Results from the Straws
Straw Residual Study
September 19, 1996
These plots compare the positions of tracks in the PWCs to hits in the
straws (the so called residual). Each layer of straws (of which there
are 27) has its own plot and all straws in that layer were used in
making the plot. These plots were made using photon data. The
background is from PWC tracks that did not have a corresponding hit in
thew straw layer, and in general mimics the pair region hit profile.
The straws were run at 1500 volts which is a fairly inefficent region
(see the
platau study) as a result the rate of incorrect association is
quite high. Each bin is one straw radius wide and no timing
information was used. Therefore we would expect the residual peak to be
two bins wide.
These residuals represent the next step in a logical progression to
full integration of the straws into e831. As I see it the major work
left to be done is as follows:
- Track residuals. Plots very similar to these but using the
tracking algorithm currently under development.
- High voltage platau study with traking.
- Threshold study with tracking.
After these two studies are complete the straws will be ready to take
real physics data. Further studies will be needed to improve
offline reconstruction:
- Time profile studies to determine t0 and drift velocity straw by
straw.
- Absolute tracking efficiency as measured against the PWCs.
Jon Link, link@ucdhep.ucdavis.edu