Tracking results from Au+Au test Beam Jochen Markert For the Tracking group

Status DST gen0: Almost full calibration of all detectors alignment of all detectors (Shower done by hand) NOW: second iteration of calibration and alignment (new procedures by Vladimir) Overall improved tracking performance Kalman Filter almost ready MDC dE/dx to be done Investigations of tracking parameters ongoing

Improvements S3: tracks +8% chi2 -10% wires +2.3% S5: tracks +17% V. & O. Pechenov

Vertex Day 224 Field Vertex fit for field runs uses 2 inner MDCs simultaneously Sigma ~ 1.3 mm V. & O. Pechenov

Vertex Day 227 No Field Vertex fit for no field runs uses 4 MDCs simultaneously Better resolution compared to field on runs Sigma ~ 1.1 mm V. & O. Pechenov

Cluster Search And Fitting

Number of Layers in Segments Solid line for cluster Dashed line for fit Cluster search requires 10 layers at minimum Almost the same number of layers in cluster for MIPS and NonMIPS Less wires accepted in fit for outer segment (average loss 2 layers) compared to inner segment (average loss 1 layer)

Number of Wires in Segment Solid line for cluster Dashed line for fit Cluster search required 10 layers at minimum Less wires accepted in fit for outer segment (average loss 2 layers) compared to inner segment (average loss 1 layer)

Number of Layers in Segment Required layers in segment: >= 10 layers >= 11 layers =12 layers

Number of Wires in Segment Required wires in segment: >= 10 wires >= 11 wires >= 12 wires >= 13 wires >= 14 wires >= 15 wires >= 16 wires >= 17 wires

Track Fit

Drift Velocity vs. Electric Field Drift velocity of Ar/CO2 higher compared to Ar/i-butane No real plateau for Ar/CO2 Drift velocity very low at low electric field values for Ar/CO2

Drift Velocity Contours for MDCI Ar/i-butane Ar/CO2 Strong inhomogeneous drift velocity contour for Ar/CO2

Fit Deviation vs Distance from Wire Deviation = tmeasured – tcalculated Systematic deviation visible Origin: cal1/cal2 ? Needs to be investigated separately for each wire

Fit Deviation vs Distance from Wire Systematic effect stronger for NonMIPS compared to MIPS

Drift Time Resolution Resolution shows strong detoriation close to the sense wire Different shape for MDCI compared to other MDCs Better resolution for NonMIPS

Front end Setting Comparison

Evaluating 3 Scenarios Aug 15  Aug 16 - 19  Aug 17 spike rejection of TDCs in plane II = 23 ns Aug 16 - 19  from august 16, 13:42:00 on the spike rejection of TDC in plane II changed to 13 ns Aug 17 13:21:41 – 13:24:12 two runs with high threshold settings (0x60) and spike rejection of TDCs = 13 ns

Plane I, Sector 3, Layer 1 Rich structures in the measured drift data Question: Contain to additional structures “good” measurements with wrong time measurement ? T.Galatyuk

Plane II, Sector 3, Layer 1; 15 && 17-19 August Black curves = Day 227 Color = Day 229 – 231  spike rejection of TDCs has been changed from 23 ns to 13 ns T.Galatyuk 20

Plane I, Sector 3, Layer 1 Thr.>0x30 Thr.>0x60 Higher threshold reduce additional structures T.Galatyuk

Plane I, Sector 3, Layer 1 Factor of 10 suppression of the small ToT satellite T.Galatyuk

The combination of low thresholds (0x30) and 23 ns spike suppression of TDCs seems to be a better choice? T.Galatyuk

Momentum Distributions RPC ToF High spike rejection + low threshold or low spike rejection + low threshold seems to be featured T.Galatyuk

Mass Distributions RPC ToF p p d 3He t T.Galatyuk

Number of Wires in Cluster for different Front end Settings MIPS selected Low threshold + high spike rejection results in more wires in the cluster compared to standard setting

Number of Wires in Cluster for different Front end Settings NonMIPS selected Low threshold + high spike rejection results in more wires in the cluster compared to standard setting Less improvement compared to MIPS

Number of Wire in Segment for different Front end Settings MIPS selected Low threshold + high spike rejection results in more wires in the cluster compared to standard setting

Number of Wire in Segment for different Front end Settings MIPS selected Low threshold + high spike rejection results in more wires in the cluster compared to standard setting Less improvement compared to MIPS

Efficiency Studies Fully reconstructed tracks: inner + outer segment fitted Runge-Kutta fit succeeded Matched with Meta hit NonMIPS : beta < 0.6 MIPS : beta > 0.8

ToT as Function of Impact Angle into the Drift Cell NonMIPS Integration over distance from wire 5 degree angle bins Second bump at large ToT for MDCI due to strong drift velocity variation for ArCO2 angle particle  y x angle

ToT as Function of Impact Angle into the Drift Cell MIPS Second bump at large ToT almost vanished

Cell Efficiency from Segment Fit Impact angle and distance from wire known from segment fit Only accepted wires are taken into account Reference are wires which should have given a signal Efficiency limited due to segment fit ? Low values MDCIV ? Structures in MDCI ? particle  70% 70% 75% 58%

Cell Efficiency from Segment Fit Better efficiency compared to MIPS Still the same questions as before 73% 82% 80% 58%

Cell Efficiency from Segment Fit Difference between efficiency of MIPS and NonMIPS

Cell Efficiency from Cluster Impact angle and distance from wire known from segment fit wires from cluster are taken into account Reference are wires which should have given a signal Efficiency not limited due to segment fit, but noise or double hits are counted as “good” 80% 84% 90% 84%

Cell Efficiency from Cluster MDCIV now at high efficiency Conclusion: segment fit looses wires due to noise or wrong measurements (hardware, geometry,cal1, cal2) 80% 90% 92% 90%

Cell Efficiency from Cluster Difference between efficiency of MIPS and NonMIPS

Cell Efficiency results

Layer Efficiency Layer efficiency calculated from clusters Only clusters are selected which contain no multiple used wires Event multiplicity 10-30 selected, max multiplicity per sector < 8 tracks Long spike rejection + low threshold seems to be the most efficient combination T.Galatyuk

Probabilities T.Galatyuk

Comparison between Au+Au and Ar+KCl Layer efficiencies comparable 40 degree layers show lower efficiencies T.Galatyuk

Some layers show same efficiency structures The complete chamber has been build new. Front end electronics could be the reason T.Galatyuk

Thank you!

Time (from 0 to 100 ns) vs. Distance to wire (from 0 to 2.5 mm) Ar/i-butane Ar/CO2 Time (from 0 to 100 ns) vs. Distance to wire (from 0 to 2.5 mm)

Number of layers in module

Number of wires in module

13 ns, 0X38 23 ns, 0X38 23 ns, 0X60

Velocity vs. Momentum x charge RPC TOF

Time-of-flight spectrun in RPC b > 0 b < 0

Few cells misbehave

Mass distributions p RPC Shift of the peak position Mass „broadening“ scenario ;) Visible in ToF and RPC Also for other particles p T.Galatyuk

Performance of Start- detector Jerzy Pietraszko Wolfgang Koenig Performance of Start- detector Alpha spectra from Am source measured for the outer and central segments of the start detector Deterioration by 50 % within 5 days Aug 15 Aug 18