******************************************************
* This macro allows the computation of the leak in   *
* the drift chamber.                                 *
* See http://www.slac.stanford.edu/BFROOT/www/Detector/CentralTracker/controls/gas/  *
* for an explanation for the calculation             * 
* Written by: Vincent Poireau (Sept 2004)            *
******************************************************

  ****
  * Do the initialisation, and ask for the time of the 
  * beginning and the end of the leak test
  ****

  * Some parameters
  opt fit
  set stat 10
  opt sta
  set fwid 5
  set fcol 2
  opt tic

  close 1
  h/file 1 leak.hbook

  n/plo 1.dprt9%time/60
  atitle 'Time (min)' 'DCH pressure'

  mess
  mess Please LOOK TO THE PLOT to enter the following values
  mess Time in minute when the leak test was *begun*?
  read beg
  mess Time in minute when the leak test was *ended*?
  read end

  ***
  * Do the fit, and give the leak rate
  ***
 
 * Profile for the pressure versus time
  prof 10 'Fit of the loss of pressure in the DCH' 50 [beg] [end] 0 1100 !
  n/plo 1.(log(dprt9))%time/60 [beg]<time/60<[end] ! ! ! n 10
  min 10 1
  max 10 2.0

  * Fit of the pressure
  v/cre par(2) R 1.8 -0.2e-3
  h/fit 10 p1 ! 2 par
  tau = -1/par(2)

  * Computation of the atmospheric pressure (averaged -> only one bin)
  prof 11 ! 1 [beg] [end] 0 1100 !
  n/plo 1.patm%time/60 [beg]<time/60<[end] ! ! ! n 11
  v/cre vpatm(1) R
  h/get_vect/content 11 vpatm

  * Computation of P0 (the pressure at initial time)
**  v/cre vLogDprt9(50) R
**  h/get_vect/content 10 vLogDprt9
**  p0 = vLogDprt9(1)
**  p0 = $SIGMA(exp([p0]))
* Finally we choose to compute the leak for a pressure of 4 mbars
  p0 = 4.

  * Final computation (5192 l is the volume of the chamber)
  leak = 0.63 * 5192 * [p0] / vpatm(1) / [tau]
  leak = $format([leak], F.3)

  * Produce a file with the plot
  for/file 66 leak.ps
  meta 66 -111
  title = Data from $env(day)
  title [title]
  h/plo 10
  atitle 'Time (min)' 'DCH pressure (log)'
  textX = [beg] + 0.05 * ([end] - [beg])
  text = Leak rate = [leak] l/min
  text [textX] 1.9 [text] 0.4
  close  66
  pi/print leak.gif

  mess
  mess (Tau from the fit = [tau] min)  
  mess *********************************************
  mess ** The leak rate at [p0] mbar is = [leak] l/min    
  mess *********************************************
  mess A leak.gif and leak.ps have been created