General Lab Information

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User Guide | Applying for Beam Time

Beam Time Allocation

The total amount of beam time available on a beamline each cycle is a combination of the time required for commissioning, maintaining, and upgrading the beamlines (called “technical commissioning” time) and the time available for user experiments (called the “user-available” time). As new beamlines come online, they transition from a majority of technical commissioning (TC) time to a majority of user-available (UA) time.

Each cycle, beamlines may designate a fraction of their UA time for “science commissioning (SC)” experiments and allocate appropriate GU proposals for this purpose. Science commissioning is aimed at engaging the scientific community in user-assisted commissioning of new beamlines and/or newly implemented endstation capabilities. Science commissioning activities must be described in the GU proposal in order to be considered for SC time. Due to the commissioning nature of these activites, science commissioning beam time is not guaranteed.

The TC and UA fractions are determined by management in consultation with beamline staff prior to each run cycle. The use of TC and SC time by each beamline is reviewed each cycle by NSLS-II management to ensure that it is appropriate and justified.

Once a beamline reaches mature operations, which is typically ~1 year after “first light”, a minimum of 50% of the UA time is allocated to a combination of GU, BAG, and RA proposals every run cycle. Up to 35% of the UA time may be allocated to PU proposals and up to 15% of the UA time may be allocated for beamline discretionary time.

Beam time allocation and scheduling

Each cycle, the Proposal Review Panels review and score new proposals and recommend shift allocations for the initial cycle and the lifetime of the proposal. Allocations of new proposals and existing BTRs are done in score order for each beamline. When scores are close to the cutoff score, and there are clusters of proposals around the cutoff, the allocation panel may also consider whether the proposal is from a new user, whether returning users have been well-prepared and productive, and whether the group has published work from prior beam time.

Once allocation recommendations are made, they are approved and finalized by management. Users are notified of the results of the review process via the PASS system and the Lead Beamline Scientist at each beamline is responsible for the scheduling.