resolution with resistive Micromegas P Colas S Suvorov M Zito dE dx essential in detailed Higgs and top analysis PID for B and charm reconstruction b charge ID: 1046388
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1. Measurement of dE/dx resolution with resistive MicromegasP. Colas, S. Suvorov, M. Zito
2. dE/dx essential in detailed Higgs and top analysis (PID for B and charm reconstruction, b charge tagging)So far used successfully in the T2K ND280 TPCfor e/µ separationBut this was a standard anode TPC, with no charge sharing. We have to investigate the effect of charge sharing on dE/dx resolution, using DESY test beam data.Introduction29/05/2018dE/dx with resistive Micromegas2K. Abe et al., ‘Measurement of the intrinsic electron neutrino component in the T2K neutrino beam with the ND280 detector’, Phys.Rev. D89 (2014) 092003pads meshEB~100m Amplification gap: resistive foil: ~75minsulator: ~100m
3. Data 2014 middle module (mod 3) is extremely stableother modules show degradation in timestrategy: make pseudo-long track from 8 different tracks crossing the middle moduleData 2015long tracks along all three modules can be usednot all the pads can be used strategy: extract dead pads from the study29/05/2018dE/dx with resistive Micromegas3Used 2014 and 2015 campaigns to estimate dE/dx resolution. 5 GeV/c electron beam along the pad columns24 rows (the 1st and 24th receive 50% of the charge, the other 50% are lost in the crack between modules due to E-field distortion)Method:For each pad take maximum charge from ADC ()Sum up pads in a row to make a cluster ()For each track sort in increasing order (N clusters per track)Take first clusters.Truncated mean energy per clusterVary to reach best resolution
4. 29/05/2018dE/dx with resistive Micromegas4Calibration: equalize row-charge most probable valuesDo not use 1st and 24th line (they receive only part of the charge), but count them as inefficient, to be conservative.rowrowMost probable charge per roww/o calibrationw/ calibrationCharge per row
5. 29/05/2018dE/dx with resistive Micromegas5First check: 1 module 22 rows x 7 mm B = 0 w/o calibrationw/ calibrationE = 140 V/cmE = 230 V/cm
6. 29/05/2018dE/dx with resistive Micromegas6No significant dependence on drift distance observed (B=0 data)Drift, cmResolutionDrift, cmE = 140 V/cmE = 230 V/cm
7. 29/05/2018dE/dx with resistive Micromegas7rowDrift (cm)No dependence on drift distance observedB= 1T Data
8. 29/05/20188Charge per rowData samples taken in 2015Some pads were disconnected exclude them from PID studydE/dx with resistive Micromegas
9. 9Cross check of the dead pads with the variation of the beam positiondead pads29/05/2018dE/dx with resistive Micromegas
10. 29/05/2018dE/dx with resistive Micromegas10Apply multi-module selection (one long track across 3 modules)Vary to reach the best resolution : =0.7Use 20+19+21=60 rows, 42.5 cm , which corresponds to , for the full length (8 modules) RESULTS truncation parameter) dE/dx resolution
11. 29/05/2018dE/dx with resistive Micromegas11The dE/dx resolution for the ILD TPC track length (8 modules of 24 rows) is 5.0 % -> no significant degradation by the resistive foilStudy the dependence of the resolution on the drift distance, energy, peaking time, was performed: no dependence is observed 230 V/cm field is slightly better than 140 V/cmTo be studied: correlation between rows (due to transverse diffusion or charge spreading) might increase the dE/dx uncertainty and affect the L-0.5 track length dependence of the resolution. CONCLUSIONS