PNPI, R&D MUCH related activity ● Segmentation ● Simulation of the neutral background influence ● R&D of the detectors for MUCH ● Preparation to the beam test A.Khanzadeev_GSI_April 2010

It was considered 10 variants of segmentation for 5 stations (each of them has 3 detecting layers): 1. Monolithic GEM design (no dead zones) 2. Module GEM design with modules of 25.6x25.6 cm 2 each 3. Module GEM design with modules of 51.2x51.2 cm 2 each Segmentation (E.Kryshen, M,Ryzhinski) A.Khanzadeev_GSI_April 2010

First station in case of monolithic design (left), case of modules 25.6X25.6 cm 2, and case of modules 51.2x51.2 cm 2 (right). Each variant of segmentation was tested for ω→µµ Pad size 2x2 mm 2 Pad size 4x4 mm 2 A.Khanzadeev_GSI_April 2010 Gap between absorbers 30 cm

Station 4 in case of: Modules of straw (left), blue lines – one dimension straw hits GEM modules 25.6x25.6 cm2 (right), points – 2D GEM hits A.Khanzadeev_GSI_April 2010

In the calculations: ■ compact MUCH ■ ω→µµ process ■ realistic hit producer ■ different thresholds for hit recognition ■ realistic detectors geometry (different variants of segmentation, realistic geometry of detecting layers, dead zones, and so on) Threshold for hit recognition A.Khanzadeev_GSI_April 2010 Monolith Modules 51.2x51.2 cm 2

FEE layout for the central area of Station 1 Sketch represents our current understanding Realistic pad layout by E.Kryshen and M.Ryzhinsky, pad size: 2*2 mm. Box represents FEE card of 512 channels + HUB and optical fiber interface. V.Nikulin A.Khanzadeev_GSI_April 2010

Power consumption: 5W (xyter) + ? ROC i.e. ~6W(?) per card or 3*430W in central area size of 50*50 cm. Thermal analysis is required Heat sink size: 30*40 mm; Type of the heat sink should be chosen (water/air or something else) Additional transverse size of the chamber should be taken into account A.Khanzadeev_GSI_April 2010

GEANT4 study of neutral background in CBM MUCH detector for Helium and Argon as two alternative working gas options. Victor Baublis, PNPI, March Layout of simulated setup Simulation was performed for simplified detector prototype consisting only from gas volume, FR-4/G10 construction walls and Ar/He gases 5 mm 2 mm A.Khanzadeev_GSI_April 2010

Origin vertex z coordinate distributions of the charged secondary particles which were produced inside the detector- prototype by the beam neutrons and photons. ■ For both options of working gas the contribution of the FR-4 walls in neutron and photon hit rate dominates ■ The hit rate of neutrons does not exceed 10% from the hit rate of photons ■ Total hit rate of neutral particles in the Argon is about 10% higher than in Helium Some results of the simulation A.Khanzadeev_GSI_April 2010

This year our main R&D activity – assembling and testing two prototypes. One of them – Double TGEM, another one – hybrid MICROMEGAS/GEM Anode structure 2048 pads with hidden contact holes Pad size 1.5x 3 mm 2 Working area 102x109 mm 2 Gap between pads 0.2 mm Preamp to take signals from mesh or TGEM A.Khanzadeev_GSI_April 2010 R&D of the tracking detector for MUCH

Double TGEM1/TGEM2 Ar/CO2/iC4H10 (90/8/2) GG vs. ΔVg1&ΔVg2 (ΔVg1=ΔVg2) (ΔVag=300V, ΔVg1g2=300V, ΔVcg=800V) GGx10 3 TGEM1, TGEM2 are identical: thickness – 0.53 mm step between holes – 1 mm hole diam.– 0.6 mm rim diam mm volts A.Khanzadeev_GSI_April 2010 For double TGEM1/TGEM2 we can reach Gas Gain up to 30∙10 3 and energy resolution fwhm ~30% without visible problems Gaps: Anode-G1 – 1.5mm G1-G2 – 1.5 mm Cathode-G2 – 4 mm The best energy resolution reached was 29% (fwhm)

Double TGEM1/TGEM2 A.Khanzadeev_GSI_April 2010 volts Gas gain X10 3 GG vs. ΔVg1&ΔVg2 (ΔVg1=ΔVg2) (ΔVag=300V, ΔVg1g2=300V, ΔVcg=800V – fixed) He/CF4/iC4H10 (75/23/2) During the test with 55 Fe double TGEM detector showed stable behaviour. Operation of the detector with He based gas mixture allows soft HV regime to get supposed for MUCH electronics value of GG=2∙10 4

Micromegas/GEM Energy resolution fwhm~36% 3.7 mm 2.6 mm 60 mcm Ar/CO2/iC4H10 (90/8/2) GEM – produced by CERN PCB has hidden contact holes GG vs. Vm&ΔVg (Vm=ΔVg) (ΔVmg=100V and 250V, ΔVcg=350V – fixed) Easy to get GG ~4∙10 5 We are taking signals from the mesh A.Khanzadeev_GSI_April 2010

He/CF4/iC4H10 (75/23/2) Micromegas/GEM GG vs. Vm (ΔVmg=50V, ΔVg=ΔVcg=0V – fixed) GG vs. ΔVg (Vm=400V, ΔVmg=260V, ΔVcg=400V – fixed) GG vs. Vm&ΔVg (Vm=ΔVg) (ΔVmg=260V, ΔVcg=400V – fixed) During the test with 55 Fe Micromegas/GEM detector showed stable behaviour. Operation of the detector with He based gas mixture allows very soft HV regime to get supposed for MUCH electronics value of GG=2∙10 4. It is enough to keep volts on Gem and volts on Micromegas A.Khanzadeev_GSI_April 2010 Easy to get GG ~4∙10 5

Plans for this year ■ Continue work on segmentation ■ Make beam test of the prepared prototypes A.Khanzadeev_GSI_April 2010