MUCH detector layout studies

1. MUCH detector layout studies • Outline • MUCH detector • FRRC project plan • Implementation of realistic module design • Segmentation algorithm • Visual display for MUCH • Straws in MUCH Evgeny Kryshen (PNPI) Mikhail Ryzhinskiy (PNPI & SPbSPU)

2. MUCH detector • Purpose: measurements of • vector meson decays: • J/ψ →µ+µ- • φ→ µ+µ- • ω→ µ+µ- • Physics impact: in-medium modification of hadrons, chiral symmetry restoration, deconfinement at high baryonic densities. • The main design feature: sandwich stracture – active absorbers for the suppression of background hadrons and efficient tracking of signal muons FRRC seminar, 9 June 2009

3. Track statistics / central event FRRC seminar, 9 June 2009

4. FRRC Project plan • Research method based on Monte-Carlo simulation of detector response. • Framework: CBMROOT + UrQMD generator + Geant3. • Steps: • Development of flexible software tools aimed for realistic geometry simulations. • Implementation of passive materials and support structures. • Development of tracking algorithms tuned for dimuon reconstruction. • Development of visualization tools. • Optimization of absorbers: position, materials, thickness. • Optimization of detector segmentation. • Choice of detector type (GEM, micromegas, straws etc). • Main expected result: realistic detector concept which meets experimental challenges in the most optimal and cost-effective way. FRRC seminar, 9 June 2009

5. Old (simplified) design • Stations are simulated as simple shapes – 3 mm disks filled with argon gas • Distances between layers and absorbers are not realistic (too small) • No support structures, no module design • Parameter files are huge, full of irrelevant numbers, hardly readable, not flexible FRRC seminar, 9 June 2009

6. Module design in ALICE FRRC seminar, 9 June 2009

7. Schematic layout of GEM module Pads Readout electronics PCB Argon Spacer Support structure Fasteners GEM foils FRRC seminar, 9 June 2009

8. Implementation of module design Front side Back side Overlap • Layers: • Modules are arranged in rows on both sides of each layer • There is an overlap of active volumes to avoid dead zones in y direction FRRC seminar, 9 June 2009

9. Support structures and modules • Support structures: • Each support structure is composed of two parts to assure easy installation around the pipe • Estimated thickness ~ 1.5 cm • Material: carbon plastics (ρ = 0.1 ρC) • Implemented as composite shapes in cbmroot • Module: • Module size is mostly restricted by the GEM foil production technology • Active volume: 256 x 256 mm x 3 mm, argon • Spacers: 5 cm in y, 0.5 cm in x; material: noryl, implemented as composite shapes • Active volume implemented as TGeoBox for simple modules and as composite shapes for modules with a hole X spacers Active volume Y spacers FRRC seminar, 9 June 2009

10. Detailed geometry: general view Module design Simple design • Two layers at each station • Three layers at the last trigger station • Modules are automatically located on the surface of support structures • Cables, gas tubes, PCBs and front-end electronics are neglected at the moment FRRC seminar, 9 June 2009

11. Geometry input file: much_standard_straws.geo # General information MuchCave Zin position [cm] : 105 Acceptance tangent min : 0.1 Acceptance tangent max : 0.5 Number of absorbers : 6 Number of stations : 6 # Absorber specification Absorber Zin position [cm] : 0 40 80 120 170 225 Absorber thickness [cm] : 20 20 20 30 35 100 Absorber material : I I I I I I # Station specification Station Zceneter [cm] : 30 70 110 160 215 340 Number of layers : 2 2 2 3 3 3 Detector type : 1 1 1 2 2 2 Distance between layers [cm]: 10 10 10 7 7 7 Support thickness [cm] : 1.5 1.5 1.5 0.0 0.0 0.0 Use module design (0/1) : 1 1 1 0 0 0 # GEM module specification (type 1) Active volume lx [cm] : 25.6 Active volume ly [cm] : 25.6 Active volume lz [cm] : 0.3 Spacer lx [cm] : 0.5 Spacer ly [cm] : 5 Overlap along y axis [cm] : 2 # Straw module specification (type 2) Straw thickness [cm] : 0.4 FRRC seminar, 9 June 2009

12. Class hierarchy CbmMuchGeoScheme CbmMuchStation CbmMuchLayer CbmMuchLayerSide CbmMuchModule CbmMuchSector CbmMuchPad FRRC seminar, 9 June 2009

13. Automatic segmentation: algorithm y Hit density vs R x // Set minimum allowed resolution for each station Double_t sigmaXmin[] = {0.04, 0.04, 0.04, 0.04, 0.04, 0.04}; Double_t sigmaYmin[] = {0.04, 0.04, 0.04, 0.04, 0.04, 0.04}; seg->SetSigmaMin(sigmaXmin, sigmaYmin); // Set maximum allowed resolution for each station Double_t sigmaXmax[] = {0.32, 0.32, 0.32, 0.32, 0.32, 0.32}; Double_t sigmaYmax[] = {0.32, 0.32, 0.32, 0.32, 0.32, 0.32}; seg->SetSigmaMax(sigmaXmax, sigmaYmax); // Set maximum occupancy for each station Double_t occupancyMax[] = {0.05, 0.05, 0.05, 0.05, 0.05, 0.05}; seg->SetOccupancyMax(occupancyMax); FRRC seminar, 9 June 2009

14. Automatic segmentation: results Simple design Module design • Sector sizes at the first station are mostly determined by occupancy restrictions • Starting from the 3rd station sector sizes are determined by the required resolution • The smallest pad size in the default setup is ~2 mm (resolution ~ 600 μm). FRRC seminar, 9 June 2009

15. Visual Event Display: Layer view Layer view functionality: • Switch between stations and layers • Info on stations • Zoom • Show info on hits, points and sectors • Switch off sectors, modules, layer sides, hits and points • Select particles with required PDG code and mothers • Browse events • Clickable sectors producing zoomed module views FRRC seminar, 9 June 2009

16. Visual Event Display: Module View Zoomed module view Fired pads are marked with blue gradient colors reflecting the accumulated charge Found hits are marked with black markers FRRC seminar, 9 June 2009

17. Visual Event Display: Cluster View Cluster view can be opened by clicking on a cluster in a module frame. It is aimed to help in optimization of hit finding algorithms. FRRC seminar, 9 June 2009

18. Straw tubes in Much geometry 4 m;  4 mm robustness high detection efficiency 100% geom. acceptance 97%/m rate capability 4 MHz/cm2 spatial resolution 200 m radiation length 0.2 % X0 granularity > 10 cm2 occupancy > 10% FRRC seminar, 9 June 2009

19. Calendar plan FRRC seminar, 9 June 2009