Re: [Brahms-dev-l] bug in bb calibration modules

From: Djamel Ouerdane <ouerdane@nbi.dk>
Date: Wed Apr 14 2004 - 07:06:31 EDT
Hi Hiro and others,

Let me clarify one thing about the BB time cal: modules were written 
originally according to what Yury et al had implemented. The delta TDC was 
done first since it allowed an easier alignment of the tubes before the 
slewing effect was evaluated. In the slewing formula, there's an extra 
delta TDC (the time limit at infinitely high ADC). 

When I wrote these modules, I thought about it and didn't like it but I
chose to be conservative and Flemming supported that. Then someone
introduced an option in the deltaTDC module so that slewing could be done
first. I never reacted to that because I simply didn't know about this
option (or forgot it, maybe I introduced this option myself, but then, I
don't remember it at all). When I think about it now, it doesn't make
sense since the slewing formula has already a delta TDC parameter so there
is no need to do a deltaTDC cal after slewing correction (in principle at
least).

What I don't understand is the way you can get a width of 1cm with the big
tubes when you do slewing before deltaTDC. In this case, the deltaTDC you
get after the slewing correction should be very close to zero. So why
doing this extra cal ? Also, when the deltaTDC vs large ADC correlation
looks so odd, how can you get such a width ? So, it tells me that there
either is a software bug or a real hardware problem. But the bug you're 
talking about sounds really odd to me.  

Djam


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Received on Wed Apr 14 07:14:09 2004

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