1. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 1 European gaseous tracking hardware HistoryHistory GEM and MicromegasGEM and Micromegas Ongoing R&DsOngoing R&Ds Preliminary studiesPreliminary studies –drift velocities –aging –ion feedback, extraction –tests in magnetic fields - electronics for tests P. Colas, DAPNIA Saclay

2. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 2 PRC R&D-01/03: LC TPC R&D The PRC recommends the approval of the proposed R&D programme. It encourages the collaboration to perform in high magnetic fields tests of the different end-plate geometries (GEM, MICROMEGAS and standard wire chambers) and to use the performance of the ALEPH TPC as bench mark for a TESLA detector. It asks for a status report in one year. DRAFT – Recommendations of the 52 nd Meeting of the PRC DESY 25-26 th October 2001 HISTORY A DECADE OF TRACKING STUDIES 1992: First discussions on detectors in Garmisch- Partenkirschen (LC92). Silicon? Gas? 1996-1997: TESLA Conceptual Design Report. Large TPC, 1.5 Mchan. 2000: TESLA Technical Design Report. Micropattern (GEM, Micromegas) as a baseline 5/2001: Kick-off of the R&Ds 11/2001: DESY PRC for the TPC (includes north-American teams) 5/2003: interim report planned

3. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 3 Challenging requirements: High two-track separation in jets both in Z and in R  (O(8mm)) High background from photons and neutrons (600 n/BX) Excellent jet resolution (E-flow) Particle identification High granularity Low ion feedback or efficient gating Low H-content of the gas High granularity, small diffusion electrons ions chamber => Micropattern detectors Low material budget of the endplate (thin frame) Good dE/dx resolution

4. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 4 GEM and Micromegas VeryVery GEM: Two copper perforated foils separated by an insulator The multiplication takes place in the holes. Usually used in 3 stages, even 4 Micromegas : a micromesh sustained by 50-100  m - high insulating pillars. The multiplication takes place between the anode and the mesh One stage 200  m

5. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 5 GEM and Micromegas S1/S2 ~ E amplif / E drift S1 S2

6. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 6 GOALS OF THE STUDY Assess the new technologies Choose a gas Understand the electron transparency, extraction efficiency, ion feedback Check that micropattern detectors keep their good properties in a magnetic field Study dE/dx resolution Obtain optimal position resolution Get in touch with industry for detector manufacturing (thinner frames, grids) Or improve the wire chamber technology Orsay: Small-gap, Asymmetric wire chamber Munich  >20 -> potential transverse diffusion less than 200  m at 1m

7. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 7 Due to the high value of  and the low grid transparency, does it work in a magnetic field? -> TESTS

8. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 8 TPC studies in the Saclay magnet (june 2002, Feb 2003) 2Tesla, 53cm bore diameter Aachen : small GEM device for current measurements 2T magnet in Julich 5T magnet in DESY (Orsay-Saclay : 1cm and 15cm micromegas TPCs for current measurements 2T magnet in Saclay

9. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 9 DESY Hamburg Large prototype

10. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 10 CERN-Karlsruhe: designed to fit in the DESY Magnet Berkeley-Orsay-Saclay to fit in the Saclay magnet Both will make use of the STAR electronics

11. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 11 Detector 1024 pads Pad layout Field cage Readout Berkeley-Orsay-Saclay TPC Under construction

12. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 12 Ar CF 4 Drift properties: attachment is negligible below 400 V/cm and above 15 kV/cm (supported by our measurements)

13. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 13 Novosibirsk: Russian GEM manufacturing company in Nijni Novgorod (80  m holes at a 140  m pitch) Possibility of gating the 1 st GEM by pulsing the HV on it.

14. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 14

15. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 15 Orsay-Saclay: no change observed in the iron 55 peak position beween 0 and 2T

16. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 16 No deterioration of the ion feedback (rather a small improvement for GEMs) The ion feedback is well understood for micromegas

17. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 17 DESY-Hamburg

18. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 18 Aachen-DESY-Hamburg-Rostock Orsay-Saclay Tests have been performed in a magnetic field Cosmic setup under construction with Berkeley Collaboration began with Canada for resolution improvement studies Silicon pixels for a digital readout. See individual electrons to reconstruct cluster by cluster. First need a GEM or a Micromegas to multiply each electron by 10 4 Medipix chip under study in Nikhef (Harry Van der Graaf, Jan Timmermans) First results very soon? MAY BE THE FUTURE Amsterdam Nikhef

19. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 19 STAR READOUT ELECTRONICS TEST BENCH Front end cards Pulse generator Mother board Optical link VME processor

20. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 20 Work on the STAR Electronics (J. Kaminski, S.Kappler, M Ronan)

21. Amsterdam, March 31, 2003 P. Colas - European R&D for gaseous trackers 21 CONCLUSION The R&D is being carried out in several places at the same time. There are two 2T and one 5T magnets in operation in Julich, Saclay and DESY. Lots of cross-collaborations, even through Atlantic. Intense simulation effort. In parallel, tests of various aspects of the micropattern detectors. Micromegas and GEM TPCs are currently operating in magnetic fields. Ion feedback, aging, transparency, gain, drift velocities are being studied for several gases.