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RPC Timing ResultsRPC Timing Results
with Final Splitterswith Final Splitters
Gianpaolo CarlinoGianpaolo Carlino
INFN NapoliINFN Napoli
The Napoli RPC Group:
M.Alviggi, V. Canale, M. Caprio, G.C., R. de Asmundis, M.Alviggi, V. Canale, M. Caprio, G.C., R. de Asmundis, M. Della Pietra, D. Della Volpe, P.Iengo, S.Patricelli, M. Della Pietra, D. Della Volpe, P.Iengo, S.Patricelli,
L. Romano, G. Sekhniaidze L. Romano, G. Sekhniaidze
Outline
• Napoli Test Station Napoli Test Station • Efficiency and Multiplicity MeasurementsEfficiency and Multiplicity Measurements• RPC Time Distributions with ‘Final Splitters’RPC Time Distributions with ‘Final Splitters’• Comparison between Standard and Wired OR Comparison between Standard and Wired OR
Strip Readout as a function of thresholdStrip Readout as a function of threshold• ConclusionsConclusions
The ‘Final Splitter’ in the one designed in Roma 1.It will be used on the experiment but not in the RPC tests
TriggerTrigger• TOP & BOTTOM layerTOP & BOTTOM layer• 2 x 1 m2 x 1 m22 sscintillatorscintillators
Tracking systemTracking system• 2 Drift chambers2 Drift chambers• 2 x and 2 y plane per layer2 x and 2 y plane per layer• Resolution in track Resolution in track
reconstruction reconstruction ~ ~11 m mmm
The 2 modules housing The 2 modules housing
scintillators & tracking chambers scintillators & tracking chambers
are moved by step motors are moved by step motors
automatically during data takingautomatically during data taking
4.5 m
1.8 m
3.5 mThe Test Station
Each chambers has 2 X layers and 2 Y layersEach chambers has 2 X layers and 2 Y layers
To disentangle the To disentangle the left-right ambiguity, left-right ambiguity, each layer is each layer is staggered respect to staggered respect to the other one on the the other one on the same viewsame view
Golden Event:Golden Event:Fully Reconstructed Tracks with 1 hit per layer
(50% Selection Efficiency)
The Drift Chambers
FinalSplitter TDC
32 stripsRPC type:RPC type:
BOS - B 004
Working Point:HV = 10.500 VHV = 10.500 V
Threshold = 0.59 mVThreshold = 0.59 mV
Experimental Setup
Expected strip
Some Definitions:
Physical Strip:Physical Strip:
Fired Strip corresponding to the Expected Strip
Physical Cluster:Physical Cluster:
Cluster with the Physical Strip
Expected Strip:Expected Strip:
Strip given by the Impact Point of the Track on the RPC surface
Efficiency:Efficiency:
Event with a Physical Strip
StripStripAv. Multi = Av. Multi =
1.581.58
Cluster Cluster Av. Multi = 1.08Av. Multi = 1.08
RPC Multiplicity for Strips and
Clusters
Cluster Sizes
Physical ClustersPhysical ClustersAv. Size = 1.57Av. Size = 1.57
Other ClustersOther ClustersAv. Size = 1.11Av. Size = 1.11
Efficiency = Efficiency = 0.9600.960
In the definition of the efficiency we use a tolerance
of 5 mm InefficiencyInefficiency
RPC Efficiency as a function of Strips
We expect to improve the We expect to improve the efficiency with a more efficiency with a more
precise RPC alignment precise RPC alignment (under study)(under study)
Spacers
Tracks Impact Points of the RPC Surface for Inefficient Events:
SpacersSpacers
Peak 1Peak 1
Peak 2Peak 2
Peak 3Peak 3
RPC Times Distribution
Multi-hit TDC
More than one Pulse could be
recorded for each Strip
The Trigger Logic could be in trouble
because of the presence of more than one pulse
from the same strip.Trigger People are able to solve this problem
- RPC Time -Percentage of
Peaks presence as a function of the
threshold
Physical Strip Physical Strip ONLY !!ONLY !!
Only Peak 1Only Peak 1
Peaks 1+2Peaks 1+2
All PeaksAll Peaks
- RPC Time - Percentage of
Peaks presence as a function of the
threshold
All other Strips in All other Strips in the Physical Clusterthe Physical Cluster
Only Peak 1Only Peak 1
Peaks 1+2Peaks 1+2
All PeaksAll Peaks
RPC Times Pulse Widths
Physical ClustersPhysical Clusters
Other ClustersOther Clusters
- Peak 1 -
Longer Widths could Longer Widths could be obtained with a be obtained with a modification of the modification of the
Front End ElectronicFront End Electronic
Example of Pulse Widths for 2 Strips
Pulse Width DistributionsAverage pulse width is about 8 ns.Some channels show shorter pulses.Let’s divide strips in two categories:
Long and Short Pulse Strips
ShortShort
LongLong
ShortShortLongLong ShortShort
- RPC Times –Time Difference
between Physical and Other Strips
Physical Physical ClustersClusters
Other ClustersOther ClustersThe Large Time Difference The Large Time Difference between strips in the same between strips in the same cluster must be taken into cluster must be taken into
account for the declustering account for the declustering algorithm and the bunchlet algorithm and the bunchlet
identificationidentification
- Peak 1 -
RPC Times - Peak 1
Time Difference between Time Difference between Physical and neighbor Physical and neighbor
Strips as a function Strips as a function of the Cluster Sizeof the Cluster Size
Size = 2Size = 2
Size = 3Size = 3 Size = 4Size = 4
Only Physical Cluster Strips
Time Difference between Time Difference between Physical and neighbor Physical and neighbor Strips as a function of Strips as a function of
Strip Distance (Strip Distance ())
RPC Times - Peak 1
Only Physical Cluster Strips
= 1 = 1
= 2 = 2 = 3 = 3
-
Str
ips
FinalSplitter
TDC
Comparison between Standard and Wired OR Strip Readouts as a function of Threshold
FinalSplitter
TDC
Wired OR ReadoutWired OR Readout
Standard ReadoutStandard Readout
Will be used for Will be used for strips strips
Multiplicities Comparisonas a function of the threshold
Cluster Sizes Comparison
Wired - ORWired - OR
Efficiency Comparison with Wired - OR as a function of the threshold
The efficiency loss in the The efficiency loss in the Wired OR Readout could Wired OR Readout could be reduced with a precise be reduced with a precise
tuning of the thresholdtuning of the threshold
Conclusions
• The results of a test performed on 32 The results of a test performed on 32 strips of a BOS strips of a BOS RPC have been shown.RPC have been shown.
• The RPC Efficiency and Multiplicities are in agreement The RPC Efficiency and Multiplicities are in agreement with expectations.with expectations.
• Timing Results:Timing Results:– The presence of more than one pulse per strip has to be taken into The presence of more than one pulse per strip has to be taken into
account in the trigger logic.account in the trigger logic.– Some modifications of the Front End Electronics are needed in Some modifications of the Front End Electronics are needed in
order to get longer strip pulses.order to get longer strip pulses.– The difference in the time response of strips belonging to the same The difference in the time response of strips belonging to the same
cluster needs a more detailed study and an adequate simulation in cluster needs a more detailed study and an adequate simulation in the Trigger Simulation Program.the Trigger Simulation Program.
• The analysis will be repeated (and this results confirmed) The analysis will be repeated (and this results confirmed) with larger statistics as soon as we will have in Napoli more with larger statistics as soon as we will have in Napoli more chambers and splitters to test.chambers and splitters to test.