Re: references on the precision TOF

[Elke-Caroline Aschenauer <elke@jlab.org>]

On Tue, 31 Jul 2007, Andrei Semenov wrote:

Dear Andrei,

thanks for sending the information.

have a nice day elke


> Date: Tue, 31 Jul 2007 20:39:57 -0400 (EDT)
> From: Andrei Semenov <semenov@jlab.org>
> To: Elke-Caroline Aschenauer <elke@jlab.org>
> Cc: halld-cal@jlab.org, halld-pid@jlab.org
> Subject: references on the precision TOF
>
>
> 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
> >
>

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