LCD simulation software efforts at NIU

Dhiman Chakrabortydhiman@fnal.gov

Northern Illinois University (NIU)/ Northern Illinois Center for Accelerator

and Detector Development (NICADD)

http://nicadd.niu.edu/

ALCPG workshopU. Of Texas, Arlington, 09-11 Jan, 2003

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

2

LC detector simulation software: work in progress

– Transition from GISMO to GEANT4,– Modular, flexible design towards a universal

package • Standardize interfaces to offer the best of all

implementations currently available for – detector geometry description – input data (event generator output)– detector simulator output

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

3

The LCDG4 detector simulation package

(M. Arov, R. McIntosh, V. Zutshi, D. Chakraborty, NIU/NICADD)• A GEANT4-based simulation program

– Not tied to any specific platform (ROOT/JAS/PAW)

• XML description of detector geometry– Needs structural improvements for better generality

• Reads input data in STDHep format• SIO/ROOT/ASCII output

– S(erial)IO compatible with JAS-based analysis code– LCDG4 can write and JAS can read ROOT files

• Beta release imminent – 2 known problems fixed during the NIU workshop

• The plan is to merge LCDG4 and MOKKA into a single package that combines the best of both.

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

4

Decoupling the simulator from Root

• LCDG4 is adapted from LCDRoot (M. Iwasaki, T. Abe),

• Root internal classes replaced by STL, CLHEP,

• Now a standalone simulation program, not tied to any other application/analysis environment,

• I/O compatible with the SLAC/HEP.LCD library & JAS,

• Root output capability is preserved as an option.

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

5

O rg an iza tio n o f L CD G 4 p a cka geC la sse s m arke d in g ree n a re n e w o r rew ritten

HADCallorimeterEM Callorimeter

TrackerVXD etc.

XYZtoID classInitialization

Required for futureSpecialization of the detector

XML2G4DetConstExtracts the info

about the dimmentions ofthe detector

SIO record constructor

Primary Detector Construction

STDHEP inputUnder construction

PrimaryGeneratorActionMain Physics content

XYZtoID convertionProdices the HitID

HAD HitsEM HitsMU Hits

etc.

SIO record fillThe final output stream

EventAction TrackerActionStepingAction

(MCpart Mannager)

LCDG4The Main Driver

XML parserReads in the detector description

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

6

Advantages of the SIO format

• (sequential) access to very large files without overburdening memory,

• Allows simultaneous writing to multiple streams,

• Has built-in file compression, which is important in view of large event sizes.

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

7

Non-projective and non-rectangular cell geometries (in

the digitizer)• Gismo-based simulator only allows

towers of constant (Δθ,Δφ),• An entirely projective tower design is not

optimal for an E-flow calorimeter,– (r,θ) range is too large for uniform scaling.

• Particular non-projective and non-rectangular geometries have been simulated in LCDG4 although more work is needed to make it more general and flexible,

• Projective rectangular geometries are supported just as in Gismo.

(0,0)

(0,2)

(1,1)

(1,-1)(-1,-1)

(-1,1)

(j,k)

Z(k)

φ(j)

(0,-2)

Layer (i)

Cell (j, k)

The Cell “neighborhood”

NIU Prototype

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

9

Preliminary test results

• Sampling fractions:

• Passes “order-of-magnitude” sanity check, but perhaps not quite correct - being checked for bugs.

Simulator EM frac Had frac

Gismo 0.02187 0.06338

LCDG4 0.05936 0.07421

Total (EM+HAD) energy: 10 GeV π+

Using LCDG4 with NICADD-designed detector

Energy, GeV

0 2 4 6 8 10 12 14 160

20

40

60

80

100

120

140 entries : 1001.0 min : 0 max : 16.318 mean : 9.9900 rms : 1.8152

Energy, GeV

1 2 3 4 5 6 7 8 9 10 11 12 13 14 1505

101520253035404550

Total HAD energy: 20 GeV π+

number of hits in 1000s

Energy, GeV

0 5 10 15 20 25 30 35

2468

1012141618

Measured energy vs nhits in HCal: 20 GeV π+

Shape ok, but horizontal scale is ~7x Gismo!

Hcal longitudinal shower profile of 10 GeV π+

Total energy measured in Hcal: 10 GeV π+ (1000 events)

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

15

SIO file contents

• Event header• Ecal hit list• Hcal hit list• Tracker and muon info• MC particle table

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

16

How to check it out

• http://nicadd.niu.edu/simulations/software/

• Source + binary (Linux) are available• lcdg4-bin,tar.gz and materials.tar.gz• the shell command is > lcdg4 b input_file.xml output_file.sio Detector_ID MacroFile HepEvt_File

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

17

Known problems, things to do …

• Primaries absent from the MC particle table– Cause found, figuring out fundamental changes in

container structures which will optimize speed will also cure this problem.

• Too many hits, excess energy may be due to overcounting (?), the above procedure should fix this as well.

• Geometry is hard-coded in the non-projective version. Need to combine with the projective version, make it more general and flexible.

• Some more “integration”/packaging needed.

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

18

Detector representation issuesGoals

• portability – easy exchange of detector models

• flexibility -- easy changes in detector configuration

• uniformity (universality) in detector description for

comparisons and cross checks across detectors.

• …

Driver + API-handler layer

GUI editor

GeometryDatabase(mySQL?)

User

Det. Sim. Reconstruction Analysis

API API API

API

ALCPG workshop, UTA, 09-jan-03

Simulation efforts at NIU Dhiman Chakraborty

19

Summary and plans• A stand-alone simulation program based on GEANT4

is ready for testing. • Order events online at http://nicadd.niu.edu/• Has all the capabilities of Gismo, plus some more.• A few problems – being fixed.• Emphasis on the need for global integration –

working with SLAC, CALICE, to combine the best of Mokka and LCDG4 into one simulation package.

• Figuring out the recipe for detector geometry description is a major challenge ahead.

• Start with a lightweight, flexible, functioning system.• Documentation: manuals, tutorials, FAQs, … • It’s a major undertaking – collaborator(s) wanted.