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Timing Study of VSVX Occupancy. Yurii Maravin FNAL. Data samples. 10 special runs taken 01-10-03 VSVX threshold set to max (~7 p.e.) Integration window shifted around the default value in the range of –93.3 ns to +113.0 ns More details: CFT_Log #168556. Data Samples. Analyze the data.
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Timing Study of VSVX Occupancy Yurii Maravin FNAL
Data samples • 10 special runs taken 01-10-03 • VSVX threshold set to max (~7 p.e.) • Integration window shifted around the default value in the range of –93.3 ns to +113.0 ns • More details: CFT_Log #168556
Analyze the data • Develop a code that creates root-tuple with VSVX hits information regardless on SVX data • Remove offline threshold (20 counts) • Implement root macros to analyze VSVX information: • Analyze VSVX occupancy (per layer, per trigger sector etc) • Search for missing SVX info (VSVX fired, SVX missing)
VSVX Occupancy Default Layer A C B maximal vsvx threshold (7 p.e.) D E F H G
VSVX Occupancy (cont) • Current position of the integration window is not optimal – VSVX occupancy is still going up if delayed • Can increase efficiency by another 40-60% by delaying ~50 ns: • VSVX efficiency per SVX hit: • Default: (53.7 +/- 3.4) % • +56.5 ns : (81.0 +/- 4.3) % • Interesting to see VSVX efficiency per SVX hits for 1% threshold.
Occupancy per trigger sector • In the next 9 slides, VSVX occupancy histograms are plotted as a function of a trigger sector • Please note that the distributions are not flat for the default settings. It is probably caused by the timing inefficiency
VSVX Occupancy for layer H -96 ns -60 ns -24 ns Default +18 ns +36 ns +54 ns +72 ns +108 ns
VSVX Occupancy SS# 1 SS# 2 SS# 3 SS# 4 SS# 5 Default maximal vsvx threshold (7 p.e.)
“Quality” of VSVX hits • We get much more VSVX hits if we delay the integration window • What about ADC information?
ADC distributions • Plot ADC values for fibers where VSVX fired: • Indication of • fibers with low ADC counts • invalid SVX value (SVX = 255) • missing SVX information (SVX=0)
VSVX = 1 and SVX = 0 (no counts) Related to hot VSVX channels? Compare geographical distributions of hits for all data and these with ADC != 0
–93.3 ns data All hits ADC != 0 Total hits with ADC = 0: 154,507. 63,137 of which (41%) of which are under ‘hot’ VSVX regions. Hot channels are not hot all the time!
How many hits do not have SVX info? Occupancy Hits with no ADC
Summary • VSVX occupancy results suggest delaying the edge of the integration window • Non flat VSVX hits distribution indicates timing inefficiency • VSVX hits distributions looks flat for Dt > 36 ns • However, a lot of VSVX hits with no ADC information!
Summary • Indication of hot VSVX channels, indication of missing SVX information • Can provide position of hot VSVX channels