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Beamtime Requests at SER-CAT

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The SER-CAT Director will designate a Beamline Scheduling Manager (BSM) to maintain the beamline scheduling system for SER-CAT. Requests for scheduling will be done via e-mail to the BSM. The BSM will also maintain Beamline Schedule pages for each beamline for members to check the current beamline schedules. Beamline scheduling will be done on an operating cycle basis for each beamline. The general procedure is as follows:

  1. Beamline Operations Schedule: APS Experimental Facilities Division will release the Beamline Operations Schedule for the next operations cycle. This schedule includes times designated for maintenance, machine studies and user operations. The APS schedule is divided into 8-hour shifts (midnight to 0800, 0800 to 1600, 1600 to 2400). However, SER will schedule according to the following pattern:

    DesignationShifts for Beamline (Chicago time-zone)
    9:00am - 9:00pm
    11:00am - 11:00pm
    9:00pm - 9:00am
    11:00pm - 11:00am


  2. SER-CAT BSM will schedule all user beamtime in slots, which will consist of either 12-hour or 24-hour periods, beginning at 9:00AM or 9:00PM (22-ID-D), or at 11:00AM or 11:00PM (22-ID-E) (see above). Some slots are shorter by one to three hours; this is due to the designation of time for Machine Studies by the APS (typically, but not always, a Sunday evening/Monday morning slot). Machine Studies begin at 8:00AM, Monday morning; there is no user x-ray beamtime available during Machine Studies.
  3. Pucks are loaded into the robot dewars at the beginning of your shift. This means you will not be starting your experiment until after the pucks are loaded and the D-station hutch is searched and secured. The length of time required depends upon the number of pucks being removed for the previous group(s), as well as the number being loaded for your group.
  4. Operational Slots: The BSM will designate any operational slots required for beamline development, testing, diagnostics, repair, etc. Provisions are also made for emergency/unscheduled repairs (see below).
  5. GUP Requirements: Up to 50% of total user beamtime needs to be available for the APS General Users Program (GUP). A Beamtime Allocation Committee (BAC) will assign GUPs to the SER-CAT beamlines, and the BSM will schedule these GUP Users.
  6. MAT Time Slots: One 12-hour shift will be reserved for Member Access Time (MAT) on each of the beamlines, 22-ID-D and 22-ID-E, once per week. MAT time will be assigned to staff-assisted data collections, as well as special requests from member institutions. The final 24-72 hours during each run will also be reserved as MAT time on each of the beamlines.
  7. Any Remaining Slots: The remaining operational slots will be available for member users. The BSM will calculate the number of shifts available of each type for each member. The BSM will send e-mail to each SER-CAT institutional representative and SER-CAT institutional alternate indicating that a new operation cycle has been posted on the APS website and how many slots of each type have been designated for each member for that cycle. A copy of the run schedule for each beamline, with slots to be used by independent investigators and staff blocked out, will be available to facilitate ease of planning for SER-CAT members.
  8. Bidding: Each member can then bid on which slots they want to use, up to the maximum number of slots available per member, from the schedule by sending an e-mail message to the BSM. Each member will define their first, secondary, and tertiary choices, as well as any days that can not be used.
  9. The BSM will create beamtime assignment schedules for the member groups and post the schedules on the SER-CAT website, with an accompanying e-mail to institution representatives, announcing the web page posting. In the event of conflicting requests for specific slots, the BSM will choose one member to receive the slot. Slots will be scheduled by the BSM on a first-come, first-served basis, taking into consideration such items as previous schedules (i.e., weekend vs. weekday assignments), individual member preferences (insofar as possible) and time of receipt of the request (all requests received before the e-mail call for beamtime preferences will be treated as having been received in response to the request; requests after the e-mail announcement will be handled in the order in which they are received).
  10. Banking: In addition, the BSM will maintain a bank for each beamline for each member. For each scheduling period, each member has the option of: scheduling as many slots as designated (the member's bank is unchanged), scheduling fewer slots than designated (any unused slots are then placed in the bank and can be used in a subsequent operation cycle). Any additional unused slots that cannot be banked are lost. If scheduling more slots than designated, any additional slots come from the member's bank. A maximum of two slots per beamline can be unbanked for each operation cycle.
  11. Banking Limits: Banked days do not expire, but a member can only bank 1 day per share, rounded up. Therefore, if a member owns 3 shares, then that member may keep a maximum of 3 days in the bank.
  12. Banking Constraints: Members may bank their selected slots up to fourteen days prior to the shift. Members can engineer exchanges among themselves for scheduled slots up until 24 hours before the slot begins (see below).
  13. Run-Wide ESAFs are set up, to cover the entire run.  All Run-Wide ESAFs must list: all projects active in the research laboratory (regardless of whether crystals have been observed, or not), and all possible experimenters who might conceivably collect data during the run.  APS Registration constraints may dictate that some experimenters are unable to collect data at the beginning of the run; if their registration is approved during the run, the experimenter must e-mail the BSM with this information.  Once their status is updated on the Run-Wide ESAF, they will be able to collect data for the remainder of the run.  



  1. Unusable slot: If a slot is unusable due to machine or beamline maintenance, it is not counted against the member. The member has three options:
    • They can reschedule the slot(s) from any available slot(s) in the current cycle.
    • They can reschedule the slot(s) in the next cycle (in addition to all the designated and banked slots for the next cycle).
    • They can bank the unusable slot in their bank for future use. Unusable slots are not subject to the banking limits above. However, if the member chooses to bank the unusable slots, they are then subjected to the subsequent unbanking rules described above.
  2. Unused slot: If a member does not show up for a scheduled, usable slot, this will be considered equivalent to having used the slot. The BSM can reassign any slots not being used by a member.
  3. Unassigned slots: Any unscheduled slots can be used by any member by unbanking time from their bank account. If no member wishes to use an unassigned slot, the BSM can offer the shift to a GUP User, to the staff, or to collaborators for their own research.
  4. Assigning slots: A member with a scheduled slot has the option of re-assigning their slot to another user. It is the responsibility of the member to inform the BSM who the actual user of the slot will be. The beamline schedule will be changed to indicate the newly assigned slot user. Time that is given away is neither charged against the original user, nor is it considered banked.
  5. Reassignment of slots: Reassigning may take the form of an equal trade of slots. Arranging slot swaps are the responsibility of the members and do not alter the members' slot/bank account. Slot swaps should be reported to the BSM so that the web page can be updated to reflect the new schedule.
  6. End of slot: The scheduled user must be completely off the beamline (i.e., hutch cleaned out, personnel off the experimental floor, etc.) fifteen minutes before the end of their scheduled slot. The new scheduled user has the right to request termination of a prior user's experiment.
  7. Disputes: The BSM is the final arbitrator of any scheduling disputes. It is hoped that the members will work in a fair-minded way to maximize equal usage of the facility.