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

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF2 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...

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF3 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

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF4 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

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF5 Cosmic ray tracking  The traditional approach:  examine data from each row separately: define a point along the track

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF6 Cosmic ray tracking  The traditional approach:  examine data from each row separately: define a point along the track  find best track that goes through points

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF7 Cosmic ray tracking  The traditional approach:  examine data from each row separately: define a point along the track  find best track that goes through points  measure resolution by the scatter of the dots from the track

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF8 Cosmic ray tracking  Problem with the traditional approach:  information in one row is not sufficient to define a point along the track:  charge sharing depends on  x coordinate  azimuthal angle  width of charge cloud  dependence is non-linear  linear centroid finding degrades resolution

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF9 Cosmic ray tracking  Our whole track approach:  combine information from all rows to determine the track parameters:  x coordinate  azimuthal angle  width of charge cloud  the concept of a point on the track is non-existent  x resolution for a single row is measured by performing two track fits

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF10 Cosmic ray tracking  The sharing of charge by neighbouring pads is a simple enough concept to develop a first principles model for maximum likelihood  Benefits of the whole track approach:  no empirical parameters  less calibration  reasonable estimates for error matrix  better resolution

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF11 News from the Eastern Front  Finalizing analysis of data from TPC-1b  F analysis code developed

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF12 Transverse resolution  100  m resolution achieved with 2 mm pads… further improvements expected

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF13 Resistive anode studies  To spread signals over larger area, a resistive film can be used:  Especially important for Micromegas…

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF14 Resistive anode studies  Early results look promising

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF15 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

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF16 Victoria group  Graduate student:  Gabe Rosenbaum  RA (part-time):  Paul Poffenberger  Summer students:  Camille Belanger-Champagne  Brie Hoffman  Technical support: (many)  D.K.

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF17 TPC2 commissioned  Constructed at Carleton University, operated at the University of Victoria with cosmic telescope

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF18 Data acquisition  Cross compiler built (Paul)  can compile applications for STAR electronics on Linux, and load onto VxWorks platform  see 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

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF19 Tracking with 6 STAR FEE cards

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF20 Tracking distortions found  Residual from track depends on track location: x coordinate (mm) mean residual for centre row (mm)

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF21 TPC modification  End of drift volume had a wire mesh to terminate cylindrical volume just in front of square GEMs: source of field distortions? wire mesh drift volume

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF22 TPC modification  New endpiece constructed:  70  m wire strung with 2.5 mm spacing

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF23 Tracking distortions fixed  With new end piece, problem is solved x coordinate (mm) mean residual for centre row (mm)

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF24 Analysis code  Track fitting now with curvature data taken with no mesh: large field distortions!

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF25 Setup at TRIUMF

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF26 Example events at ~25 cm drift 0 Tesla0.45 Tesla0.9 Tesla  = 2.3 mm  = 1.2 mm  = 0.8 mm Gas: P10

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF27 Diffusion measurements  Transverse diffusion significantly reduced at high B fields B = 0 B = 0.45 T B = 0.9 T 3cm 30 cm B (T) D (  m/  cm) (Data) D (  m/  cm) (MC)

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF28 Track resolution  Fit track to all but one row  fix  0, 1/ r, and , fit to one row alone  compare x 0 from the two fits  fit to Gaussian 3cm 30 cm TDR spec. goal B = 0 B = 0.45 T B = 0.9 T

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF29 Resolution dependencies  No large dependencies on threshold or gain  Track angle effect visible ~ 2 primary ~ 1 primary ~ 5000 ~ <  < <  < 0.1

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF30 Comparison with MC simulation  Good agreement  MC truth info confirms that procedure to measure resolution is sensible

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF31 Induction signals visible  Pads next to those collecting electrons see induced pulses (also seen in our x-ray test cell)

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF32 Magnetic field distortions  Field not completely uniform within drift volume:  cause ionization tracks to rotate in azimuth

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF33 Magnetic field distortions  To check, use cosmic telescope to define a standard beam of cosmics  mean  angle changes in the direction expected

2003 ALCPG Cornell Meeting: 13/7/03TPC R&D in Canada / D. Karlen / UVic & TRIUMF34 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!