June 22, 2009 P. Colas - Analysis meeting 1 D. Attié, P. Colas, M. Dixit, Yun-Ha Shin (Carleton and Saclay) Analysis of Micromegas Large Prototype data 3rd analysis meeting - June 22, 2009

Outline June 22, 2009 P. Colas - Analysis meeting 2 Comparison between two resistive modules Resolution measurements Distortions Momentum resolution

Three panels were successively mounted and tested in the Large Prototype and 1T magnet: -standard anode -resistive anode (carbon loaded kapton) with a resistivity ~ 2.8 MΩ/□ -resistive ink (~1-2 MΩ/□) ready for next beam tests Bulk Micromegas panels tested at DESY June 22, Standard bulk Micromegas module Carbon loaded kapton Micromegas module P. Colas - Analysis meeting May-June 2009 November 2008

Beam test conditions at B=1T June 22, Bulk Micromegas detector: 1726 (24x72) pads of ~3x7 mm² AFTER-based electronics (72 channels/chip): –low-noise (700 e-) pre-amplifier-shaper –100 ns to 2 μs tunable peaking time –full wave sampling by SCA Beam data (5 GeV electrons) were taken at several z values by sliding the TPC in the magnet. Beam size was 4 mm rms. –frequency tunable from 1 to 100 MHz (most data at 25 MHz) –12 bit ADC (rms pedestals 4 to 6 channels) P. Colas - Analysis meeting

Determination of z range June 22, P. Colas - Analysis meeting cosmic run at 25 MHz of sampling frequency  time bin = 40 ns TPC length = cm in agreement with survey 190 time bins

Beam data June 22, P. Colas - Analysis meeting In addition to January data, new beam data at 1T were taken : 500 ns shaping, with and wo zero suppression, z=5,10,15,20,25,30,40,50 Frequency scan Electronic gain scan (change amplifier gain, compense with gas gain) Laser test, phi scan Excel file exists, most data converted to LCIO Standard conditions 230 V/cm Low diffusion conditions 140 V/cm Peaking time (ns) z (cm) * 287* * 304* Standard conditions (25 MHz) 230 V/cm Peaking time (ns) z (cm) 100 no Shaping500 + Shaping ZSNo ZSZS / / /

Pad signals: beam data sample June 22, RUN 284 B = 1T T2K gas Peaking time: 100 ns Frequency: 25 MHz P. Colas - Analysis meeting

Two-track separation June 22, P. Colas - Analysis meeting r φ z

Determination of the Pad Response Function June 22, Fraction of the row charge on a pad vs x pad – x track (normalized to central pad charge)  Clearly shows charge spreading over 2-3 pads (data with 500 ns shaping) Then fit x(cluster) using this shape with a χ² fit, and fit simultaneously all lines x pad – x track (mm)  Pad pitch  P. Colas - Analysis meeting x pad – x track (mm)

Residuals (z=25 cm) June 22, Residuals (x row -x track ) are gaussians row 1row 2row 3 row 4 row 5row 6 P. Colas - Analysis meeting

Residual bias (z=25 cm) June 22, Bias remaining after correction: mean of residual x row -x track = f(x track ) Variation of up to 50 μ m with a periodicity of about 3mm (pad width) row 0 row 3 row 8 P. Colas - Analysis meeting row 1 row 2row 4 row 5

Spatial resolution June 22, P. Colas - Analysis meeting Resolution at z=0: σ 0 = 54.8±1.6 μm with mm pads (w pad /55) Effective number of electrons: N eff = 31.8±1.4 consistent with expectations Preliminary

Field distortion measurement using laser June 22, P. Colas - Analysis meeting Beam position 5 cm two laser devices installed on the endplate to light up photosensitive pattern on the cathode (spots and line) deterioration of resolution at z > 40 cm : due to low field 0.9 to 0.7 T in the last 20 cm (significant increase of transverse diffusion) 30 cm50 cm B field map of the magnet Photoelectrons from the cathode pattern

Description of the resistive anodes DetectorDielectric layerResistive layerResistivity (MΩ/□) Resistive Kapton Epoxy-glass 75 μm C-loaded Kapton 25 μm ~4-8 Resistive Ink Epoxy-glass 75 μm Ink (3 layers) ~50 μm ~1-2 Resistive KaptonResistive Ink PCB Prepreg Resistive Kapton PCB Prepreg Glue 1-2 μm Glue 1-2 μm June 22, P. Colas - Analysis meeting Resistive Ink 14

Comparison at B=1T, z ~ 5 cm Resistive KaptonResistive Ink RUN 310 v drift = 230 cm/μs V mesh = 380 V Peaking time: 500 ns Frequency Sampling: 25 MHz RUN 549 V drift = 230 cm/μs V mesh = 360 V Peaking time: 500 ns Frequency Sampling: 25 MHz June 22, P. Colas - Analysis meeting 15

Pad Response Functions, z ~ 5 cm Resistive Kapton June 22, 2009 P. Colas - Analysis meeting Resistive Ink Γ = 7 mm δ = 10 mm Γ = 11 mm δ = 13 mm 16 x pad – x track (mm)  σ 0 = 68 μm  σ 0 = 130 μm ! 16

2.2 GeV Momentum June 22, P. Colas - Analysis meeting 17

Further tests for Micromegas In 2008/2009 with one detector module In 2010 with 7 detector modules. Reduce the electronic with possibility to bypass shaping Resitive technology choice 4 chips Wire bonded Front End-Mezzanine June 22, P. Colas - Analysis meeting 18

Conclusions Two Micromegas with resistive anode have been tested within the EUDET facility using 1T magnet to reduce the transverse diffusion C-loaded Katpon technology gives better result than resistive ink technology First analysis results confirm excellent resolution at small distance with the resistive C-loaded Kapton: 55 μ m for 3 mm pads The moving table is necessary to fix the inhomogeneous B field at high z Plans are to test several resistive layer manufacturing process and RC, then go to 7 modules with integrated electronics. Next step is making 2 new detectors, identical except the routing (we have 2 routings) both in CLP but a new, lower resistivity one. Should be close to ideal. June 22, P. Colas - Analysis meeting 19

Acknowledgments June 22, P. Colas - Analysis meeting Saclay, France: –D. A. –P. Colas –M. Riallot Carleton Univ., Canada: –M. Dixit –Y.-H. Shin –S. Turnbull –R. Woods DESY/EUDET