Re: BB vertex vs MRS tracks

From: Djamel Ouerdane (ouerdane@nbi.dk)
Date: Wed Oct 24 2001 - 15:04:21 EDT

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    On Wed, 24 Oct 2001, Stephen J. Sanders wrote:
    
    > Hi Djamel,
    > Nice figures.   A question, however:   If I download the latest brag and 
    > use it with the
    > run 5326 calibration, does your last figure indicate that I will have to 
    > apply an
    > additional offset of 18.07 cm to get the correct BB vertex?
    > 
    > ...steve
    > 
    
    Hi Steve, 
    
    yes, you're absolutely right. In fact, there will be soon a vertex 
    calibration package inserting offsets in the database for BB ZDC and so 
    on. I realized (and Flemming wonders about it) that this offset 
    fluctuates. It needs some calibration every week at least. It's on its 
    way...
    
    Note that you have to be aware that this offset only applies for the small 
    tubes. But the efficiency in the small tube vertex finding is very 
    good (around 0.97 in the sample I've scanned BEFORE requiring MRS tracks).
    
    Ciao
    Djam
    
    -- 
    Djamel Ouerdane ------------------------------------------o
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