Simulating SiD for the LOI

Norman Graf (SLAC)

SiD Phone Meeting

July 30, 2008

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LOI Detector Simulations Need to clarify exactly what is required for the LOI

and what is deferred to the CDR/TDR. To-date the philosophy has been to provide a very

flexible framework which would allow a number of detectors to be designed and studied very quickly.

Answer the “big picture” questions first where the details do not matter, then only spend time and effort to study the engineering details on a roughly optimal design.

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Detectors under investigationacme0605

acme0605_1cmecalacme0605_30layerecalacme0605_40layerecalacme0605_ecal150acme0605_ecal150_4Tacme0605_ecal150_steel_rpcacme0605_ecal150_steel_scintacme0605_ecal150_w_rpcacme0605_ecal175acme0605_ecal175_3Tacme0605_ecal175_4Tacme0605_ecal175_steel_rpcacme0605_ecal175_steel_scintacme0605_ecal175_w_rpcacme0605_steel_rpcacme0605_steel_scintacme0605_w_rpcacme0703_cu_rpcacme0703_cu_scintacme0703_pb_rpcacme0703_pb_scint

apex0705_r125_steel1.5_scintapex0705_r125_steel2.5_scintapex0705_r125_steel_scintapex0705_r125_steel_scint_3x3hcalapex0705_r125_w_scintapex0705_r150_steel_scintapex0705_r150_steel_scint_4Tapex0705_r175_steel_scintapex0705_r175_steel_scint_3x3hcalapex0705_r175_steel_scint_4Tapex0705_r175_steel_scint_4T_3x3hcalapex0705_r200_steel_scintapex0705_r200_steel_scint_4Tapex0705_r225_steel_scintapex0705_r225_steel_scint_3x3hcalapex0705_r225_steel_scint_3Tapex0705_r225_steel_scint_4Tsid01sid01_scintsid01_scint_3x3hcalsid01_polyhedra

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sid01 The current model of the Silicon Detector is,

therefore, quite simple, consisting of cylindrical barrel geometries and disks in the forward region.

A lot of effort has gone into ensuring that the correct amount and distribution of material is included, but there are no cracks, gaps or overlaps.

The detector description can be found at:

http://confluence.slac.stanford.edu/display/ilc/sid01

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Improved Simulations Having settled on a concept with the requisite

performance, will have to design a detector which can be built.

Engineering will have to be done to come up with the plans, but the existing simulation package can already handle arbitrarily complex shapes.

Can then study effects of support material, dead regions due to stay-clears, readout, power supplies, etc.

However, hard work is in reconstructing and analyzing this, not simulating it.

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More complex geometries Arbitrarily complex geometries can be accommodated

in the lcdd detector description, but these will not be propagated to the reconstruction system. May be appropriate for supports, readouts, and far-forward

BDS/MDI elements. CAD to GEANT functionality implemented, and

tested for simple elements, so engineering drawings for some elements can be adopted ~as-is. e.g. BDS elements, beampipe, etc.

Will, of course, have an impact on performance due to use of BREPS in Geant.

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sid01_polyhedraDodecagonal,

overlapping stave EMCal

Dodecagonal, wedge HCal

Octagonal, wedge Muon

Cylindrical Solenoid with substructure

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Complex Geometry & Reconstruction Propose that we continue with simplified geometries for the time being.

For those detectors for which more detailed engineering designs become available, can compare performance using subdetector metrics such as tracking efficiency, resolution, etc.

If time permits, can entertain the possibility of running benchmark events through improved detector designs.

Reconstruction code should aim to be robust against such changes.

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Defining the Detector(s) for the LOI As the detectors become more realistic, and therefore more complex, more interaction is needed between subdetector experts and the simulation group.

The sim/reco group provides the tools to define detectors, but it is the responsibility of the detector subgroups to ensure that their design is being correctly simulated.

Can we find someone to take on the responsibility to lead the optimization process?

Need to establish a Change Control Board for THE Silicon Detector.

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Defining sid02 Decide what needs to change from the current

baseline sid01.1. What are the “global” parameters? Can we decide?

2. How do subsystems change in reaction to this? e.g. how to interpret “make HCal 4.5 deep”

simply add more baseline layers of 2cm SS + 8mm RPC? or change absorber layer thickness as well?

e.g. “extend z of tracker volume to 2.1m” simply stretch existing tracker barrels? keep barrels and add extra disks? add extra support/readout material?

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sid01 sid02 Should be able to adiabatically update sid01 design. sid01 beamcal designed for 2mr, need to change to

reflect 14mr design. Colorado group has started this, needs to be checked

Beampipe design needs to be agreed upon. If we stretch the tracker and increase coil radius, will

need new field map. Does SiD want DID or anti-DID?

Will vertex detector stay the same? Tracking group needs to decide on changes to outer

tracker.

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sid01 sid02 Assume EM calorimeter stays the same, just extend

barrel. Is there any desire to improve the energy resolution?

HCal group needs to decide how to make HCal deeper.

How does Solenoid change? Muon system currently has 48 instrumented layers.

How does this change?

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Detector characterization For each detector, run neutral single particles to determine

calorimeter sampling fractions: n,n,K0

L, gamma, 10k events per run E = 1, 2, 5, 10, 20, 50, 100 GeV = 90, 100, 110, 120, 130, 140, 150, 160, 170

Single charged particles for tracking characterization and calorimeter shower/track association +/-, +/-, p, K+/-

Composite single particles: 0, , , , K0S,, etc.

Single quarks (u,d,s) and Z0(uds) at fixed angles and energies

Dijet (uds) events at 100, 200, 500, 1000 GeV cms ZZ(qqνν and qqqq), ZZνν, WWνν, Zh(qqqq, qq,

qq), ttbar, etc. Web accessible http://www.lcsim.org/datasets/ftp.html

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slic performance @ 500GeV cms

Process     #jets     s/event   

qqbar         2   48  

ZZ (qq νν) 2 22

ZZ (qq qq)     4   52      

ttbar         6   56      

Full SM ? 28

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Next Steps for LOI SM Data Sample 500GeV sample done.

Have generated e+e- beam interactions at 250 GeV using GuineaPig. Provides pair background events and beam spectra for event

generation. Will soon start to produce full SM data set at 250

GeV. Need to identify exactly which files constitute the

benchmark “signal” samples. Need to identify which subset of the SM sample

defines the backgrounds.

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LOI Performance Metrics Although a set of benchmark processes has been

identified for the LOI, the exact metrics for performance characterization have not been explicitly stated.

The backgrounds to be considered, both physics and machine-related, were also never explicitly laid out.

WWS Software Panel was disbanded at the ECFA-LC meeting in Warsaw, so not clear to whom this task now falls.

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Beam Background Overlays

• Take output from full beam simulation (from IR/backgrounds group)

• Feed into full detector simulation• Build library of simulated background bunches• Overlay backgrounds on signal events at start of

reconstruction• Adjust timing of hits (for TPC e.g.)• Add energy in calorimeter cells

• Allows to change #bunches/train, bunch timing• What does SiD assume for event integration?

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Event Processing & Reconstruction Have not explicitly discussed simulating the response of sid02 to the benchmark & background samples. Computing requirements not yet clarified

Which events? How many? Computing resources at SLAC not guaranteed. Facing “perfect storm” of BaBar reprocessing, ATLAS MC

production at 10TeV, and GLAST data & MC processing. Exploring use of grid resources at FNAL.

No discussion of reconstruction. Do not yet have production reconstruction, no idea of

computing requirements. No discussion of analysis

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Summary An enormous amount of work still needs to be done just to

define what the silicon detector is for the purposes of the LOI. Subsystem leaders need to make sure that their detectors are

defined correctly and that the detector being simulated in the MC bears some resemblance to that being described in the rest of the LOI. Detector needs to be debugged & characterized (e.g. sampling fractions)

Event samples at 250 GeV cms need to be generated. Explicit background samples need to be identified. Benchmark measurables need to be defined. Events need to be processed through the simulation. Events need to be processed through the reconstruction. Analyses have to be developed.