1 / 41

Measurement of the φ -meson production in the RHI Collisions with the PHENIX detector at RHIC

Measurement of the φ -meson production in the RHI Collisions with the PHENIX detector at RHIC. Sasha Milov Weizmann Institute of Science for the PHENIX Collaboration. Part I. Analysis. Data samples. Published:   arXiv:1005.3674 arXiv:1004.3532 Phys. Rev. Lett. 99, 052301 (2007)

tyne
Download Presentation

Measurement of the φ -meson production in the RHI Collisions with the PHENIX detector at RHIC

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. Measurement of the φ-meson production in the RHI Collisions with the PHENIX detector at RHIC Sasha Milov Weizmann Institute of Science for the PHENIX Collaboration

  2. Part I. Analysis

  3. Data samples Published:   arXiv:1005.3674 arXiv:1004.3532 Phys. Rev. Lett. 99, 052301 (2007) Phys. Rev. C 72, 014903 (2005) Preliminary M. Naglis, Φ meson production in p+p, d+Au and Au+Au collisions at RHIC using the PHENIX detector. PhD thesis, WIS, 2009. D. Sharma, - and φ-meson production in p+pand d+Au collisions at RHIC energies, using the PHENIX Detector. PhD thesis, WIS, 2010. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  4. K+K– mode • ToF-ToF configuration: • Provides the cleanest sample, but is limited both in acceptance an in momentum. • ToF-EMCToF configuration: • This configuration was used only in run2 analysis because it is limited in pT of the particles. • ToF-noPID configuration: • Provides larger acceptance on expense of worse S/B ratio, but increases overall significance and momentum reach • noPID+ matching: • Allows cleaning the sample and make systematic studies • noPID-noPID configuration: • Getting even larger acceptance Central arm acceptance: || < 0.35Δ = 2 x 90o Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  5. K+K– mode K+ K– (two K ID) Peak examples are shown for p+p data at √s=200GeV Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  6. e+e– mode • Tracking: • Use of both arms and two arms decays to increase statistics and low pT coverage. • Electron Identification: • RICH + EMCal (both technologies) to increase coverage and reduce systematic errors. • Combinatorial Background Subtraction: • Based on mixing technique using pairs from different events. Events must be similar in vertex and centrality. • Dalitz pair rejection: • Not yet used, but will be possible with HBD data from runs 2009, 2010. Central arm acceptance: || < 0.35Δ = 2 x 90o Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  7. Electron identification Efficiency Purity Mass corresponding to the beam-pipe radius EMCal e/π=10 RICH e/π=1000 Upper curve: pairs from where only one track is identified as e+ or e– coming fromDalitzes and conversions Middle curve: pairs open up in the plane orthogonal to magnetic field (remove Dalitzes) Lower curve: Pairs where the second track was not identified as an electron. Upper curve: all tracks Middle curve: e+e– identified by RICH Lower curve: Random coincidence. E/p cut increases electron sample purity by additional factor of 10. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  8. Combinatorial background M e+e– M e+e+ M e–e– Event Ne– Ne+ M e+e– M e+e+ M e–e– Pool of electrons from same event category: centrality, reaction plane, vertex Subtraction Normalization e– e+ e– e+ π0 γe+e– γ  e+e– e– e+ <N±> = 2√<N++><N– –> e– Combinatorial Background Subtraction: PRC81, 034911 (2010) Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  9. e+e– mode Au+Au d+Au p+p • In p+p: • Combinatorial Background Subtraction was not used, because the S/B ration is relatively high ~ 5:1. • In d+Au: • C.B.S. was used for MB trigger only. For ERT the mixing was done for MB and ERT condition was imposed on it. S/B varies from 10:1 to 1:10 (approx.) • In Au+Au: • C.B.S. is the only way to estimate the signal. S/B ration is very low < 1:100 • Under the peaks: • Correlated background. “The Cocktail” Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  10. Efficiencies • Acceptance: • Includes geometry, inactive regions, detector response, analysis cuts. • Trigger efficiency to a triggering (daughter) particle: • Measured from MB sample, includes trigger electronics inactive areas • Trigger efficiency to the analyzed (mother) particle: • Deduced from the MC and the single particle trigger efficiency. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  11. μ+μ–mode Muonarm acceptances: -2.4< < -1.2 1.2< < 2.2 Δ = 2π • Sample : • So far run8 (d+Au) • p+p sample also very promicing • Muon arms: • Use acceptance of both muon arms. • CBS: • The sample is biased therefore use of CBS is difficult. We used modified method of the CBS • Clear signal form φ and /. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  12. Part IIa. Results (Spectral widths shapes and yields)

  13. Line shape modification • Chiral Symmetry Restoration probe: • Due to its short life-time (44 fm/c), the φ is considered a probe of the Chiral Symmetry Restoration • The line shaper and/or position of the particle can be different from the vacuum value. • The effect is expected to be seen in: • The most central AuAu collisions • At low pT. • In di-lepton channel • The data is measured in: • The MB AuAu collisions • At average pT • In hadronic channel • I do not have results on e+e– in p+p • But one does not expect large signal there Phys. Rev., C63 (2001) 054907 Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  14. p+p spectra @ 200 GeV • Consistency: • An agreement between different K-ID methods was shown before • K+K– and e+e– results very well agree to each other • Momentum coverage: • e+e– mode allows measurement at zero pT, thus providing the integrated yield. • K+K– mode w/o identification extends to 7 GeV/c, limited by statistics. • Self-consistent result in a wide pT range from 0.125 to 7 GeV/c Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  15. Integrated Yields in p+p @ 200GeV • arXiv:1005.3674 • dN/dy and <pT>: • First time direct counting of the integrated parameters, no extrapolations or model assumptions • PHENIX / STAR: • The numbers are close between the experiments, which is not always the case… • Statistical model agreement: • Not clear why the stat. model works in p+p, but it does a good job. • Stat model calculation from EPJC66, 377 (2010) • dN/dy and <pT> of φ-meson are directly measured in p+p Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  16. A+A @ 200 GeV in K+K– • Spectra in A+A: • Measured above 1GeV/c in full range of centralities and systems. • Fits well to Tsallis function, and departs from exponential. • High pT: • The departures depends on species and centralities. Consistent with recombination models. • Low pT: • No significant change in slope. Support an expectation of a lesser radial flow for φ-meson. • PHENIX provides full set of measurements @ 200 GeV in K+K– Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  17. d(Au)+Au @ 200 GeV in e+e– • d+Au: • Covering the entire pT range form zero to 6 GeV/c in all centrality bins. • Au+Au: • The run4 Preliminary data which is of a lesser stat. significance compare to hadronic channel. It will remain so before the HBD results are analyzed. The lighter systems are measured. The analysis of AuAu data required HBD samples to be analyzed. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  18. Integrated Yields in A(d)+A @200GeV • Integrated parameters: • Due to pT range in K+K– mode the integrated values require assumptions to work them out • In e+e– the result suffers from extremely poor statistics and shall be taken seriously only with the systematic errors. • The slope parameter: • T changes very little with increasing Npart but clearly depends on √sNN • The yield per participant: • Clear increase from p+p to central AuAu in both measured energies. • @200GeV the increase is approximately by a factor of 3 • Yields increase with Npart. Slopes remain the same. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  19. Spectra @ 62GeV • Spectra: • PHENIX has Preliminary results on φ-meson production measured in K+K– decay channel at 62 GeV in p+p, CuCu and AuAu systems. • Measurements are done above 1GeV/c and extends to 3-4GeV/c limited by available statistics. • The results exist in full range of centralities and systems. • Full set of data to study the systematics of the φ at lower energy. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  20. Part IIb. Not about physics…

  21. A factor of 2. • Integrated yield in p+p: • Perhaps the only measurement where PHENIX and STAR agree. • Spectra in all systems: • Consistently show higher rates measured by STAR reaching a factor of 2 for the same number of participants in Au+Au. • Ratios: • Yet the ratios to p+p like RAA and dN/dy look more or less the same. Compiled by M.Naglis PHENIX takes it very seriously. With a variety of samples, decay modes and techniques, we give the φ-meson “a very special treatment”. We hope STAR does the same. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  22. Part IIc. Results (Flow)

  23. Flow • Results: • PHENIX published results of run4 and has preliminary analysis of run7 flow of φ-meson in AuAuat 200 GeV. • The results are consistent. • Scaling: • Elliptic flow v2 of the φ-meson scales with the number of quarks the vs. kET/q similar to the scaling observed for all the measured particles. • Flow of the φ is crucial for establishing the validity of the flow scaling with the number of quarks. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  24. Part IIc. Results (Nuclear Modification Factor)

  25. RdA @ 200 GeV • Run3: • Preliminary PHENIX results left room for some increase of the RdA at high pT. Although the data was also consistent with the flat behavior the trend was suggestive. • Run8: • Final results published by PHENIX show no increase. • The new results extend to 7 GeV/c and above 1 GeV/c the behavior of φ-meson is consistent with the trends shown by other mesons. Cold Nuclear Matter effects in φ-meson production @ 200 GeVare weak if any. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  26. RdA @ 200 GeV Au d First look: φ is suppressed in d-going direction, In Au-going direction the ration is constant like at mid-rapidity (we are looking at rather high-pT) The result is new and promising, work on it continues. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  27. Cu+Cu @ 200 & 62 GeV RAA in CuCu and AuAu shows similar suppression for close Npart The same behavior is measured for all other particles in these systems Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  28. Almost a summary • At mid-rapidity, in all decay modes, in all systems, at all energies, in all parameters we measured: • K+K–, e+e– • p+p, d+Au, Cu+Cu, Au+Au • 62 GeV, 200 GeV • RAA, flow • the φ-meson behaves consistently with all other mesons in the full pT range of our measurements. • The values seems to show different behavior are the integrated yields per participant, significantly increasing from p+p to the most central Au+Au events. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  29. RAA @ 200 GeV • In the most central: • At pT <2GeV/c suppression of φ are K similar suggesting the flavor content dependence. • The difference grows even more, however >5GeV/c the RAA’s are comparable at present statistics. • That however is in contradiction to the -meson trend which has ~50% strange quark content and behaves similar to π0 • Closer to central: • The difference between the two particles grows up at intermediate pT’s. • In the most peripheral: • φ shows no enhancement, however it is not suppressed by ~0.8 like π0 φ-meson suppression is far from being understood. We need low and high pT data and other s-quark particles to complete the picture. Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  30. Part III. Instead of a summary

  31. BACKUP

  32. Nuclear Modification Factor Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  33. HBD peaks Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  34. Part I. Detector

  35. The PHENIX detector Pioneering High Energy Nuclear Interaction eXperiment • Magnetic Field: • Outer coils: • ∫Bdl = 0.78 Tm • Polarity can change for systematic studies and field configuration with Inner coil. • Inner coil: • “+ +” mode ∫Bdl = 1.04 Tm • Increase in tracking resolution • “+ –” mode ∫Bdl = 0.43 Tm • Creating zero-field region Central arm acceptance: || < 0.35Δ = 2 x 90o Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  36. The PHENIX detector Pioneering High Energy Nuclear Interaction eXperiment • Global detectors: • BBC / ZDC: trigger, vertex, timing, centrality. • εtrigger = 50%… 92% • σvertex = 0.5cm… 2cm • Tracking System: • DC / PC1: momentum, pattern recognition. • dpT/pT ≈ 1.0%•pT + 0.7% • Pattern recognition: • DC / PC1 + PC2 + PC3/EMCal: events structure, fake rejection • εoccupancy = 100%… 85% • Calorimetry: • PbSc / PbGl: EM component, • σE/E ≈ 8.1%/√E + 3.0% Central arm acceptance: || < 0.35Δ = 2 x 90o Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  37. The PHENIX detector Pioneering High Energy Nuclear Interaction eXperiment • Time of Flight: • Scintillating slabs: • p/K < 4.5 GeV/c • π/K < 2.5 GeV/c • σToF≈ 100 ps • Calorimetry: • PbSc: ToF • σToF≈ 500 ps • PbSc/PbGl: Shower shape, E/p • eID: • RICH PMT/CO2: • e/π > 1000 • Other (not used) • RPC ToF • Aerogel • HBD Central arm acceptance: || < 0.35Δ = 2 x 90o Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

  38. The PHENIX detector Pioneering High Energy Nuclear Interaction eXperiment • Triggers: • Minimum Biased: • 1 or more hits on each side • ERT gamma: • ∑2x2(4x4) EMCal towers must exceed threshold • ERT electron: • The same in coincidence with RICH hit Central arm acceptance: || < 0.35Δ = 2 x 90o Sasha Milov, WISH-2010, Catania: "Measurement of φ..." Aug,10,2010

More Related