A.Khanzdeev, October_2009, Split

MUCH related activity at PNPI

A.Khanzadeev, for PNPI team

● Detector R&D of MUCH central part● Software development● Layout studies● Physics analysis

GEM+MICROMEGAS tracking detector is considered as candidate for central region.

Pillars made by chemical etching from photo-resistant layer 4mm between pillars, diameter of each pillar - 300μm, height - 70μm

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).

A.Khanzdeev, October_2009, Split

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

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)

Some results of R&D which have been presented at last meeting to refresh your memory

A.Khanzdeev, October_2009, Split

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

A.Khanzdeev, October_2009, Split

Adding 10% of Ar makes mixture similar to Ar based mixtures from point of gas gain and spark probability

■ Try gas mixture with lager % of CF4 or Ar

Inefficiency

1.5%

0.6%

+10% Ar

+20% Ar

0.38%

+30% Ar

Inefficiency

~3.3%

~0.36%

~0.06%

+8% CF4

+18% CF4

+28% CF4

+25% CF4

A.Khanzdeev, October_2009, Split

Increasing % of CF4 in He/CF4/iC4H10 is more effective because of lager Z

■ Measuring the collection time for chosen working gas

A.Khanzdeev, October_2009, Split

Ion drift velocity (measured with 55Fe)Electron drift velocity (measured with 90Sr)

● 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)

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

■ Building two prototypes (MICROMEGAS+GEM and MICROMEGAS+TGEM) for beam test

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

Software development - 1Software 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)

Software development - 2Software development - 2• 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.

Qmax

Q

Qthr

Primary cluster

pads

thr

Layout studiesLayout studies• 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).

Y spacerY spacer

X spacerX spacer

Front side Back side

Overlap

Dead zone

Physics analysisPhysics analysis• Feasibility studies on hyperon reconstruction @ SIS100 updated (E. Kryshen) –

results are similar to previous analysis.

ΩΞ

• 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.