Trigger Requirements

1
Trigger Requirements

• first thoughts from
• Alessandro Di Mattia,
• Giovanni Siragusa,
• Sergio Grancagnolo,
• Andrea Ventura,
• Michela Biglietti,
• Diana Scannicchio
• John Baines,
• Dmitri Emelyianov,
• Iwona Grabowska-Bold,
• Alan Poppleton

LVL2 MS
long list to acknowledge people who reacted on
a very short notice
EF MS
ID trigger / PESA
LVL2 ID
EF ID
ID/Muon fitting in offline
2
ID requirements
Current map field size and access time OK for ID
algorithms in HLT At LVL2 the access time is
about 10 of the overall latency of the algorithm
BUT they would not like to see this increase.
Impact on performance of a similar size map,
less symmetric and less granular in B-filed steps
needs to be studied. Field / Pt precision gt
hard to quote an absolute number gt lets put it
in the other way ID HLT needs the best
resolution possible with a field map size
acceptable
3
EF

• Hardware baseline setup of EF
• 8 core PCs, 1GByte memory per core (upgradable
  to 2)
• 1 processing task (EF process) running per core
• ?1 GByte of memory available per process
• Recent Technical run
• exercise the HLT sw on pre-series of the final
  hardware
• measured 700 MBytes allocated by a single EF
  process (running EF for all slices single
  muon/electron/gamma/tau/etc trigger) using
  standard Athena Tools (i.e. magnetic field map
  and access tools)
• B-field of up to 100 MBytes (now 30MByte) are
  affordable and leave contingency for extra
  algorithms to be included in EF
• 1 GByte possible only on upgraded hardware
  (not foreseen at the moment)

4
EF Muon Spectrometer

• TrigMoore uses up to now- the offline
  iPatRecFitter (global Runge-Kutta based fit)
• Access to the field was optimized at some point
  on the available map step in most of the MS
  volume is 320 mm, sometimes 160, 80, 40 mm (3
  accesses per step to account for the local
  gradient) the optimization was based on the
  process of using a very low step size as starting
  condition and increasing it up to un-observable
  pt measurement degradation (both on average value
  and resolution)
• Depending on the region, a given step is chosen
• ? Without re-optimizing the access to the map
  (the step size in each region) the size of the
  magnetic field map does not impact on the number
  of accesses but just for the time of a single
  access takes
• ? Field look-ups are probably the timing
  bottleneck for the fit !
• ? MooMakeTracks (fit in TrigMoore based on
  iPatRec) takes more than 1/3 of the total
  TrigMoore time/event 400ms for single muons in
  nominal background conditions at high luminosity)
  1s EF total latency

5
From M.Biglietti and TrigMoore group talk at TP
week in May 2006 Muon EF performance
6
EF Muon Spectrometer

• TrigMoore performance
• Long study to see the effect of a coarse grained
  map used in EF reconstruction for a detailed
  (nominal) map in simulation or for data !
• The exercise just started with the following MS
  maps
• default map
• 40gaus step for MS only
• 80gaus step for MS only
• 80gaus step doubled step in phi and z (MS only)
• ?look at total timing of TrigMoore/track (not
  even isolating the fit !)
• no observable effects
• ?look at measured pt for 6 GeV and 20 GeV single
  muons (integrating in eta/phi !) granularity in
  phi-eta of the performance study would be
  necessary ? high statistics needed
• no observable effects

7
EF Muon Spectrometer
ptrec/pt 6 GeV sigma ptrec/pt 20 GeV sigma TrigMoore time/track
Def. Map 1.0040.002 4.1 0.2 1.0020.001 2.9 0.1 mean 79 rms 166
40 gaus step 1.0040.002 4.1 0.2 1.0010.001 3.0 0.1 mean 70 rms 158
80 gaus step 1.0060.002 4.3 0.3 1.0020.001 3.0 0.1 mean 83 rms 166
80 gaus step double step in phi/z 1.0080.002 3.8 0.2 1.0000.001 3.0 0.1 mean 72 rms 171