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Re: PS target issues



Hrachya and all,

Perhaps a better basis for evaluating the relative importance of 
multiple scattering is to compare it with the beam spot size effect, 
rather than the counter width which is whatever we want it to be.  The 
rms spot size projected onto the horizontal axis is 1.0mm.  That number 
folded with the counter width / root(12) is the resolution prior to 
smearing due to multiple scattering.

Richard Jones



Hrachya.Hakobyan wrote:
>
>  Hello Jim,
>
> I've promised to give a numbers for multiple scattering influence. In 
> my recent mail, I've brought the following ones:
>
> -------------------------------------------------------------------------
> The  multiple scattering cone's spot size (horizontal projection 
> angle's RMS times 3.5m converter distance from FSF and WSF arms  ) is 
> ranged from:
> - 0.2 to 0.62mm for thicknesses x=10^-3 to 10^-2 Xo and Pe=8GeV/c - 
> 0.45 to 1.15mm for thicknesses x=10^-3 to 10^-2 Xo and Pe=3.5GeV/c
> -----------------------------------------------------------------------
>
> For comparison the coordinate resolutions for FSF and WSF arms in 24x6 
> PS's  configuration are:
>
> WSF arm - a) sigmaX= 0.72mm and 0.58mm for Pe=7 and 8GeV/c strips
>           b) sigmaX= 1mm in case when both strips have a width
>              app. 3.5mm equal to beam spot size        .
>
> FSF arm - <sigmaX> = 1.7mm
>
>
> Shift of  of the PS converter to 2.5m upstream increases the distance 
> to detectors from 3.5 to 6m, introducing a scale factor 1.714 and 
> modifying numbers as a following:
>
> - 0.34 to 1.06mm for thicknesses x=10^-3  10^-2 Xo and Pe=8GeV/c
> - 0.77 to 1.77mm for thicknesses x=10^-3 to10^-2 Xo and Pe=3.5GeV/c
>
> As you may see an impact of multiple scattering is quite important and 
> comparable with detectors coordinate resolution  and becomes even 
> dominant at 6m base and thicknesses  x>4x10^-3Xo.
>
> Hrachya
>
>
>