The need for this document underscores the importance of a long-term solution which would require no knowledge in the consumer.
Please send me corrections/suggestions/clarifications...
August 01, 2002
This page contains the following useful items:
Axial tracks are kept if they have either
|Problem||Most of my tracks have only 8 hits|
|Cause:||The geometry or calibration files are incorrect or missing. Make sure you've carefully followed the cookbook for data or MC|
|Problem:||My track phi distribution has big holes!|
|Cause:||You may be using a MC setup on real data. Specifically, make sure that the REALDATA parameter is set to TRUE for data. Otherwise, it may represent detector problems.Check your CFT configuration for data, or try a different run.|
|Problem:||I see lots of axial only tracks: spikes in Z or tan(lambda)|
|Cause:||If you've ensure that the system is configured correctly (check the distribution of the number of hits on the track, and see above if it peaks at 8 hits. Otherwise, this may be the desired performance -- many axial tracks are found below the threshold and no stereo tracking is performed. Check the correlation between the pt and the stereo information|
|Problem:||My tracks don't match my electrons/muons/etc|
|Cause:||If you're using the MC geometry on a data file or vice versa, then you'll see this problem. To confirm it, you will see very few SMT hits because the CFT is rotated with respect to the SMT and the rest of the geometry.|
|Problem:||My efficiency is very low!|
|Cause:||If you've ensured that the system is configured correctly (check the distribution of the number of hits on the track, and see above if it peaks at 8 hits), then make sure that you're calculating your efficiency in the CFT fiducial region. Remember that unlike offline tracking, online tracking is only performed in the central region, to an eta of roughly 1.1.|
|Problem:||My DCA resolution is very large|
|Cause:||The beam spot is shifted with respect to the center of the detector, so that the tracks will typically not come from (0,0). Unlike the offline tracking, the track parameters are always calculated with respect to the detector (0,0), so a plot of track DCA versus track angle will show a sine wave (see the reference plots). If you fit this sine wave and calculate the DCA relative to the beam spot, you should be able to get a DCA resolution of ~65 microns for tracks above 1 GeV.|
|Problem:||My Pt resolution is poor|
|Cause:||The Pt resolution is greatly enhanced by the addition of SMT information. Make sure that you have correctly configured the SMT so that the most likely number of hits on a track is 10 or 11 rather than 8 (see above).|
GEO L3GeometryManagement(MCTag="p10.06.01")| CFTUnp L3TCFTUnpack(realdata=FALSE)| SmtUnp L3TSmtUnpack|
GEO L3GeometryManagement( tooltype="utility", RunNo=-1, MCTag="xxx.xx.xx")| CFTUnp L3TCFTUnpack( tooltype="unpack", adcthreshold=20, maxfibers=8, realdata=TRUE)| SmtUnp L3TSmtUnpack( chanthreshold=.03, maxstrips=16, adcthreshold=10, clusterthreshold=.03, tooltype="unpack")|Note that "RunNo=-1" will give you the latest geometry available. If you instead insert a specific run number (like 123456), then it will use the geometry from the DB which was available for that run.
The CFT and SMT information must be merged by hand into one file. This file can be obtained from cvs: gtr_l3/bin/l3calib.merged.cftstereo2.ev and must be copied into your "trigsim" directory if you are using runD0TrigSim, or into your local directory if you are using another executable:
$ cp /d0dist/dist/packages/gtr_l3/devel/bin/l3calib.merged.cftstereo2.ev ./l3calib.ev