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Trigger region unit for the ALICE PHOS calorimeter
The Photon Spectrometer (PHOS) of ALICE measures electromagnetic showers of up to 100 GeV via a large matrix of PWO crystals, each read out by an APD. Trigger regions consist of 28*16 crystals, inter-connected via analogue signals generated on front-end cards and transmitted to Trigger Region Units...
Autores principales: | , , , , , , |
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Lenguaje: | eng |
Publicado: |
CERN
2005
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Materias: | |
Acceso en línea: | https://dx.doi.org/10.5170/CERN-2005-011.384 http://cds.cern.ch/record/929391 |
Sumario: | The Photon Spectrometer (PHOS) of ALICE measures electromagnetic showers of up to 100 GeV via a large matrix of PWO crystals, each read out by an APD. Trigger regions consist of 28*16 crystals, inter-connected via analogue signals generated on front-end cards and transmitted to Trigger Region Units (TRU) which digitize and process the analogue hit information. Eight TRU cards are embedded inside each PHOS module in water-cooled cassettes, each inserted between a block 14 FEE readout cards. Analogue sums are generated by fast summing shapers, with their outputs connected to the TRU via equal-length differential cables. The TRU receives analogue sums on 112 inputs and digitizes these via 12 bit ADCs which are inter-connected with a central FPGA via serial LVDS links. The level-0 and level-1 trigger algorithms are based on pipelined charge summing over 4 consecutive samples and over 4*4 crystal windows. Low latency level-0 decisions and more refined level-1 decisions are generated as a 40 MHz Yes/No sequence which is transmitted to the ALICE Central Trigger Processor. Reconfiguration logic allows detecting and correcting single event upsets even during trigger operation. |
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