virtue of its large coupling to the top, DM acquires a sizable loop coupling to the Z boson, and the relic density is set by annihilation through the Z. We also discuss constraints from current direct detection searches, emphasizing the role of spin-dependent searches to probe this scenario. © 2013 American Physical Society.
Price E.W.,University of British Columbia |
Price E.W.,TRIUMF Laboratory Particle and Nuclear Physics |
Orvig C.,University of British Columbia
Chemical Society Reviews | Year: 2014
Radiometals comprise many useful radioactive isotopes of various metallic elements. When properly harnessed, these have valuable emission properties that can be used for diagnostic imaging techniques, such as single photon emission computed tomography (SPECT, e.g.67Ga, 99mTc, 111In, 177Lu) and positron emission tomography (PET, e.g.68Ga, 64Cu, 44Sc, 86Y, 89Zr), as well as therapeutic applications (e.g.47Sc, 114mIn, 177Lu, 90Y, 212/213Bi, 212Pb, 225Ac, 186/188Re). A fundamental critical component of a radiometal-based radiopharmaceutical is the chelator, the ligand system that binds the radiometal ion in a tight stable coordination complex so that it can be properly directed to a desirable molecular target in vivo. This article is a guide for selecting the optimal match between chelator and radiometal for use in these systems. The article briefly introduces a selection of relevant and high impact radiometals, and their potential utility to the fields of radiochemistry, nuclear medicine, and molecular imaging. A description of radiometal-based radiopharmaceuticals is provided, and several key design considerations are discussed. The experimental methods by which chelators are assessed for their suitability with a variety of radiometal ions is explained, and a large selection of the most common and most promising chelators are evaluated and discussed for their potential use with a variety of radiometals. Comprehensive tables have been assembled to provide a convenient and accessible overview of the field of radiometal chelating agents. © 2014 The Royal Society of Chemistry.
Salas P.F.,University of British Columbia |
Herrmann C.,University of British Columbia |
Herrmann C.,TRIUMF Laboratory Particle and Nuclear Physics |
Orvig C.,University of British Columbia
Chemical Reviews | Year: 2013
Malaria is a worldwide neglected infectious disease that, despite decades of research invested in its prevention and treatment, remains one of the main causes of mortality and morbidity in the world. As reported by the World Health Organization (WHO) in 2011, 3.3 billion people were at risk of malaria, mainly in the 106 malaria-endemic countries located in the tropical and subtropical zones of the globe. Malaria is preventable through methods of malaria vector control. The two most important vector control methods recommended by the WHO are long-lasting insecticide-treated mosquito nets (LLIN) and indoor residual spraying (IRS). Indoor residual spraying (IRS) with WHO-approved chemicals consists of application of residual insecticides to the inner surfaces of dwellings. Of all factors that have contributed to the recrudescence of malaria in the last 50 years, increasing antimalarial drug resistance is probably the major contributor. This phenomenon, which rapidly depleted the therapies available to fight malaria, has led to intensive research carried out for decades that produced a large pool of antimalarial drugs.
Navratil P.,TRIUMF Laboratory Particle and Nuclear Physics |
Navratil P.,Lawrence Livermore National Laboratory |
Quaglioni S.,Lawrence Livermore National Laboratory
Physical Review Letters | Year: 2012
We apply the ab initio no-core shell model combined with the resonating-group method approach to calculate the cross sections of the H3(d,n)He4 and He3(d,p)He4 fusion reactions. These are important reactions for the big bang nucleosynthesis and the future of energy generation on Earth. Starting from a selected similarity-transformed chiral nucleon-nucleon interaction that accurately describes two-nucleon data, we performed many-body calculations that predict the S factor of both reactions. Virtual three-body breakup effects are obtained by including excited pseudostates of the deuteron in the calculation. Our results are in satisfactory agreement with experimental data and pave the way for microscopic investigations of polarization and electron-screening effects, of the H3(d,γn)He4 bremsstrahlung and other reactions relevant to fusion research. © 2012 American Physical Society.
Morris G.D.,TRIUMF Laboratory Particle and Nuclear Physics
Hyperfine Interactions | Year: 2014
The β-NMR facility at ISAC is constructed specifically for experiments in condensed matter physics with radioactive ion beams. Using co-linear optical pumping, a 8Li+ ion beam having a large nuclear spin polarisation and low energy (nominally 30 keV) can be generated. When implanted into materials these ions penetrate to shallow depths comparable to length scales of interest in the physics of surfaces and interfaces between materials. Such low-energy ions can be decelerated with simple electrostatic optics to enable depth-resolved studies of near-surface phenomena over the range of about 2-200 nm. Since the β-NMR signal is extracted from the asymmetry intrinsic to beta-decay and therefore monitors the polarisation of the radioactive probe nuclear magnetic moments, this technique is fundamentally a probe of local magnetism. More generally though, any phenomena which affects the polarisation of the implanted spins by, for example, a change in resonance frequency, line width or relaxation rate can be studied. The β-NMR program at ISAC currently supports a number of experiments in magnetism and superconductivity as well as novel ultra-thin heterostructures exhibiting properties that cannot occur in bulk materials. The general purpose zero/low field and high field spectrometers are configured to perform CW and pulsed RF nuclear magnetic resonance and spin relaxation experiments over a range of temperatures (3-300 K) and magnetic fields (0-9 T). © 2013 Springer Science+Business Media Dordrecht.
Kozaczuk J.,TRIUMF Laboratory Particle and Nuclear Physics
Journal of High Energy Physics | Year: 2015
Abstract: The standard picture of electroweak baryogenesis requires slowly expanding bubbles. This can be difficult to achieve if the vacuum expectation value (VEV) of a gauge singlet scalar field changes appreciably during the electroweak phase transition. It is important to determine the bubble wall velocity in this case, since the predicted baryon asymmetry can depend sensitively on its value. Here, this calculation is discussed and illustrated in the real singlet extension of the Standard Model. The friction on the bubble wall is computed using a kinetic theory approach and including hydrodynamic effects. Wall velocities are found to be rather large (vw ≳ 0.2) but compatible with electroweak baryogenesis in some portions of the parameter space. If the phase transition is strong enough, however, a subsonic solution may not exist, precluding non-local electroweak baryogenesis altogether. The results presented here can be used in calculating the baryon asymmetry in various singlet-driven scenarios, as well as other features related to cosmological phase transitions in the early Universe, such as the resulting spectrum of gravitational radiation. © 2015, The Author(s).
TRIUMF Laboratory Particle and Nuclear Physics | Date: 2013-04-25
A process for producing technetium-99m from a molybdenum-100 metal powder, comprising the steps of: