Advanced Photon Source: User Access and Beamlines

The Advanced Photon Source (APS) is a high-energy synchrotron light source facility operated by Argonne National Laboratory for the U.S. Department of Energy (DOE) Office of Science. It produces ultra-bright, highly focused hard X-ray beams used to investigate the atomic and molecular structure of materials, biological macromolecules, chemical interfaces, and fundamental physics. Researchers in experimental disciplines like physics, materials science, and crystallography utilize its beamlines to conduct non-destructive, time-resolved diffraction, spectroscopy, and high-resolution imaging experiments.

Following the $815 million Advanced Photon Source Upgrade (APS-U), the facility features an upgraded storage ring operating at an electron beam energy of 6 GeV with a multi-bend achromat (MBA) magnetic lattice. This design reduces electron beam emittance and increases X-ray brightness and coherent flux by up to 500 times compared to the legacy third-generation storage ring. The resulting beam properties enable researchers to track nanoscale structures and sub-picosecond chemical kinetics across diverse scientific sectors.

What the Advanced Photon Source Is

The Advanced Photon Source is a fourth-generation national synchrotron radiation user facility located in Lemont, Illinois, approximately 25 miles southwest of Chicago. Synchrotrons generate radiation by accelerating electrons to relativistic velocities inside a linear accelerator and booster synchrotron before injecting them into a high-vacuum storage ring. As electrons travel around the storage ring, powerful magnetic insertion devices—primarily undulators and wigglers—deflect their path, causing them to emit high-energy electromagnetic radiation concentrated in the hard X-ray spectrum.

Unlike laboratory-scale benchtop X-ray tubes, the synchrotron radiation produced by the APS offers continuous tunability across high photon energies, extreme collimation, and exceptionally high coherence. These properties make it possible to probe dense engineering alloys, battery materials under active cycling, delicate protein micro-crystals, and buried geological strata that cannot be penetrated or resolved by lower-energy soft X-rays.

Who Runs It and What It Covers

The Advanced Photon Source is operated by Argonne National Laboratory, a multi-program science and energy laboratory operated by UChicago Argonne LLC for the DOE Office of Science Basic Energy Sciences (BES) program. Stewardship, core operational funding, and major facility enhancements are managed directly through the BES Scientific User Facilities Division.

The facility encompasses an expansive experimental floor housing 35 sectors arranged around a 1.1-kilometer circumference storage ring. Each sector typically supports two or more distinct beamlines—often divided into an insertion-device beamline and a bending-magnet beamline—resulting in dozens of simultaneously operating experimental endstations. These endstations cover specialized scientific methodologies:

Macromolecular Crystallography (MX): Automated high-throughput structural biology stations determining atomic-resolution models of viruses, membrane proteins, and enzyme-inhibitor drug complexes.
X-ray Absorption Spectroscopy (XAS / XAFS): In situ and operando chemical state determination of catalysts and battery electrodes under operational voltages and temperatures.
Coherent Diffraction and Ptychography: High-resolution nanoscale imaging leveraging coherent X-ray flux to reconstruct three-dimensional specimens without optical lenses.
Small-Angle and Wide-Angle X-ray Scattering (SAXS/WAXS): Structural analysis of soft matter, polymer self-assembly, and complex colloids spanning nanoscale to mesoscale dimensions.
High-Energy Diffraction Microscopy (HEDM): Non-destructive 3D characterization of grain orientations, strain tensors, and void formation in structural alloys under mechanical loads.

The user community comprises thousands of visiting and remote scientists annually from academia, national laboratories, and industry. In common with large physics facilities explored in our analysis of megacollaboration authorship, major synchrotron beamline investigations frequently bring together multi-institutional research groups. Non-proprietary access is open to researchers worldwide free of charge on the condition that results are published openly, while proprietary research is supported under full-cost recovery agreements.

How to Search or Use It

Securing beam time and conducting research at the Advanced Photon Source follows a formal, competitive user cycle. Prospective users must complete the following six operational steps:

Select Beamlines and Consult Beamline Staff: Review the official APS Beamline Directory to compare technical parameters—such as photon energy range (keV), beam size, flux density, detector configurations, and auxiliary sample environments (cryostats, furnaces, diamond anvil cells). PIs must contact the relevant beamline scientists prior to drafting to verify experiment feasibility and schedule requirements.
Register an Argonne Profile and Connect ORCID: Create an Argonne badge profile in the Argonne Information Management System. Every co-investigator on a proposal must link an active ORCID iD in the APS User Portal and designate the Advanced Photon Source as a Trusted Party to validate publishing history and institutional affiliations.
Create a Proposal in the Universal Proposal System: Log in to the online Universal Proposal System (UPS) via the user portal. Select the appropriate proposal track: General User Proposals (GUP) for standard peer-reviewed access valid for up to two years (six cycles); Rapid Access Proposals for urgent, single-cycle investigations; Partner User Proposals (PUP) for groups co-developing beamline instrumentation; or Block Allocation Group (BAG) proposals for consortia conducting automated screening.
Submit Before the Cycle Deadline: APS convenes three proposal cycles per year, with submission deadlines typically falling in March, July, and October. Proposals must articulate the scientific justification, specific beamline requests, and the requested number of 8-hour operational shifts. Proposals are reviewed and scored by independent Proposal Evaluation Panels (PEP) on scientific merit, with beam time awarded by Beamtime Allocation Committees (BAC).
Complete the Experiment Safety Assessment Form (ESAF): Once beam shifts are scheduled, the user team must submit an Experiment Safety Assessment Form (ESAF) through the user portal at least three weeks prior to the scheduled run. The ESAF identifies all chemical, biological, radiological, laser, and pressure hazards, requiring formal sign-off by APS safety coordinators and verification that all participating team members have completed required safety training.
Conduct the Experiment and Transfer Data via Globus: Execute measurements on site or via remote beamline control tools. Detector streams are ingested into the APS Data Management (DM) system and packaged into standardized datasets. After data acquisition, users retrieve files from the dedicated APS Globus collection endpoints directly to their home institutional storage servers.

Strengths and Limits

The Advanced Photon Source provides exceptional research capabilities while operating within specific technical and institutional constraints.

Strengths:

World-Class Coherence and Brightness: Following the multi-bend achromat upgrade to 6 GeV, the APS produces coherent hard X-ray beams up to 500 times brighter than previous generations, enabling sub-micron 3D tomographic reconstructions and ultra-fast dynamic measurements.
Zero User Fee for Open Science: DOE Office of Science sponsorship fully funds beamline operational costs, facility staff, and computational infrastructure for non-proprietary research projects.
Advanced Automated Sample Delivery: High-throughput robotic sample changers, automated liquid-nitrogen cryo-pins, and remote control software permit efficient 24/7 data collection without requiring physical travel to the laboratory.
Integrated Data Pipelines: Automatic ingestion of beamline detectors into structured hierarchical containers accelerates downstream data analysis.

Limits:

High Allocation Competitiveness: Beamlines are consistently over-subscribed, with demand on premier insertion-device endstations exceeding available shifts by factors of two to four.
Rigorous Administrative Lead Times: The mandatory three-week ESAF deadline, security vetting, and safety training require meticulous planning months in advance of experimental runs.
Strict Facility Data Retention Windows: Central facility disks only guarantee retention of experimental data for at least three months following an experiment. Researchers must implement reliable institutional pipelines to curate and share datasets according to their funder-mandated data availability statement.
Scheduled Accelerator Maintenance Shutdowns: Regular accelerator maintenance periods, machine studies, and shutdown cycles interrupt experimental beam delivery throughout the year.

Alternatives

Depending on the photon energy range, spatial resolution, and geographic requirements of a project, researchers can evaluate alternative synchrotron facilities worldwide. The table below compares the Advanced Photon Source with leading international light sources.

Facility Name	Operating Organization	Storage Ring Energy (GeV)	Core Specialization	Proposal System
Advanced Photon Source (APS)	Argonne National Laboratory (DOE BES)	6.0 GeV	High-brightness hard X-rays, MBA lattice, time-resolved imaging	Universal Proposal System (UPS)
National Synchrotron Light Source II (NSLS-II)	Brookhaven National Laboratory (DOE BES)	3.0 GeV	Medium-energy X-rays, ultra-high spatial resolution, soft matter	Proposal Access System (PASS)
European Synchrotron Radiation Facility (ESRF-EBS)	ESRF Intergovernmental Council	6.0 GeV	Extremely Brilliant Source, hard X-ray nanoscopy, structural biology	ESRF User Portal (SMIS)
PETRA III	Deutsches Elektronen-Synchrotron (DESY)	6.0 GeV	Hard X-ray micro-focusing, coherence, materials physics	DESY Online Office (DOOR)
SPring-8	RIKEN / JASRI	8.0 GeV	Very high energy penetration, heavy element materials analysis	SPring-8 User Information (UIAM)

Frequently Asked Questions

Is beam time at the Advanced Photon Source free for academic researchers?

Non-proprietary beam time is allocated free of charge to researchers from academic and research institutions worldwide. To qualify for zero-cost access, researchers must submit a peer-reviewed proposal and commit to publishing all experimental methodologies and findings in the open scientific literature. Proprietary industrial research that retains proprietary data rights requires full-cost recovery reimbursement to the laboratory.

What changed during the Advanced Photon Source Upgrade (APS-U)?

The $815 million APS Upgrade project replaced the original 1990s-era storage ring with an advanced multi-bend achromat magnetic lattice operating at 6 GeV. The upgrade lowered horizontal electron beam emittance and boosted X-ray brightness and coherent flux by up to 500 times, dramatically enhancing resolution for 3D nanoscale imaging, ptychography, and dynamic operando spectroscopy.

What data formats and protocols does the APS support?

APS beamlines standardize on hierarchical container formats, predominantly HDF5 and NeXus (an international standard for neutron, X-ray, and muon science built atop HDF5). These formats store multi-dimensional detector pixel arrays alongside synchronized experimental metadata, sample temperatures, motor positions, and beam energy data. Users retrieve their data files via high-speed Globus transfer endpoints.

How long does the Advanced Photon Source retain experimental user data?

Under the official APS Data Policy, raw and processed experimental data stored on central facility storage systems are guaranteed for a retention period of at least three months after the conclusion of an experiment. Because high-brightness detectors produce hundreds of terabytes during typical runs, the APS does not provide permanent or indefinite archiving; principal investigators and their home institutions are responsible for long-term data preservation.

Can researchers conduct experiments at the APS remotely?

Yes. Many APS beamlines—especially in macromolecular crystallography, small-angle scattering, and routine powder diffraction—offer automated sample changers, cryogenic pin robotics, and secure remote desktop interfaces. Researchers can ship frozen or room-temperature samples directly to Argonne and supervise data collection from their home institutions without traveling to the facility.

Sources

Argonne National Laboratory. “Apply for Beam Time: APS User Program.” Universal Proposal System documentation. Accessed November 7, 2026. https://www.aps.anl.gov/Users/Beam-Time/Apply-for-Beam-Time
Argonne National Laboratory. “Advanced Photon Source Upgrade Project (APS-U).” Facility overview and technical design specifications. Accessed November 7, 2026. https://www.anl.gov/aps-upgrade
Argonne National Laboratory. “APS Data Management and Data Retention Policy.” Advanced Photon Source user procedures and Globus configuration. Accessed November 7, 2026. https://www.aps.anl.gov/Safety-and-Offices/User-Information/APS-Data-Policy
U.S. Department of Energy Office of Science. “Advanced Photon Source: Basic Energy Sciences User Facility Overview.” Accessed November 7, 2026. https://www.energy.gov/science/bes/advanced-photon-source