The Advanced Photon Source
a U.S. Department of Energy Office of Science User Facility

APS Operations and General User Programs During the COVID Pandemic

APS operations update: Revised July 29, 2021

Based on the most recent CDC guidance, all individuals regardless of vaccination status are required to wear masks while on site. Face coverings must be worn in all public and work areas within a building (e.g., shared offices and labs, hallways, elevators, restrooms). Face coverings are required in all face-to-face meetings and at security checkpoints (though security may ask you to lower your face covering to verify identity). Face coverings are also required inside government-owned vehicles when another person is in the vehicle. Face coverings may be removed when alone in an enclosed space or when necessary to eat, provided you are six feet away from other people. Face coverings are required outdoors only when you are within six feet of another person.

All employees and APS users must maintain a minimum of six feet of distance from others while onsite.

Argonne and the APS remain in a state of limited operations. Mail-in/remote experiments continue, and on-site experimenter presence is permitted ONLY for experiments that have gone through a pre-approval process based on need for access. The number of users allowed on site also remains capped on a per-experiment basis.

External users should be prepared to show proof of vaccination.

Requests for onsite experiment access and any general questions concerning the policy above should be sent to


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