1 / 17

MTD Calibration for Cosmic Ray Triggered Data in RUN 10 at STAR

MTD Calibration for Cosmic Ray Triggered Data in RUN 10 at STAR. Lijuan Ruan (BNL), Liang Li (UT Austin) 04/01/2011. Workshop on STAR MTD Production and Related Physics, Hefei, Anhui, China, March 30th - April 1st, 2011 . 1. Motivation.

tieve
Télécharger la présentation

MTD Calibration for Cosmic Ray Triggered Data in RUN 10 at STAR

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. MTD Calibration for Cosmic Ray Triggered Data in RUN 10 at STAR Lijuan Ruan (BNL), Liang Li (UT Austin) 04/01/2011 Workshop on STAR MTD Production and Related Physics, Hefei, Anhui, China, March 30th - April 1st, 2011 1

  2. Motivation • In run year 10 STAR implemented a cosmic ray trigger to study the performance of its several subsystems, including TPC, MTD, TOF etc. • Because the cosmic rays are primarily muons, we were able to get rid of the hadron background from material interactions in the MTD analysis, as seen in previous studies with data from physical collisions. • Also the cosmic ray data offers us significant amount of muon tracks with pt > 2 GeV/c, and these high momentum particles have less interaction with the material than the lower momentum particles therefore we can calculate the tracking information more precisely.

  3. The STAR Detector

  4. Muon Telescope Detector • Since RUN 9 p+p 200 GeV period a new prototype of MTD has been installed outside the STAR magnet steels at a radius ~ 400 cm from the STAR detector center and used to take data at STAR. It is one tray with 3 long MRPC modules and each module has 6 strips. • There are two read-outs for each strip, from the east side and west side respectively. • This prototype utilized the same electronics as that for TOF in order to achieve a better timing resolution than that from trigger electronics.

  5. Data Set RUN 10 Au+Au 11 GeV fastoffline production of st_mtd data stream for Reversed Full Field Selected cosmic ray tiggered events with “cosmic” offline Tigger ID 310803 Global tracks were used 5

  6. QA Plots TOT (ns) Pt (GeV/c) (P1-P2)/P1 Energy Loss 6

  7. Method Zhangbu Xu tMTD is calculated by averaging the times from two ends of an MTD strip so that it does not depend on the hit position on the strip. tTOF1 and tTOF2 are calibrated times associated with TOF hits due to the cosmic ray muons. tTPC is the calculated time of flight between two TOF trays 1 and 2 with the pathlength and momentum information from TPC. tSteel is the time of flight from MTD to TOF, also calculated with TPC information The time difference between TOF+MTD measured time and TPC measured time is deltaT = (tTOF2 – tTPC + tTOF1)/2 – tMTD - tSteel 7

  8. Matching • The matching between 2 halves of a muon track in TPC requires nHitsFit>14, |eta|<1.5 and p>1 GeV/c for each half and |p1-p2|/p1<0.27, where p1 and p2 are the momenta for the two halves. • The next step is raw matching for the TPC tracks. The requirements are nFitPoints >= 25, Pt >= 2.0 GeV/c, TpcZ < 100 cm && TpcZ > (- mrpcLength - 100 cm), TpcPhi > 0.419 && TpcPhi < 0.628, where Z is the position along the beam pipe and an MTD strip, TpcZ and TpcPhi are extroplated Z and Phi values for a track from TPC. • Finally we do the matching between the TPC tracks and the MTD hits, requiring |TpcZ-MtdZ| < 6 cm and |TpcPhi-MtdPhi| < 0.2. MtdZ is from the timing difference between 2 ends of a strip and MtdPhi is from the center of the fired MTD strip.

  9. Position Resolutions deltaPhi Sigma = 0.006 rad deltaZ (cm) Sigma = 2.5 cm 9

  10. TOF Timing Resolution Delta T(ns) deltaT0 = tTOF2- tTOF1 – tTPC TOF timing resolution ~92.9 ps/sqrt(2) ~ 66 ps, close to the result in our intrinsic timing resolution study (M Shao and L Li, International Journal of Modern Physics E, Volume 16, Issue 07-08, pp. 2476-2483 (2007)) The mean value is close to 0 10

  11. The First T0 Offset Correction Delta T(ns) Delta T(ns) First, we did a T0 offset correction for each strip. Basically we fitted the deltaT histograms with a Gaussian function and subtracted the obtained mean value from tMtd. 11

  12. MTD Timing Resolutions By Strip Before Calibration ~196 ps 12

  13. The Slewing Correction Delta T(ns) TOT (ns) Secondly, we combined all channels and plotted deltaT versus averageTOT= sqrt(totMtdEast*totMtdWest). The slewing correction curve is obtained by a 4th order polynomial function fitting the Gaussian mean deltaTs for all averageTOT bins. Then the slewing correction is done by subracting the function value from tMtd according to its averageTOT value. The slewing correction is done for only TOT<22 ns because above that the statistics is poor. 13

  14. The Second T0 Offset Correction A second T0 correction is done thereafter due to the observed T0 shift after the slewing correction Delta T(ns) Delta T(ns) 14 Delta T(ns) Delta T(ns)

  15. Final MTD Timing Resolutions By Strip ~106 ps 15

  16. The Final MTD Timing Resolution MTD+TOF timing resolution: ~109ps Timing resolution from TOF: ~46ps MTD timing resolution: ~99ps 16

  17. Summary • MTD calibration for Au+Au 11 GeV fastoffline production in RUN 10 (RFF) with cosmic ray triggered events is done. • ~109 ps timing resolution for MTD+TOF is achieved, giving ~99 ps for MTD alone. • From this analysis, ~66 ps TOF timing resolution is demonstrated. Thanks! 17

More Related