Recents Analysis Results From Micromegas TPC D. Attié, P. Colas, M. Dixit, M. Riallot, YunHa Shin, S. Turnbull, W. Wang and all the LC-TPC collaboration 20/10/2010 Wenxin.Wang_IWLC meeting 2010

The EUDET facility at DESY Hamburg See K.Dehmelt’s talk PCMAG: superconducting magnet, 1.2 T e- test beam @DESY (1GeV/c<p<6GeV/c) KEK SiPM Cosmic Trigger Setup Moving frame DESY Saclay LP : part of a TPC endplate Cornell 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Micromegas TPC From December 2008 to March 2010 we tested 5 panels. One module was installed in the centre of the Large Prototype each time Read out by T2K electronics 20/10/2010 Wenxin.Wang_IWLC meeting 2010

5 Micromegas Modules for TPC Resistive ink ~3 MΩ/□ Resistive Kapton ~5 MΩ/□ Standard 2 Resistive Kapton Module 4&5 Module 1 Module 3 Module 2 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Bulk technology (à la T2K) The mesh is held by the pillars on the whole surface. There is not need for frame. Very robust. A T2K ND280 TPC event (in operation since 1 year 9 m² of bulk Micromegas Resistive bulk : continuous RC circuit to spread the charge to improve resolution 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Test schedule December 2009: tested modules 4 and 5 without magnetic field. March 2010: tested modules 2 (ink) and 3 (kapton) with 1T magnetic field. June-July 2010: data taken in a high intensity hadron beam at CERN. 20/10/2010 Wenxin.Wang_IWLC meeting 2010

20/10/2010 Wenxin.Wang_IWLC meeting 2010

Data analysis results (B=0T) Drift Velocity in T2K gas compared to Magboltz simulations for - P=1035 hPa - T=19°C - 35 ppm H20 ( T2K gas: Ar:CF4:iso=95:3:2) Vdrift = 7.698 +- 0.040 cm/µs at E=230 V/cm (Magboltz : 7.583+-0.025(gas comp.)) The difference is 1.5+-0.6 % B=0 data : Drift velocity measurements 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Data analysis results PRF : Pad Response Function A measure of signal size as a function of track position relative to the centre of the pad   The PRF: is not Gaussian. can be characterized by its FWHM (z) & base Width (z), plus another shape parameter. 20/10/2010 Wenxin.Wang_IWLC meeting 2010

PRF(Pad Response Functions) fits, z ~ 5 cm Data analysis results Γ ~ 4 mm δ ~ 14 mm Γ ~ 2.6 mm δ ~ 10 mm B=1T data : comparison of resistive ink and Carbon-loaded Kapton PRF(Pad Response Functions) fits, z ~ 5 cm 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Bias Bias before Bias after ±50µm Bias due to non-uniformity can be easily corrected. (module 3 CLK, B=1T) 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Residuals Position residuals xrow-xtrack 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Uniformity MEAN RESIDUAL vs ROW number Z-independent distortions Distortions up to 50 microns for resistive ink (blue points) Rms 7 microns for CLK film (red points) Z=5cm Z=35cm Z=50cm 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Average charge by row using 5GeV e- beam (B = 1T) Uniformity Very Preliminary Average charge by row using 5GeV e- beam (B = 1T) 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Uniformity (B = 0T) Very Preliminary Using cosmic-ray Average charge by row using cosmic-ray events 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Data analysis results (B = 0T & 1T) Carbon-loaded kapton resistive foil B=0 T Cd = 315.1 µm/√cm (Magboltz) B=1 T Cd = 94.2 µm/√cm (Magboltz) Module 3 χ2 :     29.1 Ndf:        11 Module 4 χ2 :     10.6 Ndf:    10 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Neff measurement with Micromegas Averaging B=0T and B=1T data (excluding ink module): Neff = 38.0±0.2(stat) ±0.8 (Cd syst) σ0= 59 ± 3 µm Assuming Polya distribution, =3.2± 0.7. Consistent with M. Lupberger’s thesis. See Michael Lupberger’s talk in EUDET meeting in Hamburg Note that 1/<1/N> = 47.1 from Heed for 5 Gev electrons on 6.84 mm long pads. This demonstrates that gain fluctuations are not exponential (Neff would be 23) but smaller. 1/<1/N> = 34.9 for 5.4 mm pads (GEM case). 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Test in a high intensity beam 27 cm 40 cm 35cm B field Top 11 cm Bottom 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Test at CERN (July 2010) at 180 kHz (5 x 2 cm² beam) showed no charging up and stable operation Peaking time of 200 ns is enough to obtain the best resolution -> 300 ns suffice to distinguish 2 tracks on the same pad 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Conclusions A lot of experience has been gained in building and operating Micromegas TPC panels The uniformity of the detector is excellent, with no distortions nor edge effects, and very small dead areas The measured resolution meets LC needs : 60 microns at zero drift distance with 3 mm wide pads The effective number of electrons per row is measured to be 38 The detector peformed perfectly normally in high intensity beam Next step is to equip the whole endplate with full integration of the electronics flat behind the panels 20/10/2010 Wenxin.Wang_IWLC meeting 2010

Thank you 20/10/2010 Wenxin.Wang_IWLC meeting 2010