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Fiber tests Results from Jlab



Hi All,
I added some information in two links about the fiber test on the wiki and can be
found at:
http://www.jlab.org/Hall-D/software/wiki/index.php/BCAL#Scintillation_Fibers
The two links are:
1) http://www.jlab.org/Hall-D/software/wiki/index.php/Fiber_Test_Results_K
    which summarized the results and addresses two issues raised by Andrei about a
    possible correlation between attenuation length and mean number of photo electrons 
   (there is non), and the way the second fiber end is treated.
   The conclusion is that the fibers fulfill the specifications stated in the contract:
   mean number of photo electrons > 3.5
   bulk attenuation length >= 300cm
   variation in these numbers <= 10%

2) http://www.jlab.org/Hall-D/software/wiki/index.php/CAEN_V792N_ADC
    describes the behavior of the ADC I used and why I needed a linear fan in/out
    to have the possibility to add a negative DC offset to the signal. Only in this way
    I can clearly raise the single photo electron peak out of the threshold with good 
    resolution.
    However, the behavior of the ADC is intrinsic to any charge integrating ADC
    and explains why I think that covering a dynamic range of 1000 is very difficult 
    using only one amplification/integration path for a given readout-channel.

cheers,
Beni

-- 
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Benedikt Zihlmann
TJNAF
HallD 12C/ F350
Suite 8
12000 Jefferson Av.
Newport News VA, 23606

tel: 757 269 5310 
fax: 757 269 6331                zihlmann@jlab.org
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