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Re: references on the precision TOF



Hall D PID Mail List:


HI Alex et al.,

I would also like to remind everyone that the detector has a list of
design parameters which have been shown at numerous reviews (See for
example slide 12 of the overview at the DC review
http://argus.phys.uregina.ca/gluex/DocDB/0007/000749/009/Overview_v4.ppt)

We give 60 ps as the tof resolution, which has been presented many times
before. For the CD-2 review we give not only cost and schedule but also
a baseline for technical performance.  Changes to these parameters need to
be considered as changes to the baseline just as other aspects of the
project.

Cheers, Elton.



Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite # 16
Newport News, VA 23606
elton@jlab.org
(757) 269-7625

On Tue, 31 Jul 2007, Alex Dzierba wrote:

> Hi Andrei
>
> Thanks for this information - very valuable indeed.
>
> Alex
>
> At 8:39 PM -0400 7/31/07, Andrei Semenov wrote:
> >Elke:
> >
> >You can find the PDF file with the paper you asked for on the meeting
> >(viz., CERN NA49 detector description) on the web address
> >http://www.jlab.org/~semenov/na49-detector.pdf (it's too big for the
> >attachment); and the reference is NIM A430 (1999) 210.
> >TOFR wall (of about 2 m^2 area and 900 PMTs) was made
> >by Marburg U. group, and used Philips XP-2972 tubes; the overall TOF
> >resolution (viz., including start counter contribution as well as
> >electronics resolution and the 900-channels calibration misallignment) was
> >about 60 ps (sigma). TOFL wall (same area, same # of PMTs) was made by
> >Dubna group (myself included); it used Russian FEU-87 PMTs, and the
> >overall time resolution was about 75 ps (sigma). Surely, these detectors
> >are the "pixel" ones, but my point is that absolutely no special
> >"stabilization" of PMTs was necessary to reach such a resolution. Critical
> >decision (to reach such a resolution) was to remove the light guides and
> >couple PMTs directly to the scintillators. Another important moment was to
> >use the hit position from the TPC. And (of course) the quality of the
> >cables from PMTs to CFDs...
> >
> >You might be interested to have a look on the TOF paper from BESII/BESIII
> >experiment: http://www.jlab.org/~semenov/besII-tof.pdf or
> >NIM A555 (2005) 142. The guys used 230x5x6 cm^3 bars, and got about
> >90 ps resolution per bar. Again, it was more thick bar, and they used
> >fine-mesh Hamamatsu R5924 PMTs, but light dispersion should be about the
> >same => it's not an absolute limit that does not allow to reach a good
> >time resolution, and the optimization is possible.
> >
> >Thanks,
> >Andrei
> >
> >
> >
> >On Mon, 30 Jul 2007, beni zihlmann wrote:
> >
> >>
> >>  I probably did not express myself properly. The 150ps I quoted as TOF
> >>  resolution
> >>  is for one plane.
> >>  So one can assume that for two planes (horizontal+vertical) the timing
> >>  resolution
> >>  from the full device could reach 150ps/sqrt(2)=106ps. So there is
> >>  justified hope
> >>  that for the full device we can reach 100ps or even below. The only
> >>  caveat is that
> >>  while the efficiency will be high it will be not 100%, in particular
> >>  because we
> >>  do not stager the paddles but they are on top of each other or side by side.
> >>
> >>  cheers,
> >>  Beni
> >>
>
>
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Alex R. Dzierba
> Chancellor's Professor of Physics (Emeritus)
> Department of Physics / Indiana U / Bloomington IN 47405 / 812-855-9421
> JLab Visiting Fellow
> Jefferson Lab / 12000 Jefferson Ave / Newport News, VA 23606 / 757-269-7577
> Home Phone: 812-825-4063  Cell:  812-327-1881  Fax: 866-541-1263
> http://dustbunny.physics.indiana.edu/~dzierba/
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>