ALS-U Timeline & Facility Impacts

In September 2016, DOE initiated the ALS-U project by approving its “mission need” and assigning it critical decision (CD)-0 status, the first milestone in making the upgrade a reality. Over the next several years, the project team completed engineering and design work, and the project was baselined. In November 2022, the project received approval to start construction, known as CD-3. This page outlines the remaining steps and anticipated impacts on the user community.

• Before the Dark Time
• During the Dark Time
• Transition to Operations
• Ramp-Up to Full Performance
• User Proposal Expectations
• Feedback and Questions

ALS-U Project Schedule Update

Before the Dark Time 

In summer 2023, installation of the accumulator ring magnets began. Construction of this “damping” ring is ongoing during regular shorter and longer ALS shutdowns. The ALS will continue to provide as much beam as possible to users until the dark time begins.

What to Expect

Shutdowns

DISCLAIMER: The ALS is currently under a summer shutdown that began in July. We will update this page with information on the winter shutdown later this fall. Please check back for updates.

• Increased down time is required to install the accumulator ring and to complete as much work as possible for the storage-ring seismic retrofit and radiation shielding upgrade before the dark time.
• The schedule for long shutdowns to accomplish this work is likely to continue to be two ~13-week shutdowns per year, beginning in January and July.
• Regular shorter maintenance shutdowns and accelerator physics shifts will continue as usual. They are critical to maintain reliable operation of the current ALS, and accelerator physics time helps minimize the ALS-U commissioning risk.
• See the Operating Schedule for the latest information.

Beamlines: Updates will be coming later this year. 

• Most beamlines will operate until the dark time begins.
• A few beamlines (in particular 8.0.1 and 10.0.1) may need to be turned off a few weeks or months before the dark time for preparatory work.
• See the Post-ALS-U Beamline Status Table on this page for more information.

During the Dark Time 

The facility’s dark time, the timeframe without any user operations, is when the present-day ALS storage ring will be removed and a new ring built and commissioned in its place. Storage-ring removal and installation during this time will be longer than originally expected due to preparation of the site and storage-ring commissioning. Bend-magnet beamlines will be moved and some beamline upgrades will be performed, and beamline commissioning will begin. Please check back for more details on this as we continue to work on the schedule. In total, the dark time is currently expected to last at least two years. 

What to Expect

• The accelerator will be turned off until storage-ring commissioning begins; there will be no user operations on the experimental floor.
• The experimental floor will be a construction zone with very limited access.
• Additional construction impacts include changes to pedestrian and vehicular traffic routes, some additional noise and vibration, and power and cooling-water outages of a few days each at the beginning and end of the dark time.

Transition to Operations

The dark time will be followed by a six-month transition to operations period, when beamlines will be brought back online and accelerator commissioning will continue. The ALS-U project team is currently working to determine the order in which beamlines will be turned on.

What to Expect

• Operations during this period will likely be characterized by low current, beam instabilities, and beam interruptions. Early experiments may therefore be most appropriately carried out by beamline scientists. Collaborative access with users may be possible, but the ALS will not return to regular user operations during this phase.
• Beamlines that have returned to operation may require further commissioning past the transition to operations period or may need to wait for the storage-ring current to reach a certain value at which experiments become feasible for full user operations to resume on that particular beamline.
• Additional time past the transition to operations period will be needed to return all beamlines to operation.

The ALS-U project will end when CD-4 is approved upon demonstration of the project’s threshold key performance parameters (KPPs).

ALS-U project key performance parameters (KPPs). Threshold KPPs must be achieved before the project can end. Objective KPPs are the desired operational goal.

Ramp-Up to Full Operations

Accelerator development and beamline commissioning will continue. Any beamlines not yet returned to operations will be brought online.

What to Expect

• Available beamtime will increase as the accelerator current ramps up and beam instabilities are mitigated and interruptions decrease.
• Another six months (one year past the end of the dark time) or more may be needed to get to a full steady state of user operations. It could take longer to reach the target current of 500 mA.

User Proposal Expectations

UPDATE: While the ALS-U project is undergoing schedule planning and preparing for the installation of the new accelerator, we will continue to provide access to users until the beginning of the dark time. Since an earlier dark time in 2026 is possible, our goal is to ensure that currently active proposals receive the beamtime needed to successfully conclude their experiments. As of August 2025, we will not issue a September 2025 call for new General User Proposals (GUPs) for January–July 2026. Users are encouraged to submit a Beamtime Request (BTR) to seek beamtime for their currently active proposals. The RAPIDD access path will be open for urgent access requests and for experiments that can be finished within a single cycle. 

• Before the dark time: At this time, we expect to only allow existing GUPs to submit BTRs. For proposals set to expire in December 2025, we will allow one final additional BTR. RAPIDD access proposals will continue to be accepted for urgent BTRs. GUPs will become inactive and end at the start of the dark time. New proposals will need to be submitted as the upgraded facility comes back online. With ALS and PI concurrence, Approved Programs (APs) will be paused at the dark time and restart when collaborative access becomes available at the relevant beamline.
• During the dark time: The facility will be closed for construction; there will be no beamline operations.
• Transition to operations: Beamlines will be in commissioning. There will be no general user operations, but collaborative access may be possible.
• Ramp-up to full operations: RAPIDD proposals will be phased in as beamlines become available. Formal proposal calls will resume when beamlines are fully operational.

Feedback and Questions

Feedback and questions are welcomed.

• Submit a question or comment to ALS leadership via this form
• Email a member of ALS leadership (see staff directory)
• Contact the Users’ Executive Committee at alsuec@lbl.gov
• For specific questions about beamline capabilities, you may also contact the beamline scientist