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QuickSim- brief introduction -

Akiya MiyamotoKEK

22 June 2005

GLD meeting

http://www-jlc.kek.jp/subg/offl/lclib/notes/lclib-2000-1/index.html

See also

2A.Miyamoto , GLD meeting 22 June 2005

Components in QuickSim Beam pipe N layers of Vertex Detector M layers of Intermediate Tracker Materials between IT and central tracker Central tracker with L sampling EM Calorimeter in Barrel and End-Cap HD Calorimeter in Barrel and End-Cap

Location and sizes of these detectors are specified by input data card Tracker :

To get smeared track parameter, a equally-spaced ( N, L) sampling tracker with fixed r and z in solenoid is assumed. Multiple scattering in materials are considered. Energy loss is not considered For IT, only exact hits are saved

3A.Miyamoto , GLD meeting 22 June 2005

Procedure in QuickSim Start track

At beam pipe : modify track direction by multiple scattering At 1st vertex layer:

Estimate the number of vertex hits, then – modify track direction by multiple scattering– Calculate smeared VTX track parameter using the diagonalized error matrix if

number of VTX hits > 2. From 2nd vertex layer to the support tube ( CDC inner mat. )

Modify track momentum direction based on the effect of MS. Creates hit in IT, if it traverse IT.

At first meas. Layer of CDC Estimate the number of CDC hits. Calculate smeared CDC track parameter, using the diagonalized error matrix

Pivot of CDC track parameters are moved to 1st layer of VTX,where track parameters of CDC and VTX are averaged with weights given by the error matrixes.

Then pivot of track parameter is moved to IP.

4A.Miyamoto , GLD meeting 22 June 2005

Limitation of track smearing

Error matrix A term for measurement error

Cyclic trajectory Parabolic trajectory assuming high mom. Not good for low momentum tracks.

A term for multiple scattering MS effects in CDC for low momentum tracks

QuickSim resolution was about factor 2 smaller than the results of Geant3 simulation (JLC-I case).

5A.Miyamoto , GLD meeting 22 June 2005

Generation of Calorimeter signals

Tracks are extrapolated to Calorimeter and Generate signals in EM calorimeter, if e or Generate signals in HD calorimeter, if hadron No signals at all in calorimeter, if or

Calorimeter are segmented to small cells.Formula to define lateral spread.

Signals collected to the cell:

Energy deposit in each cells are smeared according to given resolution parameters.

1 2/ /1 2( ) exp expx b x bF x a a

_

_ ( ) ( )Cell area

Cell Signal F x F y dxdy

6A.Miyamoto , GLD meeting 22 June 2005

Parameters for lateral spread

Elemag Cal. Hadron Cal.

a1 0.055 0.088

b1 0.45 2.20

a2 0.396 0.044

b2 1.20 7.00

For hadron Calorimeter: Not compared with data yet!

7A.Miyamoto , GLD meeting 22 June 2005

Cal Clustering

Cal calorimeter: Clustering Algorithm Find highest energy counter BL1 whose energy larger than ETH.

Neighbor counter BL2 is included if E(BL2) > c1 x E(BL1)

Include BL3 which is neighbour to BL2, if E(BL3) < c2 x E(BL1) and E(BL3) < c3 x E(BL2)

Clustering parameters (Eth, c1, c2, c3) : Needs to be tuned to reconstruct single EM particle as single cluster double EM particles as double cluster

8A.Miyamoto , GLD meeting 22 June 2005

Typical EM tuning: example

Two photons are generated with 50mrad separation and efficiency to reconstruct as two clusters are studied as a function of parameters

9A.Miyamoto , GLD meeting 22 June 2005

Cal. –Track matching

Eg – Ec < n: 1-1 track-cluster match

Eg – Ec > n:Charged track + neutral

All connected cells are clustered into a global cluster.

If charged track touches a global cluster, total energy of cluster(Eg) and track energy of track(Ec) are compared.

Parameter, n, has to be tuned depending on processes.-- small n ghost neutral cluster-- large n less observed energy

http://www-jlc.kek.jp/subg/offl/lib/docs/cmbtrk/main.html

10A.Miyamoto , GLD meeting 22 June 2005

Dependance of n : ZH process

N=1.0Mh~117.6

N=3.0Mh~116.0

N=1.5Mh~116.8

N=2.5Mh~116.2

N=2.0Mh~116.3

Process: e+e- ZH X Observed particle masses are plotted.Input Mh=120GeV

11A.Miyamoto , GLD meeting 22 June 2005

Summary

In QuickSim, detector parameters can be modified by a input data card.

Correctness of parameters are not guaranteed. Comparison with performance studies by full simulator and parameter tuning are always necessary.

Yoshioka san and Fujikawa san are tuning QuickSim for a GLD configuration