//==========================================
// Garfield V8.1 Input file for:  
//
// Vertical Drift Chamber (VDC) Simulation
// for the Qweak experiment at JLab
//
//==========================================
// 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: 04/02/2004
//==========================================

GLOBAL aiter      = 1000          // Loops for ARRIVAL-TIME-DISTRIBUTION
GLOBAL titer      = 40000         // Loops for TIMING

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


GLOBAL tofmin     = 0.0           // Minimal Time of Flight for histograms [us]
GLOBAL tofmax     = 0.3           // Minimal Time of Flight for histograms : 300ns

GLOBAL anode      = -4100         // high voltage on planes
GLOBAL wnum       = 41            // Number of wires
GLOBAL pitch      = 0.423         // perp. distance between signal wires   (4.23mm)

GLOBAL wdiameter  = 0.002         // 20um wire diameter
GLOBAL wpot       = 0.0           // voltage on signal wire = 0.0 V
GLOBAL wtension   = 70.0          // wire tention = 70g
GLOBAL wlength    = 25.0*1.141    // overall wire length (45deg) 


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

GLOBAL plane      =  1.3           // distance wire plane to HV plane (13mm)
GLOBAL wxpos      =  0.0           // all signal wires with x=0
GLOBAL wystart    =  -20*pitch     // position of first signal wire:  y=-8.46mm

GLOBAL anglemean  =  54.7          // mean garfield tracking angle = 54.7deg
GLOBAL anglemin   =  53.787        // min  garfield tracking angle = 53.787deg
GLOBAL anglemax   =  55.673        // max  garfield tracking angle = 55.673deg


// 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
//=============================================

// Load &CELL definition
 GET vdc_cell.dat

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

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

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

 // 1 atm 50/50 Argon-ethane mixture in your chamber.


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

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

// Plot some gas properties
// plot-options drift-velocity nodiffusion notownsend

 opt gas-plot nogas-print

//=============================================
& OPTIMISE
//=============================================

 //Prints the current potential settings
 DISPLAY

 //forces acting on a wire and the wire displacement
 SELECT 21
 FORCES  PRINT-SAG PLOT-SAG KEEP-SAG DETAILED ...
 ELECTROSTATICS GRAVITY


//=============================================
& FIELD
//=============================================

 AREA {-1.1*plane, -2*pitch, +1.1*plane, +2*pitch}

 // Plot electrical field 
 //track -1.3 0.0 -0.01 0.0
 //PLOT-FIELD GRAPH sqrt(EX**2+EY**2)

 //track * * -0.3 *
 //PLOT-FIELD GRAPH sqrt(EX**2+EY**2)

 //track -0.3 * -0.05 *
 //PLOT-FIELD GRAPH sqrt(EX**2+EY**2)

 //track -0.05 * -0.0001 *
 //PLOT-FIELD GRAPH sqrt(EX**2+EY**2)


 // Plot contour of Electrostatic potential
 //grid 25
 //area * -.423 * .423
 //PLOT-FIELD CONTOUR -V RANGE 1200 4000 n=14

 //area -.423 * .423 *
 //PLOT-FIELD CONTOUR -V RANGE  900 2100 n=24

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

 //Sets the size and view of the drift area

 AREA {-1.1*plane, -3.0*pitch, +1.1*plane, +3.0*pitch}
 
 //Number of drift lines used by x(t) etc.
 LINES 60

 //Grid density for tables and contour plots
 GRID 10 20

 // define area around wire #21 for possible plots
 SELECT 21                   // select center wire
 
 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 0.85 GeV  

//======================== 
// drift line calculation: 
//======================== 

//---------------------
// Open Postscript file
//---------------------
!add meta type PostScript file-name "erin_track.ps"
!open meta
!act meta


// First define a track
  TRACK  {-1.1*plane, -1.1*plane, +1.1*plane, +1.1*plane}

 // will begin at some of the boundaries of the drift area as set by AREA.
 //DRIFT EDGE notleft notright up down isochrone 0.020

 // drift line calculation: 
 // electrons or ions start to drift from the surfaces of the wires that 
 // have been SELECTed.
 //DRIFT WIRE lines 30 isochrone 0.020

 // drift line calculation:  will begin on the track.
 DRIFT TRACK TIME-GRAPH CONTOUR 0.020

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