H igh A cceptance D i- E lectron S pectrometer

1. High Acceptance Di-Electron Spectrometer The activity of JINR for HADES project is performed in frame of theme 03 -1 - 1020 - 96/2005 with a first priority. Leader from JINR: Yu. Zanevsky Institutes of Germany: GSI (Darmstadt), University (Frankfurt), Technical University (München), University (Giessen), Forschungzentrum (Rossendorf) Laboratories of JINR: VBLHE, BLTP _________________________________________________________ http:// www-hades.gsi.de http:// lhedl.jinr.ru 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

2. High Acceptance Di-Electron Spectrometer HADES detector is designed to provide an excellent mass-resolution (~1 %) and very large acceptance for comprehensive studies of the behavior of ,  and  - mesons in the nuclear medium. TOFINO Magnet SC toroid ( 6 coils) • 2p in f18o < J < 85o Lepton Identification • RICH C4F10 + gas Phot. Det. CsI - cathode • META TOF scintillator wall + • Pre-Shower detector Tracking p – measurement vertex reconstruction • MDCDrift chambers cell size » 0.5 .. 3 cm dx ~ 100 mm (s) 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

3. HADES collaboration • Bratislava (SAS, PI) • Catania (INFN - LNS) • Clermont-Ferrand (Univ.) • Cracow (Univ.) • Darmstadt (GSI) • Dresden (FZR) • Dubna (JINR) • Frankfurt (Univ.) • Giessen (Univ.) • Milano (INFN, Univ.) • Moscow (ITEP, INR, MEPhI) • Munich (Tech. Univ.) • Nicosia (Univ.) • Orsay (IPN) • Rez (CAS, NPI) • Sant. de Compostela (Univ.) • Valencia (Univ.) 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

4. HighAcceptanceDi-ElectronSpectrometer 3D sketch of the HADES spectrometer, split along the longitudinal direction for clarity. In operating conditions all the shown elements fit into each other making the whole structure much more compact. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

5. Main items of JINR activity for HADES •Full-size Prototype ofmultilayer Drift Chamber has been developed and tested • Front End Electronics for Drift Chambers has been developed and tested. •Six low mass multilayer Drift Chambers (plane 2) were constructed, testedandintegrated into the HADES spectrometer. • Track reconstruction software has been developed and successfullyapplied for data analysis ( ‘ Dubna Tracking Software ’ ). • Participation in physical program and data analysis. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

6. Full-size Drift Chambers Prototype Assembling of Prototype at JINR Testing of Prototype on the beam at GSI • The results of the test were very successful: • - High spatial resolution (~ 70 μm) and high efficiency • with gas mixture He + Isobutan. • - Long term stable operation. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

7. Front End Electronics for HADES Drift Chambers Very important parts - flat cables with 16-channels Ampl/Discr Cards The last test of Front End Electronics before installation into Magnet Front End Electronics for HADES Drift Chambers has been developed and tested by JINR team. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

8. Drift Chambers - assembling and installation 6 multilayer Drift Chambers (plane 2) were constructed and tested in Dubna. After the assembling and testing in HADES cave the Drift Chambers were installed into Magnet and the Commissioning has been started. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

9. Track reconstruction software for HADES 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

10. Spatial ResolutionofHADES Drift Chambers C. Muentz, Report on Vienna Instrum. Conference, Febr. 2004 Published in Nucl. Instr. Meth.535 (2004),242–246 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

11. Momenta Resolution for 2, 3 and 4 Drift Chambers planes Resolution [%] p 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

12. From the Report of P. Salabura on PAC / GSI, September 2004 DETECTOR STATUS 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

13. Data Analysis and Experimental Program • During the production beamtimes of 2002 - 2004 were collected : • ~ 210 mio events C+C@ 2,2 AGev (2002) • ~ 500 mio events C+C@ 1,0 AGev (2004) • ~ 400 mio events p+p@ 1-2,5 Gev (2004) • Data analysis is in progress • Development of further physical program on SIS and • on future accelerator facility FAIR (A + A at 2-8 AGev). Nearest Physical Program 1. Dielectrons from pp/pd 2. On threshold η production in d+p 3. ω production in pp collisions 4. Dielectrons from Ca+Ca The results will be discussed on the next HADES Collaboration Meeting in Dubna, 7-12 June 2005. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

14. Data Analysis:Dielectrons, Vector Mesons Preliminary M [GeV/c²] Experimental data: C+C@2.2AGeVNov’2002 Spectrum of effective mass of e+ e¯ pair (red color). There is a good agreement with simulation (outer Drift Chambers were not installed, ΔP/P is ~ 8%). Simulation: Ca+Ca @ 2.2 AGev ΔP/P is improved up to ~ 2 % (with outer Drift Chambers were installed in HADES Spectrometer). 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

15. Main items of JINR team activity in 2002-2004 • 1. Simulation of pp interactions at various energies (including electromagnetic decay of hadrons). • 2. Track reconstruction and momentum determination software. • 3. On-line and off-line vertex reconstruction. • 4. “Event Display” program (a first version), monitoring of drift chambers data quality. • 5. Participation in the commissioning, HADES experimental program and data analysis: • - C+C (1.5-2.0 AGeV) • - p+p (1.5-2.2 GeV) • Participation in development of the ALIGNMENT software. • The work is supported by INTAS grant No. 03-51-3208 for HADES • and grants of JINR/BMBF Committee 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

16. Event display The software has been developed by P. Biriukov from LIT (JINR) 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

17. Online vertex reconstruction(Nov02 data) 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005

18. CONCLUSIONS • The HADES spectrometer offers a unique possibility for systematic studies of the light vector meson mass distributions inside nuclear matter by means of di-electron spectroscopy. • Recent results from commissioning runs confirmed the expected superior on-line and off-line electron identification capabilities. In particular, a high-statistics run with LVL2 trigger provided first pair data from C+C reactions at 2 AGeV. • High resolution di-electron spectroscopy becomes now also possible, after the completion of the outer MDC tracking system. • The full experimental program is planned for several years. First experiments aiming at the exclusive meson reconstruction in proton-proton reactions have been started in 2004. High resolution studies of the vector meson production in pion induced reactions and light nucleus-nucleus system are planned in next 2-3 years. • The HADES experimental program for FAIR (2-8 AGev) is under development. • The JINR activity for HADES project was very appreciated in the recommendations of JINR/BMBF Committee and previous Workshops on the Scientific Cooperation between German Research Centers and JINR. 5th Workshop on the Scientific Cooperation between German Research Centers and JINR, 17-19 January, 2005