//==========================================
// Garfield V8.1 Input file for:  
//
// Vertical Drift Chamber (VDC) Simulation
// for the Qweak experiment at JLab
//
// => Simulation of a wire signal given by SIGNAL
//
//================================================================
// Simplified VDC layout for Garfield
//
// VDC consists of one wire plane and two HV planes.
// Garfield forces us to use this orientation of the VDC since 
// in Garfiled  you can only define a X-RANGE **only** for a XT-PLOT ... 
// (There is no YT-PLOT defined in Garfield)
//
//     |     | / 
//     |  *  |/
//     |     |            |
//     |  * /|          Y |
//     |   / |            |
//     |  *  |            ------> X
//     | /   |        used coordinate system
//     |/ *  |
//     |     |          ------> Gravity vector
//    /|  *  |
//   / |     |
//  /  |  *  |
//
//=================================================================
// 
// 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 tofmin     = 0.0           // Minimal Time of Flight for histograms [us]
GLOBAL tofmax     = 0.3           // Minimal Time of Flight for histograms : 300ns

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

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

Global gas_file     `Arg-50-Eth-50.gas`
Global gas_member   `a50e50`


// Delete some result files, otherwise results from different settings/simulations
// will be saved in the same file ...   


//=============================================
& 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 existing gas_file, which contains all
// the gas properties needed for tracking
   GET {gas_file,gas_member}

// Prepares cluster generation by Heed
   HEED argon 50 ethane 50

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

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

// to be explained ... 
 INTEGRATION-PARAMETERS COMPUTE-IF-INTERPOLATION-FAILS


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

//=============================================
& SIGNAL
//=============================================

// Before issuing a SIGNAL instruction, one has to
//
//    * set the time WINDOW over which signals are to be computed;
//    * SELECT the electrodes to be read out. 
//    * set both the geometrical parameters and the clustering model of the TRACK;
//    * set the AVALANCHE model;


 //Sets the size and view of the drift area
 AREA {-1.1*plane, -1.0*tpitch, +1.1*plane, +1.0*tpitch}

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

 // 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 1.1 GeV  


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


// AVALANCE:
// Chooses the probability distribution to be used for the avalanche multiplication factor, 
// i.e. the number of electrons produced in the avalanche + the electron that started the 
// avalanche. Electrons that are lost in attachment processes before reaching an electrode 
// are included in the count. A multiplication factor of 1 means that there is no multiplication, 
// factors smaller than 1 do not occur.
//
// No default type of avalanche is set !!!
// you must issue an AVALANCHE command prior to any signal calculation !!!
//
AVALANCHE ...
   TOWNSEND


//Setting the time WINDOW over which signals are to be computed: \
// WINDOW t_start t_step  [n_step]
//By default, signals start at t=0 and are sampled every 0.01 microsec. 
//The number of samples is by default MXLIST, usually 200 or 1000 depending on 
//the compilation flags that were selected.
//
WINDOW 0.0 0.01 200


SIGNAL ...
   AVALANCHE  ...
   SAMPLE-SIGNAL ...
   DIFFUSION ...
   ELECTRON-PULSE ...
   NOION-PULSE ...
   MONTE-CARLO-DRIFT-LINES ...
   NEW ...
   NOCROSS-INDUCED ...
   NOINTERPOLATE-TRACK 

// Plots the signals
PLOT-SIGNALS ...
   TIME-WINDOW 0.0 0.3 ...
   RANGE  AUTOMATIC  ...
   WIRES S21 ...
   NOCROSS-INDUCED-SIGNALS ...
   DIRECT-SIGNALS 


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