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lhcb-trig L0 trigger requirements and milestones

Date: 12/16/98
Time: 2:07:08 PM
Remote Name:
Remote User: lhcb


Dear colleagues, the time scale for the steps leading to decisions for the L0 baseline implementations are the following: - end 1998: define list of requirements to allow comparison (this mail). - 1/4/98: all implementation studies have provided a written document(s) addressing the requirements. - 1/7/98: if possible the trigger group recommends baseline implementations to the LHCb management, if no agreement within the trigger group: we ask for a review board to decide for us. - mid 2001: TDR ready (real deadline given to referees 31/12/2001).

List of items recommended to be fulfilled by the various implementation studies:

1) An overall scheme of the data flow and its hardware implementation from the Front-End via the actual processors to the L0 decision unit, and the L1 buffer of the output of the trigger. For the calorimeters liaise with the FE designers to agree upon the assumptions. Hopefully this will also be possible for the muons soon (maybe January next year a FE responsible will start his work for the muons).

2) A cost estimate based on the above mentioned scheme. Some basic rules . wherever high speed links are involved, do not assume a certain price, single them out to allow an equal (to be recommended by LHCb) cost estimate of these links. Mention their length (which should be agreed upon with Frank Harris) and band-width. . Always base the price on procurement in 1999. . For components where a large price difference is expected in the future, supply a second price for expectations when bought in 2003. . wherever large scale integration in the FE is assumed, make it clear that the trigger electronics part of these FE boards is included in the trigger price.

3) Wherever the processing is asynchronous: show that the trigger will run up to a sustained luminosity of 5x10**32, or show the loss as a function of L. Typically some simulation of the asynchronous, or other "non-trivial" parts is expected. The baseline generator to provide the input will be decided soon (by the physics group), after which a new sample of MC will be generated.

4) The latency should be provided based on the above overall scheme and the simulation, in agreement with Ioana Videau.

5) Explain what is assumed for the FE synchronisation. How do you synchronise the FE data. How does your system deal with parts of your system (or the FE) having missed a clock, or suffers from single-event-upsets. How are these detected, how long to reset them, etc.. How is your system monitored/debugged. Yuri Ermolin has agreed to look into these items, and collect and compare the various scenarios.

6) If your solution restricts the algorithm as being implemented in SICB, provide the corresponding code to be able to check the physics consequences of these changes. Please check with the coordinators for muons (Renaud Le Gac) and calorimeters (Ivan Korolko) that they are aware of your special requirements, and that the performance of your algorithm is checked against noise/pile-up/background etc... in an identical way. All studies to be performed with the baseline generator as outlined above. We will have to fix a certain cal/muon lay-out, and cannot wait for "final" detector implementation decisions.

7) Suppose your implementation is chosen as the baseline solution: . what do you foresee to provide up to the TDR? . where does the manpower necessary (please make an estimate) come from to actually realize the trigger? Inversely if your solutions turns out not to be the preferred one: . what manpower could you provide for the chosen solution.

Since LHCb weeks are to crowded to allow in depth discussions, we plan to organise a few days of workshop in between LCHb week dedicated to the L0 implementation.

I wish you all a Merry Christmas and a Happy New Year.

Regards, Hans Dijkstra.

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