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Tpc drift velocity versus electric field

Updated on Mon, 2013-05-13 08:56. Originally created by fisyak on 2013-05-10 17:59.

 I am trying to match our Tpc drift velocity with Magboltz calculation. I see some contrudiction.
For Run XIII we see drift velocity 5.51 cm/us. Magboltz gives 5.5456 cm/us @ E = 133.37 V/cm

To check the drift velocity  dependence on electric field I have recalculated laser drift velocity for 

+--------------------+-------------+--------------+
| beginTime                     | cathode            | gatedGridRef      | run          E(V/cm)
+--------------------+-------------+--------------+
| 2004-01-12 14:26:44   | -27.95000076 | -115.00000000 | 5012033  133.37
| 2004-01-12 14:33:07   | -27.95000076 | -115.00000000 | 5012034   -"-  
| 2004-01-12 14:46:24   | -30.95000076 | -127.00000000 | 5012035  147.68
| 2004-01-12 14:50:29   | -30.95000076 | -127.00000000 | 5012036  -"-   
| 2004-01-12 15:02:23   | -24.95000076 | -103.00000000 | 5012037  119.05
| 2004-01-12 15:06:34   | -24.95000076 | -103.00000000 | 5012038  -"-   
| 2004-01-12 18:33:34   | -27.95000076 | -115.00000000 | 5012142  133.37
 

and put all of them on the same plot

The conclusions from these plots:
1. Run IV drift velocities is much close to Magboltz than Run XIII ones.
2. Maximum in measured and calculated drift velocity are shifted.
3. I have suspicion that CH4 content in Run XIII "P10" significantly low 10%


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