1. 1 Background Monitoring in the DIRC MDI meeting, May 25 th 2006 Nicolas Arnaud  Automatic monitoring  A few plots  What’s next?

2. 2 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/

3. 3 Plots: the ‘storm’ period between Tuesday and Wednesday Scaler comparison: raw rates (kHz) Scaler comparison: rate ratios 400 kHz 1 2

4. 4 Plots: things get better in the next 24 hours period 400 kHz 1 2 Scaler comparison: raw rates (kHz) Scaler comparison: rate ratios

5. 5 Plots: background increase quicker than ‘expected’

6. 6 Plots: background change between last week and this week A different tuning!?

7. 7 Plots: difference visible in the scope plot as well More background The ‘storm’

8. 8 Plots: Backgrounds were lower last October Smoother increase of scaler rate with growing luminosity All scaler rates below 300 kHz even with lumi above 9!

9. 9 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…