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Ok Re: Problem with local time after wavelength shifting 

Forum: Processes Involving Optical Photons
Re: Question Problem with local time after wavelength shifting (Volodymyr Rodin)
Date: 02 Jun, 2017
From: Volodymyr Rodin <Volodymyr Rodin>

Hello, everyone.

With Peter's help, we have found the cause of this issue.

Some example of Local time(ns) distribution with this problem: Local time error.png

One can see narrow peak near zero.

With /tracking/verbose 1 command last steps of photons from that peak were seemed in the following manner:

Local time: 0 ns
 Global time: 0.580488 ns
12466   1.76 mm   2.99 cm   7.39 cm   2.95 eV      0 eV      0 fm   67.7 cm     WOM tube  Transportation
 Local time: 0 ns
 Global time: 0.580488 ns
12467   1.66 mm      3 cm    7.4 cm   2.95 eV      0 eV    109 um   67.7 cm         WLS1  Transportation
 Local time: 0 ns
 Global time: 0.580488 ns
12468   1.66 mm      3 cm    7.4 cm   2.95 eV      0 eV      0 fm   67.7 cm     Air_gap1  Transportation
 Local time: 0 ns
 Global time: 0.580488 ns
12469   1.62 mm      3 cm    7.4 cm   2.95 eV      0 eV   48.7 um   67.7 cm         WLS1  Transportation
 Local time: 0 ns
 Global time: 0.580488 ns
12470  -5.28 mm   2.89 cm   7.65 cm   2.95 eV      0 eV   7.41 mm   68.4 cm    PMMA_Ring  Transportation
 Local time: 0.0380418 ns
 Global time: 0.61853 ns
12471  -11.1 cm   1.33 cm   11.8 cm   2.95 eV      0 eV   11.4 cm   79.9 cm   ScintilatorBoxPV  Transportation
 Local time: 0.622637 ns
 Global time: 1.20313 ns

The cause of such strange Local time output was the wrong sequence of refractive indexes for WLS1 material:

  Wrong: G4double rindexWLS[5] = { 1.52, 1.515 , 1.505 , 1.504 , 1.5 };
  Correct: G4double rindexWLS[5] = { 1.5, 1.504 , 1.505 , 1.515 , 1.52 };
G4double ppckovEmit[5] = { 2.95 * eV, 3.0401*eV , 3.0402*eV , 3.5403*eV , 3.8404*eV};

Correct time distribution: Local time correct.png

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/06/02/01.17-34819-Local_time_error.png
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/06/02/01.17-8521-Local_time_correct.png

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