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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 1 The EUDET facility at DESY Hamburg See K.Dehmelt’s talk PCMAG: KEK superconducting magnet, 1.2 T • e- test beam @DESY (1GeV/c<p<6GeV/c) SiPM Cosmic Trigger Setup Saclay Moving frame DESY LP : part of a TPC endplate Cornell 20/10/2010 Wenxin.Wang_IWLC meeting 2010 2 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 20/10/2010 Read out by T2K electronics Wenxin.Wang_IWLC meeting 2010 3 5 Micromegas Modules for TPC Module 4&5 2 Resistive Kapton ~3 MΩ/□ Resistive Kapton Standard ~5 MΩ/□ Module 2 Resistive ink ~3 MΩ/□ 20/10/2010 Wenxin.Wang_IWLC meeting 2010 4 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 5 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 6 20/10/2010 Wenxin.Wang_IWLC meeting 2010 7 Data analysis results (B=0T) Vd (cm/μs) 9 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) 8 7 6 5 4 3 Simulations (Magboltz) 2 Measurements 1 0 0 100 200 300 400 Ed (V/cm) 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 8 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 9 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 10 Bias Bias after ±50µm ±50µm Bias before Bias due to non-uniformity can be easily corrected. (module 3 CLK, B=1T) 20/10/2010 Wenxin.Wang_IWLC meeting 2010 11 Residuals Position residuals xrow-xtrack 20/10/2010 Wenxin.Wang_IWLC meeting 2010 12 Uniformity MEAN RESIDUAL vs ROW number Z=5cm Z-independent distortions Distortions up to 50 microns for resistive ink (blue points) Z=35cm Rms 7 microns for CLK film (red points) Z=50cm 20/10/2010 Wenxin.Wang_IWLC meeting 2010 13 Uniformity Very Preliminary Average charge by row using 5GeV e- beam (B = 1T) 20/10/2010 Wenxin.Wang_IWLC meeting 2010 14 Uniformity (B = 0T) Very Preliminary Using cosmic-ray Average charge by row using cosmic-ray events 20/10/2010 Wenxin.Wang_IWLC meeting 2010 15 Data analysis results (B = 0T & 1T) Carbon-loaded kapton resistive foil 0 2 Cd2 z N eff B=0 T Cd = 315.1 µm/√cm (Magboltz) Module 4 20/10/2010 χ2 : 10.6 Ndf: 10 B=1 T Cd = 94.2 µm/√cm (Magboltz) Module 3 χ2 : Ndf: Wenxin.Wang_IWLC meeting 2010 29.1 11 16 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 17 Test in a high intensity beam Top Bottom 20/10/2010 Wenxin.Wang_IWLC meeting 2010 18 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 19 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 20 Thank you 20/10/2010 Wenxin.Wang_IWLC meeting 2010 21