Re: FDC Material and Noise Rates

[David Lawrence <davidl@jlab.org>]

Hi Matt,

    We also need to get the newer magnetic field map in since that has a 
slightly larger field, it could significantly cut down on the background 
rates near the beamline. It will also cut into our angular acceptance so 
we'll need to look into that as well. Richard and I are working on this 
and I will let you know when it is done.

-David

Matthew Shepherd wrote:
>
> I've posted a Wiki page outlining Richard's changes to FDC geometry 
> (Richard, check this!) and also some plots showing noise rate in the 
> FDC vs. plane number and also in the TOF.  There is a significant 
> difference -- for example the new geometry halves background rates in 
> the TOF.
>
> This also probably highlights the sensitivity of our background rate 
> calculations to material in the beam line.  We should think about 
> whether or not there systematic errors in these studies that might 
> cause us to significantly miscalculate the backgrounds.
>
> The plots can be found under the FDC page on the Wiki:
>
> http://www.jlab.org/Hall-D/software/wiki/index.php/Impact_of_FDC_Design_on_Noise_Rates 
>
>
> Mihajlo is working on evaluating the changes in FCAL photon 
> reconstruction efficiency.
>
> -Matt
>

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