Analysis of the First Cosmic Ray Data Collected with the Complete ALICE TPC Philippe GROS

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20162 Structure QGP, ALICE and the TPC Irregularities in the Cluster Data Characteristics of Clusters in Tracks

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20163 Hadronic Matter baryons : 3 different colours ex : proton, neutron mesons : colour + anti-colour ex : pions - 6 quarks : up, down, charm, strange, top and bottom (+ anti) - 3 colours : red, green and blue (+anti) Normal matter is color neutral : quarks are in groups of 2 or 3 quark gluon

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20164 Quark Gluon Plasma Increase temperature (ALICE) Increase density (SPS) QG P Hadroni c Matter π p n p n Quarks

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20165 QGP : Phase Diagram QGP Early Univers e RHIC LHC SPS AGS Neutron Star ρ C ~1fm -3 T C ~200MeV Hadron Gas ρ T usus

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20166

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20167 Heavy Ion Collisions The LHC ATLAS ALIC E LHCb CMS 27 km circumference - ATLAS, CMS, LHCb : rare events in p+p 14 TeV (Tevatron : 2 TeV) - ALICE : all collisions in Pb+Pb 5.5 TeV per nucleon pair (RHIC : 0.2 TeV per nucleon pair) near Genève, on French-Swiss border Lac Léman Franc e Switzerlan d

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20168 The Alice Experiment MUON ARM L3 magnet CENTRAL BARREL

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/20169 The Alice Experiment TPC tracking, dE / dx

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ ALICE TPC 5 m 88 m 3 Ne-CO 2 (90-10) BergenBratislava CERNCopenhagen Darmstadt TUFrankfurt GSI DarmstadtHeidelberg KIP Heidelberg PIKrakow Lund The ALICE TPC Collaboration

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Operating Principle Diffusio n e e Constant drift velocity 2.84 cm μs -1 => time ~ distance => 3D Readout time : ~100 μs

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ ReadOut Sectors OROC IROC 4x7.5 mm 2 6x10 mm 2 6x15 mm 2 Total > pads (electronic channels) 2 x 18 sectors 8x8 pads pad wire

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : PASA Pad signal has a long tail due to slow drifting ions

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : PASA Pad signal is amplified and shaped

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : ALTRO ~digital oscilloscope Total data in one event : ~ 1 GByte

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : ALTRO ~digital oscilloscope Total data in one event : ~ 1 GByte

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : ALTRO ~digital oscilloscope Total data in one event : ~ 1 GByte

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : ALTRO ~digital oscilloscope Total data in one event : ~ 1 GByte

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Electronics : ALTRO ~digital oscilloscope Total data in one event : ~ 60 MB (1 MB for p+p)

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Clusters - Position - Width - Max Charge - Total Charge - cells ? 1 cell maximum dimension 5x5

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Result : 3D tracking Test with one cosmic muon trackSimulation of an event in ALICE

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cosmic Test Setting A07 A06 A05 A04 A03 A02 A01 A00 Trigger & - 2 sets of scintillators to trigger on cosmic rays - Only 2 ReadOut Chambers for each run - No Magnetic Field

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cosmic Rays Test Cluster Data Ideas of the analysis  Focus on a few high statistic runs  Cluster data before tracking  Look for all anomalies (noises...) and study them in detail  Clean up the data to study tracks Examples of Results  Noises : Edges, "Ringing noise”  Anomalies : Floating wires in OROC A04

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Edge Noise Events with clusters (when max 159 clusters per track) ! Clusters in a sectorSignal in individual pads gating pulse

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Background Noise : efficient cut - Noise has high frequency, real signal is shaped => small time spread = noise => we remove clusters with σ z <0.035 Now significantly reduced by new grounding and electronics settings σZ2σZ2

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ "Ringing Noise" - Huge amount of clusters in a very localised area - localised in space AND IN TIME ! - periodic pulsations of about 1cm periodicity in time direction z(=time) in cm number of clusters

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Explanation - Present on almost every IROC at same position (probably close to gating grid signal input) - Important enough to produce clusters only on a few - Periodicity coming from remaining 2.5 MHz edge noise Can be uploaded as non-flat pedestal

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Floating Wires on OROC A04 (1) Run 2643 : 1750 V on anode wires Event number pad direction (cm) row number Mean Total Charge in OROC4

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Floating Wires on OROC A04 (2) Mean Total Charge Evolution in OROC4 Event number Row number

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Probable explanation : floating anode wire Gate Anode (~1500V) Cathode (0 V) Row nRow n+1 Row n+2 Electrons trajectories ++

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Probable explanation : floating anode wire Gate Anode (~1500V) Cathode (0 V) Row nRow n+1 Row n+2 Electrons trajectories + +

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Probable explanation : floating anode wire Gate Anode (~1500V) Cathode (0 V) Row nRow n+1 Row n+2 Electrons trajectories

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Clusters in Tracks Cluster Width vs Drift Length Cluster Width vs Track Angle Cluster Charge vs Drift Length

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cluster Width Without magnetic field σ 2 TOT = σ 2 geom + σ 2 diff + σ 2 angle = C 1 + C 2. L + C 3 tan 2 α Diffusion e e Constant drift velocity geometrygas characteristic

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Angular Contribution track α pad effective width of the track

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cluster Width vs Drift Length effect of diffusion expectatio n time width

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cluster Width vs Drift Length Limit : uniform distribution 5 bins limit to the size of the cluster : optimised from 5 MHz sampling, measure at 10 MHz

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cluster Width vs Track Angle expectation s

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Cluster Charge vs Drift Length exponential decrease : expected : 1% per m per ppmO 2 Fit : 5.3 % m -1 saturation effects => upper limit Satisfying result

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Conclusion Corrections done :  new grounding, FEC replaced, software updated Some more tuning needs to be done  reconstruction Other details need more study  how does it behave, how to avoid irrelevant data Some problems in the data identified

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/201641

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Back-up slides

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Hot spots after high freq. noise cut

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Floating Pads : Clusters view

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Floating Pads : Raw Data "Lucky" example : - 4 abnormal pads - signal looks "transferred" to the two extremities... => perhaps floating pads

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Mapping Problem in IROCs

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Mapping Problem in IROCs 1 pad

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Mapping Problem in IROCs 1 track ?? ?

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ General View : noise measurement

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Latest Improved Measurement Additionnal Grounding 4 groups of channels configured to access data memories with 90 0 phase shift

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Random Noise Pads No visible pattern : random noise Track signal visible

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ High Multiplicity Events Shower : visible tracks, many clusters, higher energy Noise (?) : no tracks (strange clusters distribution) normal charge distribution. some cluster have a negative total charge (but no negative max charge) => software problem

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Pad Response : clusters low angle tracks selection horizontal sectors (0&1) Single pads (mostly noise) The pad response and statistics induce a non uniform cluster distribution at the pad size scale 1 pad

Analysis of Cosmic Ray Data from ALICE TPC Philippe GROS 9/29/ Bias created by 2.5 Mhz Noise