Changeset 3206 for trunk/MagicSoft/Mars


Ignore:
Timestamp:
02/16/04 17:31:56 (21 years ago)
Author:
gaug
Message:
*** empty log message ***
Location:
trunk/MagicSoft/Mars
Files:
2 edited

Legend:

Unmodified
Added
Removed
  • trunk/MagicSoft/Mars/Changelog

    r3205 r3206  
    55                                                 -*-*- END OF LINE -*-*-
    66 2004/02/16: Markus Gaug
     7
     8   * mcalib/MCalibrationPix.cc
     9     - documentation from David's email added
     10     - EffectiveQE decreased from 0.2 to 0.18 (see documentation)
    711
    812   * mcalib/Makefile, mcalib/CalibLinkDef.h:
  • trunk/MagicSoft/Mars/mcalib/MCalibrationPix.cc

    r3147 r3206  
    4040//   Error F-Factor = 0.02
    4141//
     42// - Average QE: (email David Paneque, 14.2.04):
     43//
     44//  The conversion factor that comes purely from QE folded to a Cherenkov
     45//  spectrum has to be multiplied by:
     46//  * Plexiglass window -->> 0.96 X 0.96
     47//  * PMT photoelectron collection efficiency -->> 0.9
     48//  * Light guides efficiency -->> 0.94
     49//
     50//  Concerning the light guides effiency estimation... Daniel Ferenc
     51//  is preparing some work (simulations) to estimate it. Yet so far, he has
     52//  been busy with other stuff, and this work is still UNfinished.
     53//
     54//  The estimation I did comes from:
     55//  1) Reflectivity of light guide walls is 85 % (aluminum)
     56//  2) At ZERO degree light incidence, 37% of the light hits such walls
     57//    (0.15X37%= 5.6% of light lost)
     58//  3) When increasing the light incidence angle, more and more light hits
     59//     the walls.
     60//
     61//  However, the loses due to larger amount of photons hitting the walls is more
     62//  or less counteracted by the fact that more and more photon trajectories cross
     63//  the PMT photocathode twice, increasing the effective sensitivity of the PMT.
     64//
     65//  Jurgen Gebauer did some quick measurements about this issue. I attach a
     66//  plot. You can see that the angular dependence is (more or less) in agreement
     67//  with a CosTheta function (below 20-25 degrees),
     68//  which is the variation of teh entrance window cross section. So, in
     69//  first approximation, no loses when increasing light incidence angle;
     70//  and therefore, the factor 0.94.
     71//
     72//  So, summarizing... I would propose the following conversion factors
     73//  (while working with CT1 cal box) in order to get the final number of photons
     74//  from the detected measured size in ADC counts.
     75//
     76//  Nph = ADC * FmethodConversionFactor * ConvPhe-PhFactor
     77//
     78//  FmethodConversionFactor ; measured for individual pmts
     79//
     80//  ConvPhe-PhFactor = 0.98 * 0.23 * 0.90 * 0.94 * 0.96 * 0.96 = 0.18
     81//
     82//  I would not apply any smearing of this factor (which we have in nature),
     83//  since we might be applying it to PMTs in the totally wrong direction.
     84//
     85//
    4286/////////////////////////////////////////////////////////////////////////////
    4387#include "MCalibrationPix.h"
     
    62106const Float_t MCalibrationPix::gkConvFFactorRelErrorLimit = 0.1;
    63107
    64 const Float_t MCalibrationPix::gkAverageQE                = 0.20;     
     108const Float_t MCalibrationPix::gkAverageQE                = 0.18;     
    65109const Float_t MCalibrationPix::gkAverageQEErr             = 0.02; 
    66110const Float_t MCalibrationPix::gkConversionHiLo           = 10.;
Note: See TracChangeset for help on using the changeset viewer.