From the Director
Severe winter weather contributed to loss of electrical power to SSRL/SPEAR3 on several occasions during our current FY 2024 run. In mid-January, storm-related water intrusion into the housing of a large power transformer feeding the SPEAR3 booster complex catalyzed a multi-step failure of the transformer. In early February, severe winds during another atmospheric river storm caused the downing of many trees, including one that caused the loss of power to the SLAC site’s main 230 kV electrical line. In early March, a brief but intense storm produced a power instability on the 230 kV line that caused our local power utility, Pacific Gas & Electric, to de-energize the line.
There was no permanent damage to SSRL systems during these events, but they, unfortunately, resulted in lost beam time to our users. These events point out the need for us to invest in back-up systems and hardening of the facility to mitigate what are likely to be increasingly frequent severe weather events in future years. We received funds at the end of FY 2023 from the Department of Energy Basic Energy Sciences to order replacements of key power transformers around SSRL. These have been ordered and will be installed. The recent increase in SSRL’s operating funds provides much-needed resources for maintenance and risk mitigation which we will use over the coming years to improve SSRL’s operational resilience.
Earlier this year, we reorganized the SSRL leadership team. Xiaobiao Huang now leads the Accelerator Division. James Safranek, who had previously led the Division, now leads the Accelerator Physics Department. Dan Harrington leads the Beam Line Systems Division as well as the Beam Line Development and Support Department. This change allows Tom Rabedeau to focus on SSRL’s future project portfolio, including plans for Major Item of Equipment project for new beam lines at SSRL.
– Paul McIntyre
SSRL SPEAR3 Celebrates 20 Years
SSRL utilizes x-rays produced by its accelerator, the Stanford Positron Electron Asymmetric Ring (SPEAR). This month we celebrated the 20th anniversary of the 2004 upgrade funded by the Department of Energy and the National Institutes of Health. SPEAR3 is a 3-GeV, high-brightness third generation storage ring operating with low emittance. SSRL runs with 500 mA in top-off mode, with the beam current kept constant by injection of electrons into the ring every five minutes. The intense beam of synchrotron radiation – ultraviolet and x-ray photons emitted by the circulating electron beams – are used for basic and applied research in diverse fields. SSRL celebrated with a lunch where Paul McIntyre acknowledged the milestone and Bob Hettel who was part of the original SPEAR3 team shared some memories of the people who made the upgrade possible.
SSRL Science Highlights
Nanoscale Chemical Imaging with Structured X-ray Illumination – Contact: Yijin Liu (The University of Texas at Austin)
High-resolution x-ray imaging can reveal chemical details in a number of fields including detection of metal contaminations in Si wafers; electrode dissolution and precipitation in lithium-ion batteries; and metal poisoning in catalytic materials for petroleum refinery – among others. However, using existing methods to balance resolution, sensitivity, and speed simultaneously has been challenging. A proposed new method integrates a full-field transmission x-ray microscope with an x-ray fluorescence detector to map at nanoscale without resorting to nanoscale x-ray focusing and raster scanning. This technique opens up opportunities across multiple fields by using x-rays to bridge the gap between structural and chemical characterizations. Read more...
Pinning the Geometrically-frustrated Flat Band to the Fermi Level with Electron Correlation – Contacts: Jianwei Huang and Ming Yi (Rice University); Makoto Hashimoto and Donghui Liu (SSRL)
Topological flat bands in quantum materials represent a fascinating subject in condensed matter physics, often associated with numerous exotic phenomena, including superconductivity, magnetism, and charge density wave order. Flat bands are commonly found in quantum materials where the Coulomb interactions are comparable or larger than the electron kinetic energy. Searching for flat bands in real materials and uncovering the related intriguing phenomena as well as the underlying microscopic mechanisms are collectively referred to as flat band physics. Read more...
Unique Novel Drug Shows Promise Against SARS-CoV-2 – Contacts: Long Mao and Can Jin (ACEA Therapeutics, Inc.)
Olgotrelvir (STI-1558) is a novel antiviral drug designed to address the challenges posed by the emergence of new, more infectious and virulent SARS-CoV-2 variants. This drug is particularly important for populations at risk who may not benefit from existing treatments like Paxlovid due to potential drug-drug interactions. Olgotrelvir exhibits strong antiviral activity against the SARS-CoV-2 main protease (Mpro), including its variants which showed resistance to Paxlovid. Furthermore, it inhibits human cathepsin L (CTSL), a host enzyme critical for viral entry through the endosomal pathway, thereby blocking both the entry and replication of the virus. Phase 1 clinical trials have demonstrated that oral administration of Olgotrelvir achieves effective plasma levels with limited mild adverse effects and a promising reduction in viral RNA load. Read more...
SSRL-Related Science
A Newly Published Protein Structure Helps Explain how Some Anti-cancer Immunotherapy Treatments Work
Excerpt from Stanford News Article by Erin Ross
Some cancerous tumors hijack proteins that act as “brakes” on our immune system and use them to form a sort of shield against immune recognition. Immunotherapy treatments have been created that turn off these “brakes” and allow our body to attack foreign-looking cancer cells. To further advance such treatments, researchers at Stanford University, SSRL and New York University have recently published a new structure of one of these brake proteins, LAG-3 in the Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2310866121. Their work contains key details of the molecule’s structure, as well as information about how the LAG-3 protein functions.
Jack Silberstein, a PhD student in immunology, co-led the work and colleagues, including Daniel Fernandez in Stanford’s Sarafan ChEM-H Macromolecular Structure Knowledge Center and Irimpan Mathews at SSRL began working on LAG-3’s structure in 2019. The team used SSRL's macromolecular crystallography beamline 12-1 to collect the data that eventually led to determining the structure. Read more...
