RPC Timing Results with Final Splitters Gianpaolo Carlino INFN Napoli The Napoli RPC Group: M.Alviggi, V. Canale, M. Caprio, G.C., R. de Asmundis, M. Della Pietra, D. Della Volpe, P.Iengo, S.Patricelli, L. Romano, G. Sekhniaidze

Outline Napoli Test StationNapoli 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 Strip Readout as a function of thresholdComparison between Standard and Wired OR Strip 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

Trigger TOP & BOTTOM layer TOP & BOTTOM layer 2 x 1 m 2 scintillators 2 x 1 m 2 scintillators Tracking system 2 Drift chambers 2 Drift chambers 2 x and 2 y plane per layer 2 x and 2 y plane per layer Resolution in track reconstruction  ~1 mm Resolution in track reconstruction  ~1 mm The 2 modules housing scintillators & tracking chambers are moved by step motors automatically during data taking 4.5 m 1.8 m 3.5 m The Test Station

Each chambers has 2 X layers and 2 Y layers To disentangle the left- right ambiguity, each layer is staggered respect to the other one on the same view Golden Event: Fully Reconstructed Tracks with 1 hit per layer (50% Selection Efficiency) The Drift Chambers

Final Splitter TDC 32  strips RPC type: BOS - B 004 Working Point: HV = V Threshold = 0.59 mV Experimental Setup

Expected strip Some Definitions: Physical Strip: Fired Strip corresponding to the Expected Strip Physical Cluster: Cluster with the Physical Strip Expected Strip: Strip given by the Impact Point of the Track on the RPC surface Efficiency: Event with a Physical Strip

Strip Av. Multi = 1.58 Cluster Av. Multi = 1.08 RPC Multiplicity for Strips and Clusters

Cluster Sizes Physical Clusters Av. Size = 1.57 Other Clusters Av. Size = 1.11

Efficiency = In the definition of the efficiency we use a tolerance of  5 mm Inefficiency RPC Efficiency as a function of Strips We expect to improve the efficiency with a more precise RPC alignment (under study) Spacers

Tracks Impact Points of the RPC Surface for Inefficient Events:Spacers

Peak 1 Peak 2 Peak 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 ONLY !! Only Peak 1 Peaks 1+2 All Peaks

- RPC Time - Percentage of Peaks presence as a function of the threshold All other Strips in the Physical Cluster Only Peak 1 Peaks 1+2 All Peaks

RPC Times Pulse Widths Physical Clusters Other Clusters - Peak 1 - Longer Widths could be obtained with a modification of the Front End Electronic

Example of Pulse Widths for 2 Strips Pulse Width Distributions Average pulse width is about 8 ns. Some channels show shorter pulses. Let’s divide strips in two categories: Long and Short Pulse Strips Short Long ShortLongShort

- RPC Times – Time Difference between Physical and Other Strips Physical Clusters Other Clusters The Large Time Difference between strips in the same cluster must be taken into account for the declustering algorithm and the bunchlet identification - Peak 1 -

RPC Times - Peak 1 Time Difference between Physical and neighbor Strips as a function of the Cluster Size Size = 2 Size = 3 Size = 4 Only Physical Cluster Strips

Time Difference between Physical and neighbor Strips as a function of Strip Distance (  ) RPC Times - Peak 1 Only Physical Cluster Strips  = 1  = 1  = 2  = 3

 - Strips Final Splitter TDC Comparison between Standard and Wired OR Strip Readouts as a function of Threshold Final Splitter TDC Wired OR Readout Standard Readout Will be used for  strips

Multiplicities Comparison as a function of the threshold Cluster Sizes Comparison

Wired - OR Efficiency Comparison with Wired - OR as a function of the threshold The efficiency loss in the Wired OR Readout could be reduced with a precise tuning of the threshold

Conclusions The results of a test performed on 32  strips of a BOS RPC have been shown.The results of a test performed on 32  strips of a BOS RPC have been shown. The RPC Efficiency and Multiplicities are in agreement with expectations.The RPC Efficiency and Multiplicities are in agreement with expectations. Timing Results:Timing Results: –The presence of more than one pulse per strip has to be taken into account in the trigger logic. –Some modifications of the Front End Electronics are needed in order to get longer strip pulses. –The difference in the time response of strips belonging to the same cluster needs a more detailed study and an adequate simulation in the Trigger Simulation Program. The analysis will be repeated (and this results confirmed) with larger statistics as soon as we will have in Napoli more chambers and splitters to test.The analysis will be repeated (and this results confirmed) with larger statistics as soon as we will have in Napoli more chambers and splitters to test.