From: Radoslaw Karabowicz (radziu@zefir.if.uj.edu.pl)
Date: Fri Mar 07 2003 - 14:30:04 EST
As you have probably noticed we experienced some problems with the drift
chambers, which arose from confusion with HV suppliers and the TDCs.
Nowadays things seem to look brighter, thanks to the help of the
on-site people at BNL. In order to convince you of good performance
of the DCs below is a short collection of the track parameters from
several d-Au runs. As you can see, the achieved resolution in all
of the detectors (113-138 microns) looks very reasonable (just to remind
you the required track resolution suggested in the BRAHMS design report
was 300 microns).
Recent repairs to the T3's high voltage supply module and one of the TDCs
result in far better performance of this detector - please compare the
improvement in run#8221 as compared to #8061 and #8217 in the track
resolution (137.9->118.9->115.9) and the average number of hits per
track (21.5->21.7->22.9). Furthermore, the ratio of T3 to T4 numbers
of tracks looks better in run 8221 (i.e. it is greater than one, which is
what we would expect).
Here is the table (legend:
detector ID | RESOLUTION[microns] | HITS PER TRACK | number of tracks):
run# 8061
T3 | 137.9 | 21.5 | 750
T4 | 113.2 | 23.4 | 1064
T5 | 134.4 | 18.5 | 660
run# 8217
T3 | 118.9 | 21.7 | 273
T4 | 123.4 | 23.3 | 311
T5 | 127.6 | 21.6 | 213
run# 8221
T3 | 115.9 | 22.9 | 3008
T4 | 121.4 | 23.3 | 2150
T5 | 127.2 | 21.7 | 1201
where:
8061 FFS: angle: 12.00, D1: 843/B, D2: 690/B
BFS: angle: 12.00, D3: 730/B, D4: 671/B
8217 FFS: angle: 4.00, D1: 843/B, D2: 690/B
BFS: angle: 4.00, D3: 730/B, D4: 671/B
8221 FFS: angle: 4.00, D1: 3450/B, D2: 2970/B
BFS: angle: 4.00, D3: 2991/B, D4: 2747/B
Best regards,
Krakow group
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