//==========================================
// Garfield V8.1 Input file for:  
//
// Vertical Drift Chamber (VDC) Simulation
// for the Qweak experiment at JLab
//
// => Simulation of the XT-Plot
//    Correlation between perp. track distance to the wire plane and
//    the drift time of the first electron hitting the selected wire 
//
//==========================================
// VDC Realization in Garfield:
//
// VDC consists of one wire plane and two HV planes
// 
//==========================================
// 
// Author: Klaus Grimm
//         Department of Physics
//         The College of William and Mary
//         Williamsburg, VA 23185 
//
//  email: grimm@jlab.org
//
//==========================================
// Last Change: 05/02/2004
//==========================================


GLOBAL tanglemin   = 45.0
GLOBAL tanglemax   = 65.0
GLOBAL tanglestep  =  2.0

GLOBAL xstep       =  0.05        // Stepping size in X for tracks (0.05=500um)

GLOBAL plane      =  1.3           // distance wire plane to HV plane (13mm)
GLOBAL pitch      =  0.423         // perp. distance between signal wires   (4.23mm)
GLOBAL apitch     =  0.423*0.5     // half top   pitch size used for ARRIVAL-TIME-DISTRIBUTION
GLOBAL tpitch     =  apitch*1.41   // bit more than bottom half pitch size used for TIMING

// Specify the gas-file to be loaded
Global gas_file     `Ar-C2H6_50-50.gas`
//Global gas_file     `Ar-C2H6_63-37.gas`
//Global gas_file     `Ar-CO2_90-10.gas`


//=============================================
& CELL
//=============================================

// Read &CELL definition
 GET vdc_cell.dat

// Gravity points perp. to HV plane = x directection
 GRAVITY  1 0 0

//=============================================
& MAGNETIC
//=============================================

 // at present: no B fieed here
 // whats about the earth B field ?!
 COMPONENTS 0 0 0 GAUSS

//=============================================
& GAS
//=============================================

 // Load existing gas_file, which contains all
 // the gas properties needed for tracking

Call inquire_file(gas_file,exist)
 
If exist Then
   get {gas_file}
 Else
 Say "Gas file doesn't exist, please check"
Endif

//=============================================
& DRIFT
//=============================================

 INTEGRATION-PARAMETERS COMPUTE-IF-INTERPOLATION-FAILS
 
 // Heed takes care of cluster generation, it simulates the ionisation of 
 // the gas molecules by a particle.
 TRACK HEED ...
   NODELTA-ELECTRONS NOTRACE-DELTA-ELECTRONS ... 
   NOMULTIPLE-SCATTERING ...
   NOENERGY-CUT ELECTRON ENERGY 1.165 GeV  

 //Sets the size and view of the drift area
 AREA {-1.1*plane, -1.0*tpitch, +1.1*plane, +1.0*tpitch}
 
 //Number of drift lines used by x(t) etc.
 LINES 100

 // define area around wire #21 for possible plots
 SELECT 21                   // select center wire
 
//---------------------
// Open Postscript file
//---------------------
!add meta type PostScript file-name "xt.ps"
!open meta
!act meta


FOR tangle from {tanglemin} to {tanglemax} STEP {tanglestep} DO

// delete old entries from previous simulations
* %DELETE "XT_{angle}deg_S21.dat" .

// XT-PLOT: relation between the perp. position of a track and the drift time.
// This is a calibration curve used by the track reconstruction program

Say "Simulating now XT-PLOT for incident angle = {tangle}"

  XT-PLOT ...
    ANGLE {tangle} ...
    X-RANGE {0.0 , 1.1*plane}  X-STEP {xstep} ...
    PRECISION 1E-4 ...
    PLOT-XT-RELATION ...
    DATASET "XT_{tangle}deg_S21.dat" 

ENDDO

//----------------------
// Close Postscript file
//----------------------
!deact meta
!close meta
!del   meta