SLAC National Accelerator Laboratory

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  • Edward I. Solomon

    Edward I. Solomon

    Monroe E. Spaght Professor of Chemistry and Professor of Photon Science

    Current Research and Scholarly InterestsProf. Solomon's work spans physical-inorganic, bioinorganic, and theoretical-inorganic chemistry, focusing on spectroscopic elucidation of the electronic structure of transition metal complexes and its contribution to reactivity. He has advanced our understanding of metal sites involved in electron transfer, copper sites involved in O2 binding, activation and reduction to water, structure/function correlations over non-heme iron enzymes, and correlation of biological to heterogeneous catalysis.

  • Joachim Stöhr

    Joachim Stöhr

    Professor of Photon Science, Emeritus

    1968 Vordiplom in Physics, Bonn University, Germany
    1971 M.S. in Physics, Washington State University, USA
    1974 Dr. rer. nat. in Physics, TU München, Germany

    Professional History:
    Scientist at Lawrence Berkeley Laboratory (1976-77)
    Senior Research Associate at Stanford Synchrotron Radiation Laboratory (1977-81)
    Senior Staff Physicist at Exxon Research and Engineering Company (1981-85)
    Research Staff Member at IBM Almaden Research Center (1985-89)
    Manager, Department of Condensed Matter Science, IBM ARC (1989-91)
    Manager, Department of Magnetic Materials and Phenomena, IBM ARC (1991-94)
    Manager, Synchrotron Radiation Project, IBM ARC (1994-95)
    Research Staff Member at IBM ARC (1995-99)
    Professor of Photon Science, Stanford University (2000 – 2017)
    Deputy Director, Stanford Synchrotron Radiation Lightsource (SSRL) (2000-2005)
    Director, SSRL (2005-2009)
    Director, Linac Coherent Light Source (LCLS) (2009-2013)
    Professor Emeritus (2017 – present)

    Fellowships, Awards, Honors:
    Fulbright Scholarship 1969-70
    Postdoctoral Scholarship from Deutsche Forschungsgemeinschaft 1975-76
    Fellow of the American Physical Society since 1988
    Adjoint Professor in Physics at Uppsala University, Sweden (1993-2000)
    Consulting Professor at Stanford Synchrotron Radiation Laboratory (1994-1999)
    IBM Outstanding Technical Achievement Award 1997
    Hofstadter Lecture, Stanford University, 2010
    Davisson-Germer Prize 2011 in Surface Physics from American Physical Society
    Ångstrom Lecture, Uppsala University, 2017

    Summary of Scientific Work:
    My early scientific research focused on the development of x-ray based surface techniques, especially surface EXAFS and NEXAFS, and their use for the determination of the geometric arrangement and bonding of atoms, molecules and thin organic films on surfaces. This work is summarized in my review article “SEXAFS: Everything you always wanted to know about SEXAFS but were afraid to ask” (in X-Ray Absorption: Principles, Applications, Techniques of EXAFS, SEXAFS and XANES, Edits. D. Koningsberger and R. Prins, Wiley, 1988) and my 1992 book “NEXAFS Spectroscopy” (Springer).

    My later research focused on magnetic materials and phenomena, in particular the study of magnetic thin films, interfaces and nanostructures, and their ultrafast dynamics by use of forefront x-ray techniques. This work forms the foundation of my 2006 book (with H. Siegmann) entitled “Magnetism: From Fundamentals to Nanoscale Dynamics” (Springer).

    With the advent of x-ray free electron lasers (XFELs) around 2010 my research increasingly focused on the description of x-rays and their interactions with matter within modern quantum optics, leading to my 2023 book “The Nature of X-Rays and their Interactions with Matter”.
    In total I have written 3 books, 10 review articles in the form of book chapters and about 250 scientific Journal publications. I hold 5 patents and have given more than 150 invited talks at international scientific conferences, about 100 colloquia at Universities and Scientific Research Institutions, and 3 public lectures on the topic of magnetism and x-ray free electron lasers.

    More information on my career, research, students and postdocs is given on my Stanford website:

  • Hirohisa A. Tanaka

    Hirohisa A. Tanaka

    Professor of Particle Physics and Astrophysics

    Current Research and Scholarly InterestsParticle physics and astrophysics, neutrino properties, dark matter

  • Sami Gamal-Eldin Tantawi

    Sami Gamal-Eldin Tantawi

    Professor of Particle Physics and Astrophysics

    BioFor over a decade I have advocated for dedicated research efforts on the basic physics of room temperature high gradient structures and new initiatives for the associated RF systems. This required demanding multidisciplinary collaboration to harness limited resources. The basic elements of the research needed to be inclusive to address not only the fundamentals of accelerator structures but also the fundamentals of associated technologies such as RF manipulation and novel microwave power sources. These basic research efforts were not bundled with specific developments for an application or a general program. The emerging technologies promise a broad, transformational impact.

    With this underlying philosophy in mind, in 2006 the US High Gradient Research Collaboration for which I am the spokesman was formed. SLAC is the host of this collaboration, which comprises MIT, ANL, University of Maryland and University of Colorado, NRL and a host of SBIR companies. This led to the revitalization of this research area worldwide. The international collaborative effort grew to include KEK in Japan, INFN, Frascati in Italy, the Cockcroft Institute in the UK, and the CLIC team at CERN.

    This effort led to a new understanding of the geometrical effects affecting high gradient operations. The collaborative work led to new advances in understanding the gradient limits of photonic band gap structures. Now we have a new optimization methodology for accelerator structure geometries and ongoing research on alternate and novel materials. These efforts doubled the usable gradient in normal conducting high gradient linacs to more than 100 MV/m, thus revitalizing the spread of the technology to other applications including compact Inverse Compton Scattering gamma-ray sources for national security applications, and compact proton linacs for cancer therapy.

  • Caterina Vernieri

    Caterina Vernieri

    Assistant Professor of Particle Physics and Astrophysics

    BioCaterina Vernieri received her PhD on the CMS experiment from the Scuola Normale Superiore in Pisa, Italy, in 2014 and then moved to Chicago for a postdoctoral fellowship at the Fermi National Accelerator Laboratory. She joined SLAC in 2018 as a Panofsky Fellow and moved to the ATLAS experiment, and in 2022 she became Assistant Professor.
    Throughout this time, she has been devoted to studying the Higgs boson using data from the LHC. She co-led the group in the CMS experiment studying the Higgs decay to b quarks at the time that this important decay process was finally discovered in the data. At SLAC, Caterina is working with the ATLAS experiment at the LHC with a focus on Higgs physics. She is responsible for the integration activities at SLAC of the new ATLAS Pixel Inner Tracker detector.
    She was also co-convener of the group on Higgs boson properties in the US national study of the future of particle physics.

  • Soichi Wakatsuki

    Soichi Wakatsuki

    Professor of Photon Science and of Structural Biology

    Current Research and Scholarly InterestsUbiquitin signaling: structure, function, and therapeutics
    Ubiquitin is a small protein modifier that is ubiquitously produced in the cells and takes part in the regulation of a wide range of cellular activities such as gene transcription and protein turnover. The key to the diversity of the ubiquitin roles in cells is that it is capable of interacting with other cellular proteins either as a single molecule or as different types of chains. Ubiquitin chains are produced through polymerization of ubiquitin molecules via any of their seven internal lysine residues or the N-terminal methionine residue. Covalent interaction of ubiquitin with other proteins is known as ubiquitination which is carried out through an enzymatic cascade composed of the ubiquitin-activating (E1), ubiquitin-conjugating (E2), and ubiquitin ligase (E3) enzymes. The ubiquitin signals are decoded by the ubiquitin-binding domains (UBDs). These domains often specifically recognize and non-covalently bind to the different ubiquitin species, resulting in distinct signaling outcomes.
    We apply a combination of the structural (including protein crystallography, small angle x-ray scattering, cryo-electron microscopy (Cryo-EM) etc.), biocomputational and biochemical techniques to study the ubiquitylation and deubiquitination processes, and recognition of the ubiquitin chains by the proteins harboring ubiquitin-binding domains. Current research interests including SARS-COV2 proteases and their interactions with polyubiquitin chains and ubiquitin pathways in host cell responses, with an ultimate goal of providing strategies for effective therapeutics with reduced levels of side effects.

    Protein self-assembly processes and applications.
    The Surface layers (S-layers) are crystalline protein coats surrounding microbial cells. S-layer proteins (SLPs) regulate their extracellular, self-assembly by crystallizing when exposed to an environmental trigger. We have demonstrated that the Caulobacter crescentus SLP readily crystallizes into sheets both in vivo and in vitro via a calcium-triggered multistep assembly pathway. Observing crystallization using a time course of Cryo-EM imaging has revealed a crystalline intermediate wherein N-terminal nucleation domains exhibit motional dynamics with respect to rigid lattice-forming crystallization domains. Rate enhancement of protein crystallization by a discrete nucleation domain may enable engineering of kinetically controllable self-assembling 2D macromolecular nanomaterials. In particular, this is inspiring designing robust novel platform for nano-scale protein scaffolds for structure-based drug design and nano-bioreactor design for the carbon-cycling enzyme pathway enzymes. Current research focuses on development of nano-scaffolds for high throughput in vitro assays and structure determination of small and flexible proteins and their interaction partners using Cryo-EM, and applying them to cancer and anti-viral therapeutics.

    Multiscale imaging and technology developments.
    Multimodal, multiscale imaging modalities will be developed and integrated to understand how molecular level events of key enzymes and protein network are connected to cellular and multi-cellular functions through intra-cellular organization and interactions of the key machineries in the cell. Larger scale organization of these proteins will be studied by solution X-ray scattering and Cryo-EM. Their spatio-temporal arrangements in the cell organelles, membranes, and cytosol will be further studied by X-ray fluorescence imaging and correlated with cryoEM and super-resolution optical microscopy. We apply these multiscale integrative imaging approaches to biomedical, and environmental and bioenergy research questions with Stanford, DOE national labs, and other domestic and international collaborators.