Re: systematic contributions to time-of-flight resolution

[Simon Taylor <staylor@jlab.org>]

Hall D PID Mail List:

Hi, Matt.

You are right, this is not a study of the intrinsic resolution of the 
time-of-flight counters, which is assumed to be perfect for the purpose 
of the study.    Rather this is a study of the contributions due to 
momentum resolution and path length variations to the uncertainty in 
calculated flight time for a particular particle type.   This impacts 
the interpretation of the time measured in the TOF or BCAL.

Simon

Matt wrote:
> Hi Simon,
>
>     Is this a study of resolution of TOF? Or a study of the resolution 
> on how we will reconstruct the path length? The time-of-flight will 
> just be the time-of-flight as calculated from the start time 
> (accelerator RF) and the stop time from some detector (BCAL/forward 
> TOF), independent of what path it took to get there. Resolution on the 
> TOF will be dependent on those quantities as well.
>
>     Isn't it more accurate to say this study is looking at the 
> resolution of our swimming routine and the path length that it 
> returns. I might be too picky...I wasn't sure if this was for the 
> review or just some internal study. Or perhaps I missed something.
>
> Matt B.
>
>
> On Tue, Mar 25, 2008 at 9:06 AM, Simon Taylor <staylor@jlab.org 
> <mailto:staylor@jlab.org>> wrote:
>
>     Hi, everyone.
>
>     I have started looking at the contribution to the time-of-flight
>     resolution due to the momentum resolution, path length variations, and
>     z-vertex position variations.  I have attached a plot of
>     resolution in the difference between the true flight time to
>     either the BCAL
>     or the TOF (as determined from the MC truth points) and the
>     reconstructed
>     flight time using the path length derived from swimming the
>     reconstructed
>     track from the vertex position to either the first TOF plane or
>     the inner
>     BCAL radius.  I threw 1.0, 2.0, and 3.0 GeV/c pions from the
>     center of the
>     target uniformly in phi and flat in theta from 126 degrees to ~0.5
>     degrees.  I find that the time resolution does not depend on the
>     momentum
>     in the barrel region but does for tracks that would hit the TOF.
>     Comments welcome.
>
>     Simon
>
>
>
>
> -- 
> -- 
> ----------------------------
> Matt Bellis
> Carnegie Mellon University
> (office) 412-268-6949
> (cell) 412-310-4586
> ----------------------------