Документ взят из кэша поисковой машины. Адрес оригинального документа : http://zebu.uoregon.edu/~uochep/talks/talks01/Root2001.pdf
Дата изменения: Wed Sep 5 02:41:41 2001
Дата индексирования: Tue Oct 2 10:50:13 2012
Кодировка:
Root at the LCD
6/13/2001 M. Iwasaki Univ. of Oregon


North American Linear Collider Detector Group (LCD) has constructed a simulation facility based on Root Ю LCD Root

So far we only support Linux and SunOS (developing Windows)


Event generation at LCD Root
· PANDORA-PYTHIA (C++) by M.Peskin Ю our main generator include beam polarization, beamstrahlung CINT implementation directly use in C++ interpreter · PYTHIA (TPYTHIA: supported by ROOT) Output : ROOT or stdHEP (HEPEVT common) ROOT can go through FastMC stdHEP can go through FullMC (GISMO) & FastMC Or can be directly linked to FastMC


Detector Simulation at LCD Root
We use 2 kinds of detector simulations · Fast simulation For physics studies · Full simulation For detector studies Fast simulation Smear particle position/energy and IP position Output Root or is directly linked to Event Analysis Full simulation (GISMO) make digitized detector outputs (SIO binary) Full recon make tracks and clusters Output Root or is directly linked to Event Analysis


Detector Simulation at LCD Root
LCD Group considering 3 kinds of Detector designs Silicon, Large, and Precise Ю Different Detector sizes, materials, and Calorimeter Configurations.... Coil HAD HAD OR Coil EM EM ... We prepare 3 kinds of Detector geometry files Detector resolution files (for smearing) Some/all of these parameters can also be changed at user analysis level


Event Analysis at LCD Root
We have several useful analysis tools for Linear Collider experiments ·Jet Finder ... 3 kinds of algorithms ·Thrust Finder ·Particle extrapolator ·Topological Vertexing ... translated from SLD ZVTOP


Jet Finder
3 kinds of algorithms .. Jade, Jade E, and Durham Comparison of original Fortran Jet Finder and ours Fortran LCD Root (C++)
200 180 160 140 120 100 80 60 40 20 0 0 200 180 160 140 120 100 80 60 40 20 0 0

1

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

8

9

10

(tt 6jets event) # of Jets

# of Jets

Works well!


Thrust Finder
tt events events

Works well!


Topological vertex finder Translated from SLD ZVTOP Reconstruct secondary vertices in a jet .. Find points of high overlap tracks
cЮD D primary
10000 8000

bЮBЮD D B primary

uds

1400 1200 1000

c

2000 1800 1600 1400 1200

b

6000 800

1000 4000 600 400 2000 200 0 0 0 0 800 600 400 200 1 2 3 4 5 6 7 8 9 10 0 0 1 2 3 4 5 6 7 8 9 10

1

2

3

4

5

6

7

8

9

10

#Ver tices reconstructed


Using the reconstructed vertices, we can do 1) Heavy-flavor tagging
450 400 350 300 250 200
400 600

2) Charge separation
1000

bottom charm uds

BB+ B0

800

150 100 50 0 0 1 2 3 4 5 6 7
0 -4 -3 -2 -1 0 1 Vertex Charge 2 3 4 200

PT corrected Ver tex Mass (GeV)

Vertex Mass

Vertex Charge

For example..


Analysis example with b-tag:
Reconstruction of t-quark mass in tt 6jets event Without b-tag
1400 1200 1000 800 300 600 200 400 200 0 100 100 0 100 600 500 400

With b-tag

Signal BG
120 140 160 180 200 220 240 260

120

140

160

180

200

220

240

260

Mass (GeV/c2)

Mass (GeV/c2)

(FastMC)


LCD Root Event Display

FastMC (e+e- Ю ZH)


LCD Root Event Display

FullMC (e+e- Ю tt)


Event structure at LCD Root
Event Event Header event number ... McParticles Beam parameters polarization, IP position ... Generator level particle information Raw data (Full) Reconstructed Data Tracks Clusters Based on TClonesArray VXDHits TrackerHits CalHits


Summary
LCD group has constructed simulation/analysis tools for the future Linear Collider experiments ·The simulation/analysis tools based on ROOT ·LCD Root handles several I/O ... Some of them require STL (can be worked ROOT V3.00 or later) Ю work well!

·There is a LCD Root tutorial page! (Under construction) URL: http://www-sldnt.slac.stanford.edu/nld/New/Docs /LCD_Root/root.htm


Future Plan
· GEANT4 · GUI · Support Windows We are happy to collaborate with other exp. groups to develop analysis tools!! ( Currently LCD Root is maintained by 2 people ... )