1 / 23

CHORUS Recent Results on Oscillation and Charm Physics

CHORUS Recent Results on Oscillation and Charm Physics. For the collaboration M. Guler Middle East Technical University, Ankara. Neutrino beam. West Area Neutrino Facility at CERN SPS. 450 GeV. CHORUS, NOMAD. W ide B and B eam 5.06  10 19 POTs (1994-1997)

genevieve-horne
Download Presentation

CHORUS Recent Results on Oscillation and Charm Physics

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. CHORUS Recent Results on Oscillation and Charm Physics For thecollaboration M. Guler Middle East Technical University, Ankara

  2. Neutrino beam West Area Neutrino Facility at CERN SPS 450 GeV CHORUS, NOMAD Wide Band Beam • 5.06  1019 POTs (1994-1997) • <Enm> ~ 27 GeV • <L> ~ 0.6 km • Prompt nt : negligible <L>/<E> ~ 2  10-2 km/GeV  Dm2 > 1 eV2

  3. CHORUS detector T=5° Nucl. Instr. Meth A 401 (1997) 7 - Calorimeter h- 770 kg emulsion target and scintillating fibre tracker Muon spectrometer Air core spectrometer and emulsion tracker Veto plane

  4. Nuclear emulsion yesterday • 3-d spatial resolution better than1 m Discovery of pion • 1947, first nuclear emulsions. Lattes et al., Brown et al.:

  5. CHORUS automatic microscopes New Track Selector CCD and XYZ stage Host CPU Network data storage

  6. Automatic Scanning: The Track Selector (TS) track shifting track Found track summing

  7. CHORUS Phase II • New EMULSION data-taking and analysis for • Increased sensitivity oscillation search • Charm physics • PRINCIPLES: • Multi-track predictions (and Scanback) without kinematical cuts • Full vertex emulsion data taking (on located vertices) • Offline Emulsion Analysis

  8. Oscillation Analysis • Decay mode considered i)-t - m- nmnt ii)- t - h-(np0)nt , iii)- t-  3h-(np0)nt • Pre-selection (data from electronic detector) -vertex predicted in the emulsion -At least one negative track -1m sample -0m sample • Emulsion Scanning -Scan back of selected tracks CSSSbulkvertex plate -Vertex reconstruction & decay Search, NETSCAN -Event selection -Eye-Scan Check, visible recoil, blob or Auger electron • Final kinematical cuts -decay length, kink angle, Pt at vertex

  9. Automatic vertex location scan-back track • Follow up the track, plate by plate to vertex • 100 mm most upstream part of each target plate are scanned • Vertex plate defined by the first plate out of two consecutive plates where track segmentis not found.

  10. Offline Emulsion Analysis 1 2 Location of n interaction vertex guided by electronic detector. 1 2 Full data taking around n interaction vertex called NETSCAN 3 Offline tracking and vertex reconstruction Reconstruct full vertex topology At least 2-segment connected tracks Track segments from 8 plates overlapped Eliminate passing through tracks

  11. CHORUS Background • Definition: 1-prong nuclear interactions with no heavily ionizing tracks or other evidence for nuclear breakup in thethadronic decays. • Poor previous knowledge oflWK(P, Pt). Difficult to extrapolate (sensitive to the operative definition of “whiteness”) • MC development to tune the cuts against the WK background • Fluka to model the hadron interactions in emulsion • Cuts to reproduce the minimum observable activity (the white-gray transition) in the Chorus emulsions

  12. Data flow Triger 2,305K 1mu 0mu Initial sample 713,000 335,000 Events scanned 335,395 85,211 Events located 143,742 24,184 Events selected 11,398 1082 • After cuts : 0 candidates

  13. Status of oscillation intont nm – nt ne – nt NOMAD data: final - CHORUS phase-II is not yet finished

  14. I.P. Detector muon Measurement of D0 production • Candidate selection • Primary track matched to detector muon • Daughter track matched to detector track • 3 ~ 13 μm < I.P. wrt. 1ry vtx < 400 μm • Confirmed D0sample • 2 prong (V2) 841 (background: 35) • 4 prong (V4) 230 (no background) • Selection efficiencies (D0 V4 ) / ( D0 V2) = 21.8 ± 1.6 x 10-2 • V2 : 56.3 ± 0.5 x 10-2 • V4 : 74.2 ± 0.9 x 10-2 • BG subtracted, efficiency corrected • V2 1426 ± 52 • V4 310 ± 20

  15. Fully neutral D0 decay modes Preliminary BR4/BR2 – measured BR4 = 0.1338 ± 0.0058 PDG BR(D0 neutrals)=1-BR4 x(1+ BR2/BR4)=24.1 ± 4.5%(V6 negligible) Total production cross section All D0’s = NV4/BR4 = 2280 ± 151(stat.) ± 26(stat.eff.) ± 99(BR4 err.) Relative detection efficiency D0/CC = 0.88 σ(D0)/σ(CC) = 2280/95450/0.88 = = 2.71 ± 0.22 x 10-2

  16. – D+D+X   – D+D+X Z c g – c c c Associated charm production In CC interaction In NC interaction Gluon bremsstrahlung Gluon bremsstrahlung & Z-gluon fusion  m W g • In the past only one event • Observed in E531 emulsion • Indirect search performed by NuTeV • Production rate (2.6±1.6)x10-3of CC One event has been observed and published Phys. Lett B 539 (2002) 188

  17. n beam (Event: 8132 12312) -640 mm, pl 23 -600 mm, pl 22 -704 mm, Pl 23 n int. V2 V2 -700 mm, Pl 23 -600 mm, Pl 23 -588 mm, pl 22 CCbar candidate

  18. N= 4374 ± 135 fCo fC- (N +cX) + 1.9 + 1.2 = 2.9 (stat) = 4.8 % (N +X) - 1.2 - 0.9 Charm production in antineutrino interactions Energy dependence N+ = 2725 N- = 93890 Selected events = 82 found charm = 61 after  reconstruction cut = 32 Preliminary

  19. Measurement of D0 momentum Use correlation between opening angle of decay daughters and charm momentum to obtain momentum distribution Inverse of geometrical mean of opening angle of daughters D0 Momentum Momentum distribution of D0 can be measured by unfolding opening angle distribution (curve is the model in the CHORUS MC) D0 Momentum

  20. Z & X-Feynman distributions Preliminary Peterson formula Collins-Spiller • Also an E531 measurement • Indirect measurements from dimuon data: • CDHS, CCFR, CHARMII, NuTeV, CHORUS

  21. Charm fragmentation results Preliminary Large spread in values May be due to different mixtures of charm final states: • E531: all charm decays • Nomad: D* • CHORUS: D0 • Dimuon experiments: weighted by muonic decay mode

  22. Conclusion I • Emulsion scanning is completed. • Estimate the efficiencies & tune the cuts. • Final oscillation result is before the end of year.

  23. Conclusion II So far, we have measured: Phys. Lett. B. 596 (2004) 44 Phys. Lett. B. 555 (2003) 156 Phys. Lett. B. 575 (2003) 198 Phys. Lett. B. 527 (2002) 173 Phys. Lett. B. 539 (2002) 188 Phys. Lett. B. 549 (2002) 48 Phys. Lett. B. 435 (1998) 458 • Trimuon events • Λc production • QE charm production • D0 production • CC associate charm production • BR   • Diffractive Ds* production We are studying : • D0 decay in neutrals • D* D0 + + • Associated charm production in CC and NC • Charm fragmentation function • Anti-neutrino charm production • x distribution • Vcd

More Related