1 / 38

Dielectron Spectroscopy at SIS-18 Energies

This conference will focus on the microscopic structure of dense matter and in-medium spectral functions through the study of dilepton decays of vector mesons. The event will also explore appropriate models to relate microscopic properties to observables in the context of quark-gluon plasma.

gilbertcarter
Télécharger la présentation

Dielectron Spectroscopy at SIS-18 Energies

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. International School of Nuclear Physics Erice 16-24 September 2008 Dielectron Spectroscopy at SIS-18 Energies Joachim Stroth NuclearPhysics Institute, Goethe-University Frankfurt and GSI

  2. Motivation • At 1-2 GeV/u (Au-Au) long lifetime of the dense system: • Dt (3 > r/r0 > 2) @ 15 fm/c >> tRho • Dilepton decays of vector mesons extremely rare probe: • Pee<10-7/collisions • What is the microscopic structure of this matter • In-medium spectral functions • What are the appropriate models to relate the microscopic properties to observables QGP SPS SIS-100 SIS-300 RHIC AGS hadrons <qqbar> B.J. Schäfer, J. Wambach priv. communication SIS-18 Chemical Freeze-out: A. Andronic, PBM, J. Stachel et al.; Cleymans, K. Redlich et al. Joachim Stroth

  3. Dielectron Spectroscopy at the Bevalac The puzzle ! Observed excess remained unexplained over years Calculation:E.L.Bratkovskaya et al. Phys. Lett. B445 (1999) 265 Calculation: Ernst et al. Phys. Rev. C58 (1998) 447 Calculation: C. Fuchs et al. Phys. Rev. C68(2003) 014904 1 AGeV Joachim Stroth

  4. Spectrometer concept Spectrometer with large acceptance and high rate capability. Demanding: • Strong magnetic field over large volume but with field free region around the target • Compact RICH with sufficient number of UV photons per ring • Fast tracking system with high granularity and minimal material budget • Real-time trigger on electron candidates by pattern recognition 1994: Funding approved 2001: Commissioning 6 years of R&D and construction 2002: First production run 1 m Joachim Stroth

  5. Joachim Stroth

  6. Electron Identification DATA • Spatial correlation : • Ring center - Track • Track - META hit • Velocity condition • Shower condition • For p > 500 GeV/c C + C @ 2AGeV e+ e- hadron admixture < 5% (p>1000 MeV/c)! Joachim Stroth

  7. The DLS Puzzle Joachim Stroth

  8. Reconstruction of the signal • Not corrected for acceptance and efficiency • Normalized to the number of produced p0 (Nπo = ½ (Nπ- + Nπ+)) • Comb. Background (CB) Mee < 150 MeV/c2Like-sign pairs Mee > 150 MeV/c2event mixing • Signal: • S+- < 150 MeV/c2: ~17780 counts • S+-≥ 150 MeV/c2: ~ 646 counts Joachim Stroth

  9. C-C @ 1 GeV/u: Dielectron yield • PLUTO Cocktail: • Experimental data • mt scaling where not available Cocktail A:0+ η + ω“long lived components“ Cocktail B: Cocktail A + Δ + ρ Data: HADES collaboration, Phys. Lett. B 663 (2008) 43-48 PLUTO (Monte Carlo Simulation Tool for Hadron Physics): I. Froehlich et al. , arXiv:0708.2382 Large excess above cocktail! Joachim Stroth

  10. HADES and DLS Phase Space Coverage HADES DLS mid-rapidity mid-rapidity For a comparison of HADES and DLS results the HADES yield has to be extrapolated to full phase space. Joachim Stroth

  11. Direct Comparison Remaining uncertainties due to extrapolation into the p-Dalitz region (blue and cyan triangles). DLS Data: R.J. Porter et al.: Phys. Rev. Lett. 79(97)1229 J. Carroll – presentation International Workshop on Soft Dilepton Production August 20-22,1997, LBNL HADES and DLS data agree ! Joachim Stroth

  12. C-C @ 2 GeV/u: Dielectron Yield and Cocktail Cocktail A:0+ η + ω“long lived components“ Cocktail B: Cocktail A + Δ + ρ HADES collaboration, Phys. Rev. Lett. 98, 052302 (2007) Joachim Stroth

  13. A closer look to the excess yield • At SIS energies effectively all pions come from resonance decay (regeneration). Excess yield scales like 0 ! Hadron data R. Averbeck et al., TAPS coll., Z. Phys. A 359, 65 (1997) R. Holzmann et al., TAPS coll., Phys. Rev. C 56, R2920 (1997) Joachim Stroth

  14. New transport results: HSD • New treatment of Bremsstrahlung in HSD! • Off-shell transport • Time integration method • Based on results of a OBE calculation by Kaptari & Kämpfer • pn Bremsstrahlung larger by a factor 4 compared to what was used in transport before • Incoherent treatment • Elastic: soft photon approximation • Inelastic: Explicit Resonance propagation and decay E. Bratkovskaya and W. Cassing,, Nucl.Phys.A807:214 250,2008 L.P. Kaptari and B. Kämpfer, Nucl. Phys. A 764 (2006) 338 Joachim Stroth

  15. ElementaryReactions FW 2 m deuteron beam spectator proton 7 m Joachim Stroth

  16. Exclusive reconstruction of the p,h  ge+e- PLUTO: resonance model! • Teis et al, ZPA356 (97) 421 • D angular distrib. from Dmitriev et al, NPA459 (86) 503 • N 1440 ang. distr. from Aichelin, priv. comm. • D decay angle varied from 1+0.6cos² (Wicklund et al. PRD 35 (87) 2670) to 1-3cos² D1223 N1440 N1535 D1600 Joachim Stroth

  17. Inclusive Dielectron Production Strong isospin dependence! Joachim Stroth

  18. Inclusive Dielectron Production & HSD preliminary preliminary Joachim Stroth

  19. Bremsstrahlung in p-p and n-p collisions g* N N N N N N N N N N N N g* R g* VM R h contribution is taken out. Joachim Stroth

  20. Comparison of C-C and elementary collisions • C-C yield can be explained by properly scaling p-p and d-p results. • No sensitivity on transverse momentum of spectator proton preliminary No evidence for “medium effects” in C-C collisions Joachim Stroth

  21. Vector Mesons Joachim Stroth

  22. Vector meson production in p-p at 3.5 GeV Preliminary (not efficiency corrected, no normalization) • e+e(tot~20 nb! ) •  ~ 35 MeV/c2 • reference for p+A (2008) • Yield excess below / : Mass resolution in the w region < 2,7 % extended VDM? Ch. Fuchs et al., Phys. Rev. C68(2003) 014904 Cocktail: meson multiplicity from HSD 0//(,)= 0.46/0.031/0.011 (meson/inelastic) Joachim Stroth

  23. Ar-KCl 1.75 GeV/u • Preliminary efficiency correction. • Still uncertainty in absolute normalization with respect to the cocktail (< factor 2). • Strong excess in mass region M > 0.5 MeV/c2. • Cocktail: PLUTO First w signal in HI collisions at SIS-18 energies Joachim Stroth

  24. The HADES upgrade project • Cope with multiplicities of Au+Au 1.5 AGeV • Accept up to 20 KHz trigger rate • Measures: • Replace TOFINO with high-granularity RPC • Add forward hodoscope • Upgrade DAQ (new Trigger and Read-out Board) • Extend RICH radiator • Replace plane I tracking chambers • RPC full size prototype successfully commissioned in November 2007. • Expected resolution below 80 ps. 85.1 ps 74.9 ps Joachim Stroth

  25. Summary First round of data taking (almost) finished  upgrade in 2009! • C-C @1 and 2 GeV/u • Excess yield above long-lived components established • Can be fully attributed to contributions from NN scattering – no “medium effects” • p-p 1.25, 2.2, 3.5 GeV, d-p 1.25 GeV/u • Strong isospin effect in e+e- from NN scattering • Elastic or inelastic Bremsstrahlung (D,N* Dalitz)? • Ar+KCl 1.76 GeV/u • w signal in e+e- decay channel observed • K+, K- ,K0, f, L and X reconstructed -> go to SQM 2008 • p-Nb 3.5 GeV (running just now) • Is there a w mass shift or broadening • Bright future • Au+Au, p-induced a SIS-18 and later A+A at SIS-100 Joachim Stroth

  26. G. Agakishiev8, C. Agodi1, A. Balanda3,e, G. Bellia1,a, D. Belver15, A. Belyaev6, A. Blanco2, M. Böhmer11, J. L. Boyard13, P. Braun-Munzinger4, P. Cabanelas15, E. Castro15, S. Chernenko6, T. Christ11, M. Destefanis8, J. Díaz16, F. Dohrmann5, A. Dybczak3, T. Eberl11, L. Fabbietti11, O. Fateev6, P. Finocchiaro1, P. Fonte2,b, J. Friese11, I. Fröhlich7, T. Galatyuk4, J. A. Garzón15, R. Gernhäuser11, A. Gil16, C. Gilardi8, M. Golubeva10, D. González-Díaz4, E. Grosse5,c, F. Guber10, M. Heilmann7, T. Hennino13, R. Holzmann4, A. Ierusalimov6, I. Iori9,d, A. Ivashkin10, M. Jurkovic11, B. Kämpfer5, K. Kanaki5, T. Karavicheva10, D. Kirschner8, I. Koenig4, W. Koenig4, B. W. Kolb4, R. Kotte5, A. Kozuch3,e, A. Krása14, F. Krizek14, R. Krücken11, W. Kühn8, A. Kugler14, A. Kurepin10, J. Lamas-Valverde15, S. Lang4, J. S. Lange8, K. Lapidus10, L. Lopes2, M. Lorenz7, L. Maier11, A. Mangiarotti2, J. Marín15, J. Markert7, V. Metag8, J. Micel7, B. Michalska3, D. Mishra8, E. Morinière13, J. Mousa12, C. Müntz7, L. Naumann5, R. Novotny8, J. Otwinowski3, Y. C. Pachmayer7, M. Palka4, Y. Parpottas12, V. Pechenov8, O. Pechenova8, T. Pérez Cavalcanti8, J. Pietraszko4, W. Przygoda3,e, B. Ramstein13, A. Reshetin10, M. Roy-Stephan13, A. Rustamov4, A. Sadovsky10, B. Sailer11, P. Salabura3, A. Schmah4, R. Simon4, Yu.G. Sobolev14, S. Spataro8, B. Spruck8, H. Ströbele7, J. Stroth7,4, C. Sturm7, M. Sudol4, A. Tarantola7, K. Teilab7, P. Tlusty14, M. Traxler4, R. Trebacz3, H. Tsertos12, I. Veretenkin10, V. Wagner14, H. Wen8, M. Wisniowski3, T. Wojcik3, J. Wüstenfeld5, S. Yurevich4, Y. Zanevsky6, P. Zhou5, P. Zumbruch4 collaboration 1Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, 95125 Catania, Italy2 LIP-Laboratório de Instrumentação e Física Experimental de Partículas , 3004-516 Coimbra, Portugal3 Smoluchowski Institute of Physics, Jagiellonian University of Cracow, 30-059 Kraków, Poland4 Gesellschaft für Schwerionenforschung mbH, 64291 Darmstadt, Germany5 Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, 01314 Dresden, Germany6 Joint Institute of Nuclear Research, 141980 Dubna, Russia7 Institut für Kernphysik, Johann Wolfgang Goethe-Universität, 60438 Frankfurt, Germany8 II.Physikalisches Institut, Justus Liebig Universität Giessen, 35392 Giessen, Germany9Istituto Nazionale di Fisica Nucleare, Sezione di Milano, 20133 Milano, Italy10 Institute for Nuclear Research, Russian Academy of Science, 117312 Moscow, Russia11 Physik Department E12, Technische Universität München, 85748 München, Germany12 Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus13 Institut de Physique Nucléaire (UMR 8608), CNRS/IN2P3 - Université Paris Sud, F-91406 Orsay Cedex, France14 Nuclear Physics Institute, Academy of Sciences of Czech Republic, 25068 Rez, Czech Republic15 Departamento de Física de Partículas, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain16 Instituto de Física Corpuscular, Universidad de Valencia-CSIC, 46971 Valencia, Spain GSI

  27. Bonus Slides Joachim Stroth

  28. W.K. Wilson (DLS coll.), Acta Phys. Pol. 29 (98) 3291 Joachim Stroth

  29. Joachim Stroth

  30. Joachim Stroth

  31. E. Bratkovskaya et al. Nucl. Phys. A Joachim Stroth

  32. Needless to show preliminary Joachim Stroth

  33. Comparison to L. Kaptari, B. Kämpfer calculations Black points – data Red poins – (data – h) [Phys. Rev. C 58, 2667 - 2670 (1998), H. Calén et al., “Measurement of the quasifree pn→pnh reaction”] Joachim Stroth

  34. Efficiency and acceptance corrected pp data,comparison to transport model calculation IQMD Δ→e+e-N seems to explain e+e- yield in p+p at 1.25 GeV Joachim Stroth

  35. Efficiency and acceptance corrected np data,comparison to transport model calculation (np cocktail) preliminary preliminary IQMD Data are not explained satisfactorily! Joachim Stroth

  36. Efficiency and acceptance corrected np data,comparison to transport model calculation (dp cocktail) preliminary preliminary IQMD dp cocktail do not explain data are not explained satisfactorily! Joachim Stroth

  37. Closer look to HSD An effect of the internal Fermi motion of the nucleons in the deuteron is hardly visible Joachim Stroth

  38. Joachim Stroth

More Related