Timing of Beam Requests and Maintaining Experimental Continuity

In considering the timing of beam allocation, it is important to remember that the EEC meetings, where experiments are approved, take place during a beam period whose schedule is already filled with older experiments. The delivery of beam to an approved new experiment (or one which has exhausted its previously allocated beam) usually proceeds in one of the following scenarios:

1. An experiment may receive approval at a given EEC meeting and be allocated beam time during that very same beam period in which the EEC convened, i.e., to be inserted in the current schedule. This situation is usually manifest for a very high priority experiment on a late breaking system coupled with the circumstance that, during the previous scheduling exercise, there was adequate beam availability to have some of if set aside for this purpose.
2. An experiment that receives approval from the EEC (at some priority) submits a beam request for the following running period - typically 5 months away. If there is adequate beam time available, all requests will be filled. If there is a backlog and/or insufficient beam, requests are filled on a priority basis.
3. An experiment which did not receive a beam time allocation in the next beam schedule after an EEC meeting should receive its allotment in the next schedule after that, but it might be delayed again. In the former case, approximately one year has transpired from the granting of EEC approval. In the latter case the combination of a low priority experiment and inadequate beam availability may allow newer, higher-priority experiments to preempt older but lower-priority studies. If an experiment of medium priority finds itself in this situation, the spokesperson should approach the TRIUMF administration and vigorously argue that insufficient beam time is available for the community's needs.

From these scenarios, it can be seen that there is typically a 6-month to 1-year time lag from EEC approval to finding one's experiment on the beam line.

Users should be made aware of another situation that often arises, and that is one of maintaining experimental continuity in the face of intrinsic scheduling delays. This situation is best illustrated by a rather typical example.

Suppose spokesperson/group Unaware proposes an experiment that requires two weeks of beam to do an initial study, and then, contingent on the results obtained, will need additional beam to mount a longer term program. The EEC approves his proposal, and he is allotted two weeks during the next beam schedule; half a year hence. When the time comes for Unaware to run the experiment, another EEC committee is meeting at the very same time - or had even met before Unware's beam. Because there is nothing to report to that EEC, Unware has to wait half a year for the next EEC meeting. Presuming the initial experiment was successful, that EEC would allocate more beam time, to begin in the next beam period afterwards - another half year wait. Thus, without doing anything wrong, a year has passed between beam periods for the Unaware group.

To avoid this situation, Prof. Unaware should be aware that if his experiment will use up its allotted beam time during the next running period, he should arrange to have something to report to the EEC which will meet concurrent with that experiment, in order to request additional beam time. For an experiment that is having its first run, it is especially critical to have some beam time before the EEC meeting so that preliminary results can be reported. The situation is not so critical for older experiments that are about to run out of allocation, since they should have previous measurements on which to base any further requests for time.