Date post: | 19-Jan-2016 |
Category: |
Documents |
Upload: | aubrie-knight |
View: | 219 times |
Download: | 0 times |
Evgeny Kryshen (PNPI)
Mikhail Ryzhinskiy (SPbSPU)
Vladimir Nikulin (PNPI)
Detailed geometry of MUCH detector Detailed geometry of MUCH detector in cbmrootin 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
Currently used geometryCurrently 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
Module design in ALICEModule design in ALICE
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
3
Schematic layout of GEM moduleSchematic layout of GEM module
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
4
Support structure
PadsPads
FastenersFasteners
SpacerSpacer
PCBPCB Readout electronicsReadout electronics
ArgonArgon
GEM foilsGEM foils
Implementation of module designImplementation 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
Support structures and modulesSupport 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 ρC)
Implemented as composite shapes in cbmroot
Y spacersY spacers
Active volumeActive volume
X spacersX 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
Detailed geometry: general viewDetailed 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
Geometry input file: much_detailed.geoGeometry input file: much_detailed.geo
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
8
# General informationMuchCave Zin position [cm] : 105Acceptance tangent min : 0.1Acceptance tangent max : 0.5Number of absorbers : 6Number of stations : 6
# Absorber specificationAbsorber Zin position [cm] : 0 38 76 114 162 215Absorber thickness [cm] : 20 20 20 30 35 100Absorber material : I I I I I I
# Station specificationStation Zcenter [cm] : 29 67 105 151 206 327.5Number of layers : 2 2 2 2 2 3Detector type : 1 1 1 1 1 1Distance between layers [cm]: 7 7 7 7 7 7Support thickness [cm] : 1.5 1.5 1.5 1.5 1.5 1.5Sigma X minimum [cm] : 0.04 0.04 0.04 0.04 0.04 0.04Sigma Y minimum [cm] : 0.04 0.04 0.04 0.04 0.04 0.04Sigma X maximum [cm] : 0.32 0.32 0.32 0.32 0.32 0.32Sigma Y maximum [cm] : 0.32 0.32 0.32 0.32 0.32 0.32Maximum occupancy : 0.05 0.05 0.05 0.05 0.05 0.05
# GEM module specification (type 1)Active volume lx [cm] : 30Active volume ly [cm] : 30Active volume lz [cm] : 0.3Spacer lx [cm] : 0.5Spacer ly [cm] : 5Overlap along y axis [cm] : 2
Class hierarchyClass hierarchy
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
9
CbmMuchGeoSchemeCbmMuchGeoScheme
CbmMuchStationCbmMuchStation
CbmMuchLayerCbmMuchLayer
CbmMuchModuleCbmMuchModule
CbmMuchLayerSideCbmMuchLayerSide
CbmMuchSectorCbmMuchSector
CbmMuchPadCbmMuchPad
Segmentation: algorithmSegmentation: 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
Segmentation: resultsSegmentation: results
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
11
1 station1 station 3 station3 station 4 station4 station
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 ~2.3 mm (resolution ~ 680 μm).
OccupanciesOccupancies
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
Track statistics / central eventTrack statistics / central event1 2 3 4 5 6
Total 691 186 65 15.9 5.16 1.853Primary 105 26 8 2.4 1.54 1.251Secondary 586 161 57 13.5 3.62 0.601Protons 114 44 15 2.9 0.51 0.030Pions 179 52 15 2.6 0.39 0.029Electrons 372 76 26 5.9 1.53 0.291Muons 10 7 5 3.6 2.52 1.498Kaons 15 7 3 0.9 0.22 0.005
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
13
Track statistics after the first absorber is dominated by secondary electrons (electromagnetic shower)
Visual Event Display: Layer viewVisual Event Display: Layer viewLayer 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
Visual Event Display: Module ViewVisual Event Display: Module View
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
15
Zoomed module viewZoomed module view
Fired pads are marked with blue gradient colors reflecting the accumulated chargeFound hits are marked with black markers
Visual Event Display: Cluster ViewVisual 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.
Future plansFuture plans
See the talk by Misha Ryzhinskiy
Evgeny Kryshen CBM collaboration meeting, 27 February 2008
17