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Re: Talk 2: v3



Hall D PID Mail List:

Hi David -

   I am not sure if it is even possible, but I think what Yves
wanted to show is what the "dE" plot would look like. E.g.
don't compute "dx". This is obviously going to look REALLY
BAD, but it points out the importance of knowing the path
length through the straws.

   cheers  -- Curtis
On Mon March 24 2008, David Lawrence wrote:
> 
> Hi Yves,
> 
>     I guess I'm still confused. Let me describe how those plots were 
> made and then maybe we can figure out what else is needed.
> 
>     The plots were made by letting GEANT track the particles through the 
> full detector w/ full magnetic field map and record the energy deposited 
> in the gas volume for each straw. The sum of energy deposited in the gas 
> by all straws was taken as dE. The tracks were then swum through by the 
> reconstruction code using the known starting parameters. The path 
> through each straw was estimated by a straight line at the calculated 
> point of closest approach that the track made with the wire. The total 
> path length through the gas of each straw used to make dE was added up 
> to make dx. Note that this did not use fit tracks and the fitter does 
> not include energy loss. Both of these would only work to make the 
> estimation of dx worse due to multiple scattering and energy loss.
> 
>     In the end, the culmination of all of these effects should make the 
> dE/dx values shown worse than what is actually expected. Does this clear 
> anything up?
> 
> Regards,
> -David
> 
> 
> Yves Van Haarlem wrote:
> > Hi David,
> >
> >>   I will get you the plots for 1 today, but I'm not sure what is 
> >> meant by
> > Thanks
> >
> >> "no correction for distance" in 2. Are you talking about the 150MeV/c 
> >> cutoff?
> > I believe people meant a dE/dx plot which is not corrected for path 
> > length in the straw.
> >
> > Cheers,
> >     Yves
> >
> >
> >
> >
> >
> >
> >>
> >> Regards,
> >> -David
> >>
> >> Yves Van Haarlem wrote:
> >>> Hall D PID Mail List:
> >>>
> >>> Hi All,
> >>>
> >>> While students are playing capture the flag and singing songs in the 
> >>> building I prepared version 3 of talk 2. It can be found on the 
> >>> usual wiki page and is waiting for your comments.
> >>>
> >>> Plots that I do not have but were requested during the dry run:
> >>>
> >>> 1 - Radiation length plot for a 90 and a 20 degree track (for slide 6)
> >>> 2 - dE/dx plot with no correction for distance, I was told this plot 
> >>> already exists (for slide 27)
> >>>
> >>> David could you provide a link to these plots?
> >>>
> >>> Thanks!
> >>>
> >>>
> >>> Cheers,
> >>>     Yves
> >>>
> >>>
> >>> ps. You can also use this link:
> >>>     http://www-meg.phys.cmu.edu/~yvhaarle/cdctalk.pdf
> >>>
> >>>
> >>>                           /--------------------------------
> >>>                          /   Yves Van Haarlem
> >>>        _--~~--_         /
> >>>      /~/_|  |_\~\      /      Carnegie Mellon University
> >>>     |____________|    /        Department of Physics
> >>>     |[][][][][][]|:= /          Wean Hall room 8404
> >>>   __| __         |__ \            Pittsburgh, PA 15213
> >>>  |  ||. |   ==   |  | \           USA
> >>> (|  ||__|   ==   |  |) \
> >>>  |  |[] []  ==   |  |   \           Tel.:   +1 412 268-6949
> >>>  |  |____________|  |    \                  +1 412 641-9252
> >>>  /__\            /__\     \          Fax.: +1 412 681-0648
> >>>   ~~              ~~       \-----------------------------------
> >>>
> >>> On Wed, 19 Mar 2008, Yves Van Haarlem wrote:
> >>>
> >>>> Hi All,
> >>>>
> >>>> The updated version of talk 2 is now available on the wiki page:
> >>>>
> >>>> http://www.jlab.org/Hall-D/software/wiki/index.php/DC_and_PID_Review
> >>>>
> >>>>
> >>>> Cheers,
> >>>>     Yves
> >>>>
> >>>>                          /--------------------------------
> >>>>                         /   Yves Van Haarlem
> >>>>       _--~~--_         /
> >>>>     /~/_|  |_\~\      /      Carnegie Mellon University
> >>>>    |____________|    /        Department of Physics
> >>>>    |[][][][][][]|:= /          Wean Hall room 8404
> >>>>  __| __         |__ \            Pittsburgh, PA 15213
> >>>> |  ||. |   ==   |  | \           USA
> >>>> (|  ||__|   ==   |  |) \
> >>>> |  |[] []  ==   |  |   \           Tel.:   +1 412 268-6949
> >>>> |  |____________|  |    \                  +1 412 641-9252
> >>>> /__\            /__\     \          Fax.: +1 412 681-0648
> >>>>  ~~              ~~       \-----------------------------------
> >>>>
> >>
> >> -- 
> >>
> >> ------------------------------------------------------------------------
> >> David Lawrence Ph.D.
> >> Staff Scientist                 Office: (757)269-5567   [[[  [   [ [ 
> >> Jefferson Lab                   Pager:  (757)584-5567   [  [ [ [ [ [ 
> >> http://www.jlab.org/~davidl     davidl@jlab.org         [[[  [[ [[ [[[
> >> ------------------------------------------------------------------------
> >>
> >>
> >>
> 



-- 
Professor Curtis A. Meyer        Department of Physics
Phone:  (412) 268-2745          Carnegie Mellon University
Fax:    (412) 681-0648            Pittsburgh PA 15213-3890
cmeyer@ernest.phys.cmu.edu  http://www.curtismeyer.com/