1 / 22

HBD studies in Run9 200GeV p+p collisions

HBD studies in Run9 200GeV p+p collisions . Jiayin Sun. Two kinds of HBD responses. single electron clusters (SINGLES): One electron per cluster Smaller HBD signal double electron clusters (DOUBLES): two electrons per cluster Larger HBD signal. 4 types of electrons in HBD.

dora
Download Presentation

HBD studies in Run9 200GeV p+p collisions

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. HBD studies inRun9 200GeV p+p collisions Jiayin Sun

  2. Two kinds of HBD responses • single electron clusters (SINGLES): • One electron per cluster • Smaller HBD signal • double electron clusters (DOUBLES): • two electrons per cluster • Larger HBD signal

  3. 4 types of electrons in HBD FAKE SINGLE Type 2 Background : One-legged doubles SINGLE Signal non-phot One electron is not detected. They appear to be singles but are in fact doubles. SINGLE type 0 Background : open pairs DOUBLE type1 background Both electrons are detected by PHENIX

  4. What I did • Search an event for an electron track (normal electron cut) • Get 1st electron • Then look for its HBD cluster ID, charge, size etc. • Search the event again for another electron track (loose cut) • No 2nd electron  single (signal + type2) • Find 2nd electron: • Look for its HBD cluster. • Share same HBD cluster with 1st e  double (type1) • Different HBD cluster  single (signal + type0 + type2) • Real singles and Type 2 are indistinguishable (both appear to be singles: 1 electron/cluster)

  5. Basic HBD cuts • Distance btw track projection & cluster < 4cm • HBD cluster size > 2 pads • Default HBD clusterizer: LBS clusterizer by Ermias. • Ermias’s cut on minimum cluster charge: 15p.e. • To cut out scintillations

  6. Single electron clusters are composed of: signals background: one legged doubles (type2) background: open pairs (type0) 0<pT<1 1<pT<2 2<pT<3 SINGLES HBD charge distribution 3<pT<4 4<pT<5

  7. Double electron clusters are composed of: background: doubles / type 1 clean background. 0<pT<1 1<pT<2 2<pT<3 DOUBLES HBD charge distribution 3<pT<4 4<pT<5

  8. Background: one-legged doubles • Can be constructed from 2-legged doubles (type1), • Define: • R12 = • To get a clean sample of doubles, choose clusters with large charge • Use arbitrary cut at charge > 60 p.e. (justified later) • Assume all clusters > 60 p.e. to be real doubles. Two-legged doubles (type1) Type 2 one-legged doubles (type2)

  9. Background: one-legged doubles singles single && charge >60 Type 1 charge Singles: (Type 2 dominant) Type 1 type Type 1 && charge >60

  10. Construct one-legged doublestype 2 = type1 x (R12)-1 0<pT<1 1<pT<2 2<pT<3 • HBD charge • inclusive singles • type2 • type1 3<pT<4 4<pT<5

  11. Signal after subtraction 0<pT<1 1<pT<2 2<pT<3 • HBD charge • inclusive singles • type2 • open pairs (type0) • (type1) 3<pT<4 4<pT<5

  12. Signal ( 1 < pT < 2) Charge (p.e.)

  13. Results from WIS clusterizer 0<pT<1 1<pT<2 2<pT<3 • HBD charge • inclusive singles • type2 • open pairs (type0) • (type1) 3<pT<4 4<pT<5

  14. Signal ( 1 < pT < 2) (WIS) Charge (p.e.)

  15. HBD charge Cut • Design a cut on HBD cluster charge • Reject electrons with HBD charge > cut value. • Ideally, this cut should: • cut out as many double clusters (photonic electrons) as possible. • Keep as many signal as possible • Keep S/B ratio as high as possible • S/B ratio is a function of the cut. • S/B = signal / (type0+type1+type2)

  16. S/B vs. charge cut 0<pT<1 1<pT<2 2<pT<3 • S/B decline with cut • lower cut: • Cut out a lot of signals • higher cut: • Lower S/B ratio 3<pT<4 4<pT<5

  17. Efficiency vs. charge cut 0<pT<1 1<pT<2 2<pT<3 • Efficiency = • Signals left after cut • Total signals 3<pT<4 4<pT<5

  18. R12 vs. pT(charge > 60 p.e.)

  19. R12 vs. cut at cluster charge 0<pT<1 1<pT<2 2<pT<3 • R12 flat from • 45 p.e. to 65 p.e. • insensitive to the • cut after 45 p.e. • Stat. fluctuation at higher pT 3<pT<4 4<pT<5

  20. Background: open pairs (type0) • Distance betweenclusters • All • 0 < Mee < 0.14GeV • Mee > 0.14GeV • Cut: dist < 10 cm dist SINGLE type 0 Background: open pairs

  21. Background: open pairs (type0) • A look at open pairs dist SINGLE type 0 Background: open pairs mis-associated doubles

More Related