1 / 17

EMC update

This update covers the status of EMC analysis, calibration, transverse energy measurement, electron identification, and p0 spectrum in proton-proton and heavy-ion runs at Wayne State University. The report includes online monitoring, EMC simulations, and plans for forthcoming runs, detailing tower instrumentations, trigger mechanisms, and data collection methodologies. Specific topics such as electron calibration, transverse energy analysis, and p0 reconstruction techniques are also discussed. The text touches on data processing procedures, systematic errors reduction, simulations, and common mDST practices in the field. Ongoing physics research, including hadronic energy subtraction, track isolation, and particle reconstruction strategies, is presented. The collaboration with Steve Trentalange, Dylan Thein, and Alex Stolpovsky in p0 spectrum studies is highlighted, with a focus on trigger efficiency improvements and background corrections. Looking ahead, the implementation of online calibration and quality assurance tools, as well as the importance of EMC simulations and common mDST data storage, are emphasized for future research endeavors in high-energy physics.

latonia
Download Presentation

EMC update

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. EMC update • Status of EMC analysis • Calibration • Transverse energy • Electron identification • p0 spectrum in pp • Plans for the next run • Online monitoring and calibration • EMC simulations • EMC on common mDST Alexandre A. P. Suaide Wayne State University

  2. Just to remember … • Heavy-ion run • 12 (10) modules instrumented • 480 (~400) towers • (Dh, Df) ~ (1.0, 1.2) • No SMD most of time • Last week of HI only • pp run • 22 (16) modules instrumented • 880 (~640) towers • (Dh, Df) ~ (1.0, 2.2) • SMD • High-tower trigger Alexandre A. P. Suaide Wayne State University

  3. AuAu pre-calibration using MIP’s • AuAu data • Towers equalized within 5% • 200 k minibias data • MIP candidates • p>1.5 GeV/c • Track isolated in a 3x3 patch 500 ADC ~ 4 GeV Alexandre A. P. Suaide Wayne State University

  4. Electron identification in STAR • TPC information • Momentum of the track • dE/dX • For electron selection • For hadronic background estimation • Number of dE/dX points • EMC information • Distance from the projected track to the center of an EMC tower • Energy of the tower • Dataset • Minimum bias AuAu • ~ 2 M events • Central AuAu • ~ 150 k events • |zvertex| < 20 cm Alexandre A. P. Suaide Wayne State University

  5. EMC information (towers only) • p/E cut • distance to the center of the tower cut • Hadronic background estimation • Hadronic suppression factor ~ 20 for efficiency ~ 0.5 Alexandre A. P. Suaide Wayne State University

  6. Electron calibration • Initial calibration done with MIP • ~10% systematic errors • low energy (~300 MeV) • Electron calibration • Higher energy (1.5 – 5 GeV) • Reduce systematic errors to 2-3% • EMC global energy resolution • ~17%/sqrt(E) Alexandre A. P. Suaide Wayne State University

  7. Putting all results together (TPC + EMC) Minimum bias AuAu Alexandre A. P. Suaide Wayne State University

  8. Physics going on… Transverse energy Marcia • Transverse energy analysis • Electromagnetic transverse energy • Use TPC tracks to subtract hadronic energy deposited on EMC • Hadronic transverse energy from TPC • Finalizing systematic errors Alexandre A. P. Suaide Wayne State University

  9. Steve Trentalange Dylan Thein and Alex Stolpovsky p0 reconstruction (invariant mass spectra) • p0 reconstruction with pp data • SMD present • Still needs better understanding of uniformity and gain • High tower trigger • Improve statistics • Low EMC occupancy • Smaller background Alexandre A. P. Suaide Wayne State University

  10. Steve Trentalange Dylan Thein and Alex Stolpovsky p0 spectrum • High tower trigger • A lot of corrections still to be done (trigger bias, efficiencies, etc) • Only 10% of full EMC acceptance • Corrections are still being studied Preliminary Alexandre A. P. Suaide Wayne State University

  11. EMC for the next run - online • Online Calibration and QA • Pedestals • Towers pedestal will be calculated on the fly from the data • No special run is required • Auto update to STAR DB for offline reconstruction • SMD pedestal subtraction at DAQ? • No zero suppression • Gain equalization and gain monitoring • Auto update to offline DB with gain variations • MIP and electron calibration • Get events from event pool • Need L3 tracks • Fit of MIP and electron peaks will be done offline • Estimated time to have first calibration – 2 weeks after beam starts • QA histograms • Global histograms to single tower spectrum are available Alexandre A. P. Suaide Wayne State University

  12. EMC Simulations • EMC slow simulator in place • It is ready for real simulation • calibration • pedestals and noise • dead channels • Only issue is database timestamp • Now -> one timestamp for all STAR ???? • Works fine with real data because event time is the same • What to do in plain simulations? Which timestamp? • Different detectors -> diff configuration -> diff timestamps • Embedding • Just to merge hits (add ADCs) and run EMC reco again • Can be done at analysis level. • Does not need special chain Alexandre A. P. Suaide Wayne State University

  13. EMC on common mDST • What do we need to save? • All tower hits (ENERGY and ADC) • SMD hits above threshold (ENERGY and ADC) • Clusters and points • Current EMC micro DST • 9 bytes/hit • 42 k (towers) (FIXED) + ~ 2 k (SMD) • 20 bytes/cluster • ~ 0.7 k/event • 24 bytes/point • ~ 0.4 k/event • Some features we want to keep • Re-creation of StEvent (limited version) • What do we need? • Basic event structure (trigger, vertex, etc) • Basic tracks (Geometry, dE/dX, etc) • StEmcCollection • And, why do we need? • EMC clustering and point thresholds depend on physics • Cluster finder and point maker are StEvent compatible • Reconstruction of clusters and points at analysis level for more sophisticated analysis Alexandre A. P. Suaide Wayne State University

  14. EMC on common mDST • Thinking a little bit WITHOUT cutting the data • Can change hit definition for tower • TObject* -> Float_t (ENERGY) and Short_t (ADC) arrays • 42 k/event -> 28 k/event • TObject* -> char[10200] for energy and char[7200] for ADC • Pack energy in a 17 bits value • Energy measurement from 0 to 131 GeV with resolution of 1 MeV • Pack ADC’s in a 12 bits value • Same resolution as DAQ • 42 k/event -> 17 k/event • Not the best solution for last year data because patch was small • Keep the old hit definition for SMD • 9 bytes/hit Alexandre A. P. Suaide Wayne State University

  15. Do we need to save all tower hits? • EMC is a calorimeter, not a tracking detector • Proper energy measurement is fundamental • Electron, photon reconstruction • Jet reconstruction • Et, etc • What happens if we cut tower hits bellow some threshold? • Total energy measurement (Et) is biased • Shift on mass and momentum of reconstructed electromagnetic particles • Wrong jet energy Alexandre A. P. Suaide Wayne State University

  16. Just one example: Transverse energy • Et is calculated assuming different energy cuts and compared to full energy measurement • Stronger BIAS in the low multiplicity region. • This is the region where the size makes difference and we completely screw up the EMC measurement Alexandre A. P. Suaide Wayne State University

  17. Final comments • EMC Analysis • Transverse energy just coming out • Electrons and p0’s can be identified • p0 spectrum up to ~6.5 GeV/c for pp? • EMC for the next run • Online QA and Calibrations • EMC simulator • Ready for real detector simulation • Embedding is not an issue • Need to learn how to deal with timestamp • EMC on micro DST • Very important for next year • Event size seems to be an issue now. • Need to save all tower hits Alexandre A. P. Suaide Wayne State University

More Related