Strange looking Au data

From: Mads Mikelsen (mads.mikelsen@fys.uio.no)
Date: Wed May 21 2003 - 11:00:21 EDT

  • Next message: Claus O. E. Jorgensen: "Re: Strange looking Au data" 
    Hello!

I have taken a look at the Au data for the MRS. I have found problems
relating to one spectrometer setting in particular; 90degrees 1000B. (Runs
in aerea 5850 to 5990.)  By
plotting the average number of tracks versus run-number I get a stair-case
like distribution. (Three flat plataus with sharp increases separating
them. Each increase is around 20-25%.) -- See attached plot.

This indicates that something has happened with the detectors between
certain runs. (Tuning, triggers etc.)

Only trig 6 events with <5% centrality and vertex between -5 and 5cm have
been counted. (And with ok zdc vtx.)  And only primary tracks are counted.
(The number of identifiede pions etc. shows the same variation as primary
traks pr event.)

Has anyone noticed this before? Or is there any explanation?
Shurly someone must have done theese tests before.

I have not used the data from the latest reductions, since they are not
compatible with BDST. But Claus assured me that the QM data lockaded at
/brahms/data05/data/dst/MRS should be OK. (-- I do not expect that the
latest calibrations will give such a drastic effect.)

I have cheked the shiftreports from the shifts around the runs where the
sharp increases are located but has not not found anything that can
explain this.

I hope to get some comments soon as I plan to use the data for my thesis!
:-)

Best regards
     from Mads
    Plot

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