The Monthly Webinar Series focuses on research being conducted at the partner labs of the Nuclear Science and Security Consortium.
Our webinars serve as an opportunity for our students to connect with lab scientists and learn about projects looking for student researchers.
If you or someone you know would be interested in presenting a webinar contact firstname.lastname@example.org
Our Webinar series in hiatus for Summer 2017. See you again in the Fall!
Improving beta-decay studies for fundamental science and applications
Dr. Nicholas Scielzo
April 13th, 2017
Recent advances in radioactive-ion beams and ion-trapping techniques are opening up new opportunities for improved studies of the neutrinos and neutrons emitted in nuclear beta decay. A novel ion-trap system has been developed to address fundamental questions ranging from electroweak theory to the origin of the elements and to provide nuclear data for nuclear-energy and stockpile-stewardship applications. When a radioactive ion decays in the trap, the recoil-daughter nucleus and emitted particles emerge from the trap volume with negligible scattering and propagate unobstructed through vacuum. This allows the momentum and energy of particles that would otherwise be difficult (or even impossible) to detect to be reconstructed from the momentum imparted to the recoiling nucleus. Beta-delayed neutron spectroscopy can be performed by circumventing the difficulties associated with direct neutron detection and instead reconstructing the neutron emission probabilities and energy spectra from the time of flight of the recoiling nuclei. In addition, a determination of the direction and energy of each emitted neutrino in the decays of 8Li and 8B has been performed to search for new particles and interactions. Recent results from decay studies using the Beta-decay Paul Trap (BPT) at Argonne National Laboratory will be presented and future prospects for these approaches will be discussed.
Dr. Nicholas Scielzo is currently a Deputy Group Leader for the Nuclear Particle Physics Group within the Nuclear and Chemical Sciences Division at LLNL. He earned a BA in chemistry and physics from Harvard University in 1997 and a PhD in physics from the University of California at Berkeley in 2003. He arrived at LLNL in 2006 as a Lawrence Fellow after spending 3 years at Argonne National Laboratory developing novel techniques to test the Standard Model of particle physics using short-lived radioactive nuclei. At LLNL, he has established a multi-faceted beta-decay spectroscopy program that uses ion traps, radioactive beams, and an assortment of specialized radiation detectors to perform neutrino and neutron spectroscopy to test the electroweak interaction, improve our understanding of heavy-element nucleosynthesis, and provide high-quality nuclear data for stockpile-stewardship and reactor-modeling applications. He has also developed new techniques to search for neutrinoless double-beta decay and to determine reaction cross sections on radioactive isotopes. In the last several years he has served as the primary advisor for 4 graduate students who received their PhD from the University of California at Berkeley.
Spatially Resolved Uranium Speciation in Nuclear Materials by Scanning Transmission X-ray Microscopy
Dr. David Shuh
February 28th, 2017
The production and manipulation of nuclear material can leave distinct physical and chemical signatures, which can later be characterized to provide evidence of the origin and process history of an unidentified specimen, a field known as ‘nuclear forensics’. A broad variety of analytical chemistry techniques can provide information about interdicted and post-detonation materials. Here, we present the results of several research studies of uranium-bearing forensic specimens by soft X-ray scanning transmission X-ray microscopy (STXM). STXM yields X-ray absorption spectroscopy data with 25-nm or better spatial resolution, making it possible to quantitatively evaluate variations in oxidation state and other chemical properties across a heterogeneous specimen. Operating in the soft X-ray regime provides access to the NIV,V edges of the actinides and the oxygen K edge, which is highly sensitive to variations in U-O bonding, and consequently carries unique fingerprints of uranium oxides and their hydrates. Thus, this approach makes it possible to evaluate the oxidation state and the heterogeneity of nuclear forensic samples, yielding information on formation or process history, and/or past storage conditions. In studies of U-bearing glassy materials, the L edges of some transition metals (particularly iron, which influences the redox behavior of uranium) can provide additional insights. Technical developments in STXM operations relevant to forensics are also summarized. In particular, we report on improvements in sample preparation and rapid data analysis methods implemented in STXM experiments at Beamline 11.0.2 of the Advanced Light Source. LLNL-ABS-690941
Dr. David Shuh is a senior scientist in the Heavy Element Chemistry Group of the Chemical Sciences Division and the Director of the Glenn T. Seaborg Center at LBNL. Dr. Shuh’s research focuses comprehensively on the science of the f-elements, in particular the actinide elements with an emphasis on the transuranic elements (e.g., neptunium, plutonium, americium, curium). He is a world-renowned expert in the development of large-scale synchrotron radiation instrumentation and techniques to explore the fundamental chemistry and physics of f-electron materials. His current interests focus on determining the electronic structure and coordination chemistry of f-electron and novel materials to understand their physical and chemical behavior.
Compact quasi-monoenergetic photon applications and sources for nuclear applications
Dr. Cameron Geddes
January 24, 2017
Near-monoenergetic photon sources at MeV energies offer improved sensitivity at reduced dose for nuclear nonproliferation and related applications. Assessments of application-specific benefit from mono energetic photons will be described, including for cargo screening, active interrogation, treaty verification, nondestructive assay, and emergency response. Thomson (also referred to as Compton) scattering sources are an established method to produce appropriate photon beams. Applications are however restricted by the size of the required high-energy electron accelerator, scattering (photon production) system, and shielding for disposal of the high-energy electron beam. Laser-plasma accelerators (LPAs) produce GeV electron beams in centimeters, using the plasma wave driven by the radiation pressure of an intense laser. Designs, and development of an experimental facility to demonstrate a compact photon source using such accelerators will be described, together with the path to a application-relevant photon source system.
Dr. Geddes is a staff scientist in the BELLA center of Lawrence Berkeley National Laboratory, investigating use of laser driven plasma waves to build compact next generation particle accelerators and photon sources. These accelerators sustain much higher accelerating fields than conventional devices, allowing compact machines. His current project is developing compact sources of near-monochromatic MeV photons for nuclear material detection and characterization
Cryogenic Gamma-ray detectors with Ultra-High Energy Resolution
December 1, 2016
Magnetic microcalorimeter (MMCs) gamma-ray detectors with operating temperatures below 50 mK offer an order of magnitude higher energy resolution than semiconducting Ge and Si detectors. They are based on measuring the change in magnetization after gamma absorption increases the detector temperature. MMCs can have an energy resolution <50 eV at 60 keV, and therefore detect isotopes whose gamma emissions are obscured by line overlap in conventional Ge detectors. The high energy resolution can greatly improve the accuracy of non-destructive analysis of nuclear materials, both in fundamental science and nuclear safeguards applications. We are currently developing arrays of MMC detectors to increase the detector sensitivity. We are also building refrigerators to make operating temperatures of 15 mK accessible fully automated and without the use of cryogenic liquids. This talk discusses the design and performance of MMC gamma detectors at LLNL, and outlines experiments that can serve as thesis project for graduate students who are interested in ultra-high resolution detector development.
Stephan Friedrich received his Ph.D. in Applied Physics from Yale University in 1997 with a dissertation on superconducting tunnel junction X-ray detectors for high-energy astrophysics. He then adapted these detectors for operation at the ALS synchrotron at the Lawrence Berkeley National Lab for biophysics and material science experiments. Since 2002, Dr. Friedrich has led the cryogenic detector group at Lawrence Livermore National Lab, developing ultra-high resolution X-ray and gamma-ray detectors for basic science and national security applications. He has supervised several graduate students who have written their theses on cryogenic detector development and the experiments they enable.
Nuclear Security Programs at Sandia National Laboratories
November 7, 2016
Sheryl Hingorani will describe a variety of Nuclear Security Programs underway at Sandia National Laboratories in Livermore, CA. Sheryl will also discuss opportunities for possible student intern placements.
Sheryl Hingorani leads Sandia’s Systems Analysis and Engineering organization in Livermore, California. Ms. Hingorani started her career at Sandia in 1986, as a mechanical design engineer, and has spent most of her career working in a variety of positions in Sandia’s Nuclear Weapons program, including as Sandia’s Nuclear Weapons Chief of Staff, and as Chair of the independent Red Team for the Annual Assessment of the state of health of the U.S. nuclear stockpile. Ms. Hingorani received a special appointment to Distinguished Member of Technical Staff at Sandia in 1998, and moved into management in 2004. She completed studies as a Fellow with the Massachusetts Institute of Technology Center for International Studies, and was the recipient of the Leadership Foundation Fellowship from the International Women’s Forum. Between 2000 and 2005, Ms. Hingorani was the Executive Director of the Albuquerque Committee on Foreign Relations; she also served as Secretary for the American Committees on Foreign Relations for two years. Ms. Hingorani is a Laboratory Advisor to the Defense Science Board Special Task Force on Weapons of Mass Destruction, and is a Laboratory Affiliate to the California Council on Science and Technology. She is member of the Society of Women Engineers.