A.Khanzdeev, October_2009, Split

1. MUCH relatedactivity at PNPI A.Khanzadeev, for PNPI team ● Detector R&D of MUCH central part ● Software development ● Layout studies ● Physics analysis A.Khanzdeev, October_2009, Split

2. GEM+MICROMEGAStracking detector is considered as candidate for central region. GEM (10x10 cm2) of CERN production For MICROMEGAS it was used rolled mesh of Russian production – stainless steel (wire - 32 μm in diameter, cell - 64μm). Pillars made by chemical etching from photo-resistant layer 4mm between pillars, diameter of each pillar - 300μm, height - 70μm A.Khanzdeev, October_2009, Split

3. Plans for this year R&D ■ Try gas mixture with lager % of CF4 or Ar ■ Measuring the collection time for chosen working gas ■ Building two prototypes (MICROMEGAS+GEM and MICROMEGAS+TGEM) for beam test ■ Preparing electronics for beam test ■ Would be nice to start beam test at PNPI accelerator A.Khanzdeev, October_2009, Split

4. Some results of R&D which have been presented at last meeting to refresh your memory Gas supply system for preparation of 3-component gas mixtures allowed to study Ar/CO2/iC4H10, He/CO2/iC4H10, Ar/CF4/iC4H10, and He/CF4/iC4H10. We found that He/CF4/iC4H10 mixture has very attractive features in comparing, for example, to Ar/CO2 mixture : ■ Much lower spark probability ■ Lower full collection time ■ Almost twice less transversal an longitudinal diffusions ■ The same gas gain can be reached under lower HV regime (almost twice less energy of discharge) A.Khanzdeev, October_2009, Split

5. ■ Try gas mixture with lager % of CF4 or Ar Drawback– number of produced pairs in He based gas mixture is ~4 times less than in Ar →inefficiency Looks reasonable to try He plus Ar or lager % of CF4 Inefficiency +20% Ar 0.6% +10% Ar 1.5% +30% Ar 0.38% Adding 10% of Ar makes mixture similar to Ar based mixtures from point of gas gain and spark probability A.Khanzdeev, October_2009, Split

6. Increasing % of CF4 in He/CF4/iC4H10 is more effective because of lager Z +28% CF4 +8% CF4 Inefficiency ~3.3% ~0.06% +25% CF4 +18% CF4 ~0.36% A.Khanzdeev, October_2009, Split

7. ■ Measuring the collection time for chosen working gas Electron drift velocity (measured with 90Sr) Ion drift velocity (measured with 55Fe) ● He/CF4/iC4H10 (73/25/2) As result – for such gas mixture (He/CF4/iC4H10 (73/25/2)) we can get collection time of ions in the mesh-anode gap plus drift time of electrons passing drift gaps at the level of 100-130 ns(for electron drift path of 4 mm and mesh-anode gap of 70 μm) A.Khanzdeev, October_2009, Split

8. ■ Building two prototypes (MICROMEGAS+GEM and MICROMEGAS+TGEM) for beam test • Anode structure: • 2048 pads; • Pad size 1.5x 3 mm2; • Working area 102x109 mm2; • Gap between pads 0.2 mm; • Mask-pad overlap 0.05-0.075 mm; • Through hole diameter 0.5 mm; • Board thickness 1mm A.Khanzdeev, October_2009, Split

9. We have all elements checked and enough understanding to assemble two prototypes of hybrid detectors and make in nearest future their assembling and beam testing

10. Software development - 1 Update in the MuCh geometry handling (E. Kryshen) – automatic calculation of station and layer dimensions, switching of detailed design on the level of stations. Straw tube option added (E. Kryshen & A. Zinchenko) Visualizer of straw tube hits implemented (E. Kryshen)

11. Software development - 2 Q Qmax  thr Qthr Primary cluster pads Manual segmentation added – full control over pad dimensions (M. Ryzhinskiy) Advanced cluster deconvolution algorithms studied – no significant improvement compared to simple algorithm. (M. Ryzhinskiy) Semirealistic timing in digis and hits implemented, quality analysis improved.

12. Layout studies Front side Back side Overlap X spacer Y spacer Dead zone Acceptance and track reconstruction efficiency analysis (E. Kryshen) Studies of dead zone effects (E. Kryshen): reconstruction efficiency significantly reduces due to dead zones in x-direction (finite x-spacer width).

13. Physics analysis Ω Ξ • Feasibility of J/psi polarization studies (E. Kryshen) – polarization can be reconstructed in several pt bins. Statistical error ~ 5 - 10% for 4 month data taking period. Feasibility studies on hyperon reconstruction @ SIS100 updated (E. Kryshen) – results are similar to previous analysis.