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D-R&D-2: TPC R&D

D-R&D-2: TPC R&D. R&D for TPC applications A TPC for the ILC. ILC – International Linear Collider. 3 designs out of 4 chose a TPC as a main tracker. The R&D is carried out worldwide by the LC-TPC collaboration. TPC – Time Projection Chamber. t. Ionizing particle.

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D-R&D-2: TPC R&D

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  1. D-R&D-2: TPC R&D R&D for TPC applications A TPC for the ILC P. Colas - TPC R&D

  2. ILC – International Linear Collider 3 designs out of 4 chose a TPC as a main tracker The R&D is carried out worldwide by the LC-TPC collaboration P. Colas - TPC R&D

  3. TPC – Time Projection Chamber t Ionizing particle Electrons separate from ions The electrons drift under the E field E B The magnetic field reduces electron diffusion y x x-y coordinates given by the pads z coordinate given by the time P. Colas - TPC R&D

  4. S1 S2 Micromegas and GEM Micromegas : a micromesh supported by 50-100 mm - high insulating pillars. Multiplication takes place between the anode and the mesh. One stage GEM: Two copper perforated foils separated by an insulator (50 mm) Multiplication takes place in the holes. Usually used in 2 or 3 stages, even 4 200 mm P. Colas - TPC R&D

  5. Outline • The team • Collaborative activities since 2005 • Achievements • Projects P. Colas - TPC R&D

  6. The team • JAPAN • KEK/IPNS • K. Fujii • M. Kobayashi • H. Kuroiwa • T. Matsuda • R. Yonamine • Saga • A. Aoza • (H. Fujishima) • T. Higashi • A. Ishikawa • A. Sugiyama • H. Tsuji • Kinki U. • Y. Kato • T. Yazu • K. Hiramatsu • Hiroshima U. • T. Takahashi • Tokyo TUAT • M. Bitou • (M. Habu) • (K. Nakamura) • O. Nitoh • H. Ohta • K. Sakai • Kogakuin • T. Watanabe • FRANCE • CEA/Dapnia Saclay • (D. Burke) • M. Chefdeville • P. Colas • A. Giganon • I. Giomataris • M. Riallot • F. Sénée • S. Turnbull • CNRS/IN2P3 Orsay • V. Lepeltier (LAL) • Ph. Rosier (IPN) • T. Zerguerras (IPN) P. Colas - TPC R&D

  7. Collaborative activities • (pre-)History • In Japan : CDC group, legacy of Tristan and LEP/SLC, back to the 1990s, worked on a Central Drift Chamber • In Europe and America: in the the early 2000s, started R&D on MPGD TPCs. In 2002, M. Ronan, M. Dixit and P.C visited KEK and advertised TPC. In 2003-2004, R. Settles (MPI Munich) initiated a collaboration to test the 3 technologies : wires, GEM and Micromegas. P. Colas - TPC R&D

  8. Collaborative activities • In 2004 in Paris, we (Orsay-Saclay) decided to join and to bring a Micromegas endplate, adapted to the MPI field cage • Use the PCMAG magnet(s) and the p2 4 GeV pion beam at KEK PS, the trigger setup, and the ALEPH electronics • From pictures and mail exchanges, we made a 384-pad endplate and installed it at KEK in June P. Colas - TPC R&D

  9. In June 2005, we installed commissioned and took beam data From France: Paul Colas Arnaud Giganon Vincent Lepeltier Thomas Zerguerras P. Colas - TPC R&D

  10. Collaborative activities As the beam was available only until december, we decided to organise another data taking to test a new technique to spread the charge: the resistive foil technique (M. Dixit et al., Carleton U.) A second endplate was built in Saclay, with a resistive coating on the anode, and both the MPI and Carleton TPCs were run simultaneously in the same beam, push-pulling in the magnet. P. Colas - TPC R&D

  11. Beam tests in October 2005 at KEK Carleton-Saclay TPC MP-TPC Micromegas Charge dispersion readout endplates • - Micromegas 10 x 10 cm2 • - Drift distance: 16 cm • - 126 pads, 2 x 6 mm2 each in 7 rows • ALEPH preamps + 200 MHz FADCs • Micromegas 10 x 10 cm2 • Drift distance: 25 cm • - 384 pads, 2.3 x 6.3 mm2 each in 16 rows • ALEPH preamps + 11 MHz AlephTime Projection Digitizers P. Colas - TPC R&D

  12. Spreading of charge due to foil can be seen across six pads P. Colas - TPC R&D

  13. France-Japan meeting(s) in Paris in September 2006, followed by a 3-day endplate meeting with a large Japanese attendance (K. Fujii, Y. Kato, H. Kuroiwa, T. Matsuda, A. Sugiyama) http://www-dapnia.cea.fr/Spp/Meetings/EndPlate/ For the first time, a french attendance at the japanese MPGD meeting in Saga, in January 2007 (D. Attié, P. Colas) Participation of K. Fujii in a TPC analysis “Jamboree” in Aix-la-Chapelle, March 2007 P. Colas - TPC R&D

  14. Gasbox for studying gas gain fluctuations from the resolution on the 55Fe 5.9 keV line Blueprints drawn in Saclay. Realisation at KEK. 2 of these gasboxes built in Saclay, for gas+pixel and aging studies Saclay KEK P. Colas - TPC R&D

  15. The CF4 “saga” • We tried to take data with Ar CF4 • The detector was very unstable, very different from what we had in Saclay, with afterpulses. • We suspected Japanese CF4 to be different from European CF4 • After a complicated exchange of bottles and careful gas analyses, the two gases were shown to be the same • The difference was traced to the presence of impurities in the gas system in Saclay, quenching UVs • An admixture of 2% isobutane was found to be enough to stop the UVs and stabilise the operation. • This gas Ar CF4 isobutane (fast, low diffusion) is likely to be used by T2K and is favored for the ILC. It is being tested in KEK. P. Colas - TPC R&D

  16. Analysis of theJune test beam April-May 2006 : data analysis with 2 independent methods / programs P. Colas - TPC R&D

  17. Drift velocity measurement Achievements Using a beam at 45 deg. Look at time distribution on one pad. Max time gives drift time over 26.08+-0.02 cm (add trig. delay) • Cross-check of gas purity and MC simulation 1 cm scint. cathode Vdrift (Ar+5%iso, E=220V/cm) = 4.181 +- 0.034 cm/ms In agreement with Magboltz : 4.173 +- 0.016 P. Colas - TPC R&D

  18. Measurement of the diffusion coefficient at B=0, 0.5 and 1T 2 methods: global likelihood fit of the track width to all pad charges (shown here), or width of the PRF (slope at large distance is unbiased) in m/√cm Good agreement between the two methods and good agreement with Magboltz. P. Colas - TPC R&D

  19. Achievements Understanding the basic limitations of the resolution • Triggered by discussions on the data, the role of the ionization statistics, gas gain fluctuations and finite pad width were studied in detail (K. Fujii, M. Kobayashi) • Asymptotically, s2=s02+(DT2/Neff) z • Why is Neff much smaller than Ntot ? P. Colas - TPC R&D

  20. Study of the resolution (theory) • At large drift distance, transverse diffusion dominates: resol ~ CD√z/√Neff • Neff different from Ntot because of • Ionisation fluctuations 1/<1/N> • Gain fluctuations: x <G2>/<G>2 • At small distance, hodoscope effect: not enough charge spreading by diffusion to encompass more than 1 pad Ex: for 60 e- total, Neff=21.2±2.7 P. Colas - TPC R&D

  21. Resolution measurement B=0 r.m.s. of the residuals (√swithswo) 2 methods for the track: global likelihood fit or c2 fit Note: bias at small z - the track is reconstructed close to the middle of the central pad (hollow points) P. Colas - TPC R&D

  22. Resolution measurement B=0.5 and 1T P. Colas - TPC R&D

  23. P. Colas - TPC R&D

  24. P. Colas - TPC R&D

  25. Taking the finite pad width into account, K. Fujii derived a fully analytic formula for the resolution P. Colas - TPC R&D

  26. Scaling 1/√12 (use dimensionless quantities scaled by the pad width w) The resolution dependance on z has two regimes: At large z the asymptotic behaviour follows the diffusion limit At low z the effect of finite pad size dominates. For typical values of Neff, the optimal resolution is about 10% of the pad size. 1/√(12.Neff) P. Colas - TPC R&D

  27. Achievements KEK test beam Micromegas with resistive foil With charge spreading, the resolution was measured to be 50 microns at low z (and at all z for large enough B field) P. Colas - TPC R&D

  28. Extrapolation to ILC-TPC Conclusion: even with 1mm pitch, Micromegas with standard pads would not quite fulfill the requirement of better than 130 micron point resolution. However with a resisitive foil and 2.3 mm pads, this goal is largerly attained (red curve). P. Colas - TPC R&D

  29. Achievements Broken record on the 55Fe line resolution (5.6%) KEK, january 2007 threshold200 eV! P. Colas - TPC R&D

  30. Work in progress and plans • Large Prototype : a world collaboration by LC-TPC, using the EUDET infrastructure • PCMAG Magnet lend by KEK, associate to the EUDET project. Installed in DESY in December 2006 • CDC group, Canadian group, Tsinghua are responsible for the GEM panels. Saclay, Orsay and Carleton are responsible for the Micromegas panels => as much as possible development in common • A. Sugiyama and PC are coordinating GEM and Micromegas panels • A test of operation of GEMs and Micromegas with neutrons is necessary and the France-Japan collaboration explores this possibility • In 2008-2009, we will take data together at DESY in the PCMAG magnet, do the analysis together, in the scope of choosing the technology. P. Colas - TPC R&D

  31. Large Prototype panels D. Peterson, Cornell Saga GEM prototype panel (3700 channels) f = 80cm P. Colas - TPC R&D

  32. Summary • We maintained a privileged french-japanese axis in the worldwide collaboration for a Linear Collider TPC • This was the backbone of the Micromegas TPC beam tests • This collaboration was very fruitful and lead to a detailed understanding of the fundamental limitations on the resolution of a Micropattern TPC. • In the near future, we should bring a major contribution to the Large Prototype design and construction. P. Colas - TPC R&D

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