HERA-B ECAL Trigger (fwd)
From: Ueli Straumann
Today I had the opportunity to visit the HERA-B ECAL and its trigger, where Marco Bruschi and his colleagues showed me the present status.
The HERA-B ECAl has about 6000 channels of Shashlik Calorimeter, about half of that is put mechanically together already in the hall (looks quite impressive!)
An initial system of about 200 channels of readout electronics (ADCs etc.) is connnected via a shark board acting as the link switch system to the readout. (The first full working chain of the HERA-B data acquisition system. This is an important milestone and relevant for us as well).
>From the ADC boards the data of each channel is transfered synchronously with 10 MHz (7+1 bit half - serially, representing the square root of energy) to the ECAL trigger board. This trigger board then receives the data and usese FPGAs (XILINX 4000s) and a set of lookup tables to find the clusters, and to do the HERA-B trigger algorithm. They also build the total energy of the inner 2000 channels. The board works at 40 MHz. One of this boards (9U, 10 layer) is presently connected and operating and delivering actual triggers to the readout system. This board is being able to find clusters centered at 50 different positions. The total system will consist of 120 such boards filling 9 9U VME crates.
The message system, which delivers the clusters to the track trigger as seeds was tested as well with a positive result.
Marco has studied the needs of LHC-B. He thinks the adaption of his HERA-B trigger system to LHC-B is relatively straight forward. (of course the input has to be changed to 40 MHz) He works on a note desribing this option and will present it in the trigger meeting of Oct 30 at CERN. So we will have the opportunity to discuss this interesting alternative together with the other options.
Thank you, Marco, very much for your work.
Many greetings Ueli Straumann
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