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.