DAQ: comparison with an LHC experiment

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DAQ comparison with an LHC experiment

• J. Panman
• CERN
• VLVNT workshop 7 Oct 2003

Use as example CMS (slides taken from Cittolin's
talk at LHCC) Take numbers floating around this
week as typical performance needs
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Comparison of design parameters
Take numbers floating around this week as typical
performance needs For simplicity use a
digitized scenario (waveforms transmitted)
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Comparison of design parameters
Take numbers floating around this week as typical
performance needs For simplicity use a
digitized scenario (waveforms transmitted)
CMS
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Credits
slides taken from Cittolin's talk at LHCC
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Front end
Readout network
FE digitizer
Data from a string
Data from a string
DSP-like operation filter produces timecharge
from waveform assume 8 bytes to
encode (reduction x3)
200X PCI-X
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Network configurations
FED -gt FE digitizer
EVB staging by switch expansion
EVB staging by switch expansion
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CMS 2 stages Data to surface Readout Builder
Data to surface (rate decimation)
2 kByte
16 kByte
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CMS DAQ staging 2 RBs 25 kHz
Data to surface (rate decimation)
Readout Builders (modular staging)
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CMS DAQ staging 8 RBs 100 kHz
Data to surface (rate decimation)
Readout Builders (modular staging)
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CMS 3-D DAQ implementations and scaling
Data to surface Average event size 1 Mbyte No.
FED S-link64 ports 700 DAQ links (2.5 Gb/s)
512512 Event fragment size 2 kB FED builders
(8x8 dual) 64 Technology(2004) Myrinet
Readout Builders (x8) Lv-1 max. trigger
rate 12.5 kHz RU Builder (64x64) .125
Tbit/s Event fragment size 16 kB RU/BU
systems 64 Event filter power 105 SI95 EVB
technology (2006) Open
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Comparison of numbers
Total data rate of km3 detector similar to an LHC
detector after the L1 trigger Number of data
sources similar to number of FE
Digitizers Waveform filtering (if possible)
reduces the data volume by factor 3 Moore's law
will help by factor 4-8 compared to LHC Output
rate of HLT farm in km3 (presumably) much lower
than 100 Hzx1Mb Probably data storage problem
much smaller than LHC HLT processing time/byte
looks to be smaller than at LHC (LHC has to
reject real physics events)
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Summary
DAQ architecture of LHC experiments can be a
useful starting point for a design Similar
techniques, but probably smaller requirements A
couple of years later profit from
experience profit from performance/price ratio
trend At a first glance the DAQ does look
feasable