PRELIMINARY RESULTS

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PRELIMINARY RESULTS NOISE FROM RPC'S M.
GÓRSKI, WARSAW Histograms containing number of
hits for each strip per 10 seconds of the RPC's
may me accumulated example shows two chambers
Number of hits vs time
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Quiet chamber average noise 0.5 Hz/cm2
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Several peaks in time up to 600 Hz/cm2 on
certain strips
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SOMETIMES WE OBSERVE PEAKS IN THE TRIGGER RATE
PROVIDED BY RPC'S
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Such peaks in trigger rate are correlated in
time with chamber noise, mostly we observe a
peak in several chambers (20) suggesting
electric pickup
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The masking procedure is applied after trigger
system setup to ignore noisy strips (or maybe
electrronics channels only). A strip survives if
its noise lt 100 Hz/cm2 There is a hard-core
group of strips, which are detected as noisy
every time (lt1)? But a strip maybe quiet at one
moment and noisy afterwards... Following plot
shows maximal rate over 2h of data taking for a
group of chambers from the wheel W0 for all the
strips
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The noise histograms are a useful tool to
study the trigger behavior. The strange effects
seen on a single strip or even whole chamber do
not influence trigger rate.