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Background Monitoring in the DIRC

MDI meeting, May 25th 2006

Nicolas Arnaud

Automatic monitoring

A few plots

What’s next?

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DIRC background monitoring

Package DrcBackgroundMonitor Dedicated (software) IOC: drc-soft

Code developped between August and October 2005 Motivation: period of high background in the DIRC (June-July 2005)

Plots produced daily since the startup of Run 5b ‘Daily’ plots (last 3 shifts) updated around 08:20 every morning Cover previous day, swing and owl shifts ‘Biweekly’ plots (last 14 days) updated daily right after Midnight including plot for the weekly background report

All plots easily available via webpages automatically updated: Most recent plots: http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/BackgroundMonitoring/Html/dailyPlots.html Archives: http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/BackgroundMonitoring/Html/plotTables.html Background monitoring central webpage: http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/BackgroundMonitoring/

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Plots: the ‘storm’ period between Tuesday and Wednesday

Scaler comparison:raw rates (kHz)

Scaler comparison:rate ratios

400 kHz

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Plots: things get better in the next 24 hours period

400 kHz

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Scaler comparison:raw rates (kHz)

Scaler comparison:rate ratios

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Plots: background increase quicker than ‘expected’

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Plots: background change between last week and this week

A different tuning!?

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Plots: difference visible in the scope plot as well

More background

The ‘storm’

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Plots: Backgrounds were lower last October

Smoother increase of scalerrate with growing luminosity

All scaler rates below 300 kHzeven with lumi above 9!

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What’s next

Daily survey of the scaler rates Shifter instructions updated

Do operators know about DIRC signals? Were they told to use them to tune the beams?

Look for source(s) of new background (Jerry, back at SLAC end of the month)

Discuss background issues during next DIRC meetings Question: do we need additional shielding? [Certainly too early to answer now]

Present setup of scalers (12 DIRC scalers + 3 neutron counters): Integrate hits during 0.5 second every 4 seconds Impossible to get quantities insensitive to trickle injection with this config

Background characterization MD should come neither too early nor too late…