Tracking in a TPC - University of Victoriakarlen/talks/tpc/karlen-tpc-fnal07.pdf · Oct 24, 2007 D....
Transcript of Tracking in a TPC - University of Victoriakarlen/talks/tpc/karlen-tpc-fnal07.pdf · Oct 24, 2007 D....
Tracking in a TPCTracking in a TPCD. Karlen / U. Victoria & TRIUMF
for the LCTPC collaboration
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TPC trackingTPC trackingTime Projection Chambers have performed well as the main tracker in a wide range of physics experiments & environments• eg. underground, LEP, heavy ion collisions
RDR IV-74
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TPC trackingTPC trackingIs a TPC tracker suitable for the environment and physics at the ILC?• ie. will operate well and not compromise the
physics potential of the ILC?
A growing worldwide community has been active for many years to answer this question• we must have a definitive answer before the
ILC lab is ready to approve detector construction
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Key physics issuesKey physics issuesMomentum resolution• recoil mass (HZ0)• μμγ lumi spectrum
Pattern recognition
Low mass• preserve good jet energy resolution
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Key environmental issuesKey environmental issuesBeam structure
• TPC integration time: O(100) BX• low duty factor – pulsed electronics
Machine backgrounds• will additional occupancy break pattern
recognition?• will TPC suffer HV incidents?
Magnetic field non-uniformities• can corrections recover momentum resolution?
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TPC R&D programTPC R&D programThe ILC TPC R&D program began by tackling the momentum resolution question early this decade• It was quickly realized
that to achieve theresolution goals, thegas amplification systemmust be miniaturized
• Natural application formicro pattern gas detectors
GEM
Micromegas
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Momentum resolutionMomentum resolutionSpatial resolution• several small prototypes
constructed by groupsaround the world
15-60 cm drift5-15 mm2 padsB=0-5 T
• spatial resolutiontargets achieved forlarge B (100 μm orbetter per pad row)
• reported at previousmeetings
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New developmentsNew developmentsVery fine segmentation is possible with silicon sensors readout (medipix / timepix)• 55 μm × 55 μm pixels detect signals from
individual primary ionization electrons• possible improvement in dE/dx resolution
Integrated amplification stage, with spark protection:• with 20 μm
resistive layer,silicon survivesbreakdowns now
J. Timmermans, Nikkef
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TimepixTimepix eventseventsLike a miniature bubble chamber
cosmics (time mode) alphas (amplitude mode)
14 mm
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PixilizedPixilized readoutreadoutFor the GEM+pixel option, the diffusion after gain spreads the charge over many pixels. Larger pixels would allow lower gain in the amplification stage• developments
underway toincrease pixelsize – usefulfor GEM+pixeloption
before after
Post processing on a single chip
55x5555x55µµmm22 110x110110x110µµmm22
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…… beyond spatial resolutionbeyond spatial resolutionMost of the other issues need larger scale hardware & software efforts to address• LCTPC group developing into a formal
collaboration
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LCTPC goalsLCTPC goalsBuild a large prototype TPC for test beams and cosmic ray operation in a magnet• tiled endplate• interchangeable modules using different
amplification technologies• high density electronics developments• EUDET program provides much of the
necessary infrastructure
Build software suite suitable for simulation and reconstruction:• for use with prototype data (test beam and
cosmics) and full size TPC with ILC events
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Field cage designField cage design
R. Diener
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Field cageField cageTight tolerances
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Populated endplatePopulated endplate
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Readout designsReadout designs
GEM module (no side frames)A. Ishikawa
Bulk micromegasP. Colas
PixelreadoutM. Killenberg
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GatingGatingGating can reduce thenumber ions produced in the amplification stage.
Wire gating GEM gating
Gate Open
Gate Closed
A. Ishikawa
~50cm
μ
50mm/μsec
• gating can bedone with wiresor a GEMoperated atunit gain
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Power pulsingPower pulsingPower supplies designed for average power rather than peak powerDistributed charge storage capacitors close to the switchable loads supply the peak current. Allow ~ 1 volt drop during power on cycleLocal « Low dropout » voltage regulators keep voltage stable on the electronics
Properly controlled constant current sources recharge the capacitors between cycles
J.P. Martin (U. Montreal)
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Software developmentSoftware development
M. Killenberg U. Bonn
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ScorecardScorecardSpatial resolution – establishedPattern recognition – to start again• full pad readout simulation / reconstruction
Low mass – underway• field cage designs / electronics considerations
Beam structure – not demonstrated• tests at FNAL foreseen
Beam backgrounds – not demonstratedMagnetic field non-uniformities – starting• software development, large prototype tests
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SummarySummaryA worldwide team of people are working together towards the common goal of developing a TPC design that will satisfy the needs of the ILC physics programThe more challenging issues requiring large hardware and software investments are just getting underwayPlenty of room for new collaborators and new ideas!