TPC R&D in Canada

1. TPC R&D in Canada Dean Karlen / University of Victoria & TRIUMF Canadian LC-TPC Group: Carleton University: Robert Carnegie, Madhu Dixit, Hans Mes, Kirsten Sachs University of Montreal: Jean-Pierre Martin University of Victoria: D.K., Paul Poffenberger, Gabe Rosenbaum

2. Outline • Focus of the Canadian LC-TPC R&D program • Updates: • On the eastern front: TPC1 • finalizing analysis of P10 and ArCO2 cosmic data from 2002 • investigation of resistive foil for induction signals • On the western front: TPC2 • first results from cosmic data in magnetic field (June 2003) • comparison with Monte Carlo simulation • Plans... TPC R&D in Canada / D. Karlen / UVic & TRIUMF

3. Focus of Canadian TPC R&D • Investigate the design of the end plate for the TPC to achieve its objectives: • micropattern gas avalanche detector • modest size pads: ~2 mm  ~6 mm pads • ~100 micron resolution per pad row in the transverse direction • good two particle separation power TPC R&D in Canada / D. Karlen / UVic & TRIUMF

4. Endplate design • Significant effort to study the performance of GEM devices with rectangular readout pads • cosmics used to measure resolution properties TPC 1A Fall 2001 TPC 1B Summer 2002 TPC 2 Summer 2003 TPC R&D in Canada / D. Karlen / UVic & TRIUMF

5. Cosmic ray tracking • The traditional approach: • examine data from eachrow separately: define a point along the track TPC R&D in Canada / D. Karlen / UVic & TRIUMF

6. Cosmic ray tracking • The traditional approach: • examine data from eachrow separately: define a point along the track • find best track that goesthrough points TPC R&D in Canada / D. Karlen / UVic & TRIUMF

7. Cosmic ray tracking • The traditional approach: • examine data from eachrow separately: define a point along the track • find best track that goesthrough points • measure resolution by thescatter of the dots from thetrack TPC R&D in Canada / D. Karlen / UVic & TRIUMF

8. Cosmic ray tracking • Problem with the traditional approach: • information in one rowis not sufficient to definea point along the track: • charge sharing depends on • x coordinate • azimuthal angle • width of charge cloud • dependence is non-linear • linear centroid findingdegrades resolution TPC R&D in Canada / D. Karlen / UVic & TRIUMF

9. Cosmic ray tracking • Our whole track approach: • combine information fromall rows to determine thetrack parameters: • x coordinate • azimuthal angle • width of charge cloud • the concept of a point on the track is non-existent • x resolution for a singlerow is measured byperforming two track fits TPC R&D in Canada / D. Karlen / UVic & TRIUMF

10. Cosmic ray tracking • The sharing of charge byneighbouring pads is a simple enough concept to develop a first principles model formaximum likelihood • Benefits of the whole trackapproach: • no empirical parameters • less calibration • reasonable estimates forerror matrix • better resolution TPC R&D in Canada / D. Karlen / UVic & TRIUMF

11. News from the Eastern Front • Finalizing analysis of data from TPC-1b • F analysis code developed TPC R&D in Canada / D. Karlen / UVic & TRIUMF

12. Transverse resolution • 100 mm resolutionachieved with 2 mmpads… furtherimprovements expected TPC R&D in Canada / D. Karlen / UVic & TRIUMF

13. Resistive anode studies • To spread signals over larger area, a resistive film can be used: • Especially importantfor Micromegas… TPC R&D in Canada / D. Karlen / UVic & TRIUMF

14. Resistive anode studies • Early results look promising TPC R&D in Canada / D. Karlen / UVic & TRIUMF

15. News from the Western Front • Progress since Arlington: • New TPC (TPC2) commissioned in Victoria • Cross compiler for STAR electronics developed to build more efficient DAQ system • Cosmic tracking indicated field distortions • TPC redesign fixed the distortions • TPC brought to TRIUMF for magnetic field tests • Track fitter extended for curved tracks • Begin using JAS3 for automated analysis • Analysis of the magnetic field runs • code is publicly available via anonymous CVS access TPC R&D in Canada / D. Karlen / UVic & TRIUMF

16. Victoria group • Graduate student: • Gabe Rosenbaum • RA (part-time): • Paul Poffenberger • Summer students: • Camille Belanger-Champagne • Brie Hoffman • Technical support: (many) • D.K. TPC R&D in Canada / D. Karlen / UVic & TRIUMF

17. TPC2 commissioned • Constructed at Carleton University, operated at the University of Victoria with cosmic telescope TPC R&D in Canada / D. Karlen / UVic & TRIUMF

18. Data acquisition • Cross compiler built (Paul) • can compile applications for STAR electronics on Linux, and load onto VxWorks platform • see www.linearcollider.ca for information • New data acquisition program (Paul/Gabe) • data runs written to single file • contains header information for run/event • only channels connected to FEE cards written • ~10% deadtime loss for cosmics TPC R&D in Canada / D. Karlen / UVic & TRIUMF

19. Tracking with 6 STAR FEE cards TPC R&D in Canada / D. Karlen / UVic & TRIUMF

20. Tracking distortions found • Residual from track depends on track location: mean residual for centre row (mm) x coordinate (mm) TPC R&D in Canada / D. Karlen / UVic & TRIUMF

21. TPC modification • End of drift volume had a wire mesh to terminate cylindrical volume just in front of square GEMs: source of field distortions? drift volume wire mesh TPC R&D in Canada / D. Karlen / UVic & TRIUMF

22. TPC modification • New endpiece constructed: • 70 mm wire strung with 2.5 mm spacing TPC R&D in Canada / D. Karlen / UVic & TRIUMF

23. Tracking distortions fixed • With new end piece, problem is solved mean residual for centre row (mm) x coordinate (mm) TPC R&D in Canada / D. Karlen / UVic & TRIUMF

24. Analysis code • Track fitting now with curvature data taken with no mesh: large field distortions! TPC R&D in Canada / D. Karlen / UVic & TRIUMF

25. Setup at TRIUMF TPC R&D in Canada / D. Karlen / UVic & TRIUMF

26. Example events at ~25 cm drift Gas: P10 0 Tesla 0.45 Tesla 0.9 Tesla s = 2.3 mm s = 1.2 mm s = 0.8 mm TPC R&D in Canada / D. Karlen / UVic & TRIUMF

27. Diffusion measurements • Transverse diffusion significantly reduced at high B fields B = 0 B = 0.45 T B = 0.9 T 3cm 30 cm TPC R&D in Canada / D. Karlen / UVic & TRIUMF

28. Track resolution • Fit track to all but one row • fix f0, 1/r, and s,fit to one rowalone • compare x0from the two fits • fit to Gaussian B = 0 B = 0.45 T TDR spec. goal B = 0.9 T 3cm 30 cm TPC R&D in Canada / D. Karlen / UVic & TRIUMF

29. Resolution dependencies • No large dependencies on threshold or gain • Track angle effect visible ~ 2 primary ~ 1 primary 0.05 < f < 0.1 ~ 5000 0 < f < 0.05 ~ 2500 TPC R&D in Canada / D. Karlen / UVic & TRIUMF

30. Comparison with MC simulation • Goodagreement • MC truth info confirms thatprocedure tomeasure resolutionis sensible TPC R&D in Canada / D. Karlen / UVic & TRIUMF

31. Induction signals visible • Pads next to those collecting electrons see induced pulses (also seen in our x-ray test cell) TPC R&D in Canada / D. Karlen / UVic & TRIUMF

32. Magnetic field distortions • Field not completely uniform within drift volume: • cause ionization tracks to rotate in azimuth TPC R&D in Canada / D. Karlen / UVic & TRIUMF

33. Magnetic field distortions • To check, use cosmic telescope to define a standard beamof cosmics • mean f anglechanges inthe directionexpected TPC R&D in Canada / D. Karlen / UVic & TRIUMF

34. Plans for TPC2 • With the successful TRIUMF magnet tests, we will take the TPC to DESY for tests in their superconducting magnet (up to 5 Tesla) • starts next week! TPC R&D in Canada / D. Karlen / UVic & TRIUMF