1. Evgeny Kryshen (PNPI) Mikhail Ryzhinskiy (SPbSPU) Vladimir Nikulin (PNPI) Detailed geometry of MUCH detector in cbmroot Outline Motivation Realistic module design Implementation in cbmroot New segmentation algorithm Occupancy study Visual display for MUCH Supported from INTAS project 05-103-7484

2. Currently used geometry Evgeny Kryshen CBM collaboration meeting, 27 February 2008 2 Stations are simulated as simple shapes – 3mm disks filled with argon gas Distances between layers and absorbers are not realistic (too small) No support structures, no module design Segmentation algorithm is not flexible Parameter files are huge, full of irrelevant numbers, hardly readable, not flexible Geometry and segmentation parameters are described in different files

3. Module design in ALICE Evgeny Kryshen CBM collaboration meeting, 27 February 2008 3

4. Schematic layout of GEM module Evgeny Kryshen CBM collaboration meeting, 27 February 2008 4 Support structure Pads Fasteners Spacer PCB Readout electronics Argon GEM foils

5. Implementation of module design Evgeny Kryshen CBM collaboration meeting, 27 February 2008 5 Front side Back side 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 Overlap

6. Support structures and modules Evgeny Kryshen CBM collaboration meeting, 27 February 2008 6 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 ρ C )  Implemented as composite shapes in cbmroot Y spacers Active volume X spacers Module:  Module size is mostly restricted by the GEM foil production technology (up to 60 x 60 cm with the new machine at CERN)  Active volume: 30 x 30 cm x 0.3 cm, 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

7. Detailed geometry: general view Evgeny Kryshen CBM collaboration meeting, 27 February 2008 7 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

8. Geometry input file: much_detailed.geo Evgeny Kryshen CBM collaboration meeting, 27 February 2008 8 # 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 38 76 114 162 215 Absorber thickness [cm] : 20 20 20 30 35 100 Absorber material : I I I I I I # Station specification Station Zcenter [cm] : 29 67 105 151 206 327.5 Number of layers : 2 2 2 2 2 3 Detector type : 1 1 1 1 1 1 Distance between layers [cm]: 7 7 7 7 7 7 Support thickness [cm] : 1.5 1.5 1.5 1.5 1.5 1.5 Sigma X minimum [cm] : 0.04 0.04 0.04 0.04 0.04 0.04 Sigma Y minimum [cm] : 0.04 0.04 0.04 0.04 0.04 0.04 Sigma X maximum [cm] : 0.32 0.32 0.32 0.32 0.32 0.32 Sigma Y maximum [cm] : 0.32 0.32 0.32 0.32 0.32 0.32 Maximum occupancy : 0.05 0.05 0.05 0.05 0.05 0.05 # GEM module specification (type 1) Active volume lx [cm] : 30 Active volume ly [cm] : 30 Active volume lz [cm] : 0.3 Spacer lx [cm] : 0.5 Spacer ly [cm] : 5 Overlap along y axis [cm] : 2

9. Class hierarchy Evgeny Kryshen CBM collaboration meeting, 27 February 2008 9 CbmMuchGeoScheme CbmMuchStation CbmMuchLayer CbmMuchModule CbmMuchLayerSide CbmMuchSector CbmMuchPad

10. Segmentation: algorithm Evgeny Kryshen CBM collaboration meeting, 27 February 2008 10 Hit density vs R Each sector have to satisfy two conditions:  Estimated pad resolution in X and Y must belong to the allowed range, which is specified for each station in the parameter file  Estimated occupancy must be smaller than maximum allowed one x y

11. Segmentation: results Evgeny Kryshen CBM collaboration meeting, 27 February 2008 11 1 station 3 station 4 station  Sector sizes at the first station are mostly determined by occupancy restrictions  Starting from the 3 rd station sector sizes are determined by the required resolution  The smallest pad size in the default setup is ~2.3 mm (resolution ~ 680 μm).

12. Occupancies Evgeny Kryshen CBM collaboration meeting, 27 February 2008 12  Occupancy plots are produced by normalizing fired pad radial distributions by all channels radial distributions  Maximum occupancy at the first MUCH station ~ 5%  Occupancy at each station reduces at the outer regions of the station  Occupancies reduce down to 0.01% at the last station  Somewhat higher occupancies are expected for GEM

13. Track statistics / central event 123456 Total 6911866515.95.161.853 Primary 1052682.41.541.251 Secondary 5861615713.53.620.601 Protons 11444152.90.510.030 Pions 17952152.60.390.029 Electrons 37276265.91.530.291 Muons 10753.62.521.498 Kaons 15730.90.220.005 Evgeny Kryshen CBM collaboration meeting, 27 February 2008 13 Track statistics after the first absorber is dominated by secondary electrons (electromagnetic shower)

14. 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 Evgeny Kryshen CBM collaboration meeting, 27 February 2008 14

15. Visual Event Display: Module View Evgeny Kryshen CBM collaboration meeting, 27 February 2008 15 Zoomed module view Fired pads are marked with blue gradient colors reflecting the accumulated charge Found hits are marked with black markers

16. Visual Event Display: Cluster View Evgeny Kryshen CBM collaboration meeting, 27 February 2008 16 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.

17. Future plans See the talk by Misha Ryzhinskiy Evgeny Kryshen CBM collaboration meeting, 27 February 2008 17