View source for Left HRS VDC T0 Drifts

For the fifth pass production data, we can split the runs into three periods: <br>

<pre>
Period I:   November 8 to November 11,  runs: (3036-3203) 
Period II:  November 12 to November 13, runs: (3304-3323) 
Period III: November 16 to present,     runs: (3528-present) 
</pre>

During Period I, the T3 delay at the BigBite Weldment was set to 60 ns. <br>
There is a short period of time, when the delay was 76 ns (runs 3117-3124). <br>
None of these runs are production.

For Period II, all the T3 delay was removed and the T1 delay was changed <br>
to move the coincidence peak into the middle of the window.

Period III began after the 2.5 day down due to the CHL problem. As far as we <br>
know, there were no timing changes between Period II and III, however, re-timing <br>
was set up for the BigBite triggers. 

[[Image:drift.gif|700px]]

See Halog entry for further details on this figure:

[http://www.jlab.org/~adaq/halog/html/0811_archive/081118104840.html Study of VDC T0 Drift in HALOG]

==The First Period Up Close==

The next figure shows Period I including runs at the beginning of this production <br>
period and also all the runs when the gas system shut down on November 9, 2008.  From <br>
this analysis, the '''affected runs are 3106 through 3112'''.  The U1 and U2 planes are defintely <br>
more problematic than the V1 and V2 planes.  Prior to the gas problem, there is clear evidence <br> 
that the T0's were drifting to smaller values by a few ns over a period of a day or so.

Starting with run 3125, after the VDC's had recovered, the time offsets appear to stabilize until <br>
we stopped production on the morning of November 11th.

[[Image:drift_pedI.gif]]

'''Here are the run numbers used in the Period I figure''':

<pre>
Plot Run      Actual Run Number
--------------------------------
 0                  3029
 1                  3041
 2                  3047
 3                  3056
 4                  3061
 5                  3074
 6                  3083
 7                  3096
 8                  3097
 9                  3100
10                  3105
11                  3106
12                  3107
13                  3108
14                  3109
15                  3110
16                  3111
17                  3112
18                  3125
19                  3151
20                  3164
21                  3181
22                  3192
23                  3201
</pre>