ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 1 New geometry framework in MUON I.Hrivnacova IPN, Orsay ALICE Offline week, CERN 21 February 2005

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 2 Motivation Parametrisation of geometry – Extraction of the positions of selected pieces in a detector geometry - “detection elements” – Make possible to use them as input parameters and so to take into account the alignment Presentation at the last Offline week in September 2004 – Concentrated on the applied method This presentation – Will give a more detailed description of the introduced framework classes and their implementation for MUON – Will cover the development since that time

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 3 Logical Geometry Structure We have defined logical geometry units that represent sets of volumes in the geometry Three level structure: – Module - the biggest unit in a detector – Envelope - non-virtual and virtual – Envelope constituent – constituent of a virtual envelope Each unit represents a frame with respect to which its components are placed

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 4 Detection Element In a logical geometry hierarchy it corresponds to an envelope Detection element != a single volume in a MC geometry In real detector: Quadrant, slat, trigger chamber  Has an ID unique in the whole detector  Provides transformation between the global and its local frames  Object of alignment

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 5 Structural Objects Classes The elements defined before are represented in the framework via correspondent classes: –Alice coding convention + need to make this group of classes retrievable among ~ 90 other MUON classes has resulted in long class names: AliMUON*Geometry*XYZ –To make presentation clear, AliMUONGeometry prefix will be skipped... –The V prefix stands for abstract classes – Module, Envelope, EnvelopeConstituent, DetElement Structural objects – EnvelopeStore, GeometryStore, VDEIndexing Utility objects  Transformation representation: – TGeoMatrix class from Root

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 6 Structural objects Classes (2)

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 7 Structural objects Classes (3)

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 8 Building Geometry User CreateGeometry function now have to define also the logical geometry elements The framework builder classes help to simplify this: – User implements his detector construction class as a geometry builder derived from VBuilder associated with one or more Module object – The VBuilder base class provides utility functions for definition of Envelopes, EnvelopesConstituents and DetElements – Concrete examples of a user code were shown in the presentation at the previous offline meeting The main Builder than takes care of geometry construction via all user defined registered builders

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 9 Behavioral Objects Classes

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 10 Procedure of Building Geometry 1.Definition of the logical structures (modules, envelopes, envelope constituents) and all volumes trees placed inside them By UserBuilder : VBuilder objects 2.Placing the envelopes and their constituents with a composed transformation Automatic procedure – using the data stored in modules and envelopes, by main Builder object 3.Definition of detection elements and storing their global transformations By main Builder object

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 11 Geometry Parametrisation I/O Transformations defined in the logical volume structure can be exported to/imported from files Option whether these data will be taken from the files or from geometry definition in building geometry Defined in main Builder: SetAlign(), GetAlign() functions One file per user builder Includes data for several geometry modules Reading/writing files implemented in VBuilder ASCII files – temporary solution until such a functionality is provided via AliRoot framework

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 12 Geometry Parametrisation I/0 trasform_st1V2.dat Data format: CH moduleId nofDEs pos: x y z rot: thex, phix, they, phiy, thez, phiz DE deId envName copyNo pos: x y z rot: thex, phix, they, phiy, thez, phiz Example of station1 V2 data: CH 1 4 pos: rot: CH 2 4 pos: rot: DE 100 SQM1 1 pos: rot: DE 151 SQM1 2 pos: rot: DE 150 SQM1 3 pos: rot: DE 101 SQM1 4 pos: rot: DE 200 SQM2 1 pos: rot: DE 251 SQM2 2 pos: rot: DE 250 SQM2 3 pos: rot: DE 201 SQM2 4 pos: rot:

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 13 Geometry Segmentation Segmentation defines the detector layout, topology of pads, which is not present in the geometry definition In the current framework – User defined segmentations implement geometry functions (“get pad position”) in the global reference frame – Disconnected from geometry definition  In the new framework – User defined segmentations, derived from VDESegmentation base class, implement geometry functions in the local detection element frame – One general “global” segmentation per module, GeometrySegmentation, implement geometry functions in a global reference frame

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 14 Geometry Segmentation Implementation Bool_t AliMUONGeometrySegmentation::GetPadC( Int_t detElemId, Int_t ix, Int_t iy, Float_t& xg, Float_t& yg, Float_t& zg) { // Transform from pad to real coordinates if (!Notify(detElemId)) return false; if (!fCurrentSegmentation->HasPad(ix, iy)) return false; Float_t xl, yl, zl; fCurrentSegmentation->GetPadC(ix, iy, xl, yl, zl); fGeometryModule->Local2Global(detElemId, xl, yl, zl, xg, yg, zg); return true; }

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 15 Segmentation Classes

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 16 Use of Geometry Segmentation Geometry segmentation has different API from the old segmentation – Requires code transition from the old segmentation framework to the new one Detection element ID has to be consistently used together with the new geometry segmentation – Added to hit, digit,... class definitions

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 17 Present Status (1) Framework classes: In a separate library libMUONgeometry Independent from MUON code MUON specific classes that implement geometry are not included in this library Geometry: The whole MUON geometry (v1) is now defined via new framework – Still some problems to be solved Too many volumes going to ALIC from some builders (misuse of virtual envelopes) Overlaps for newly placed volumes

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 18 Present Status (2) Segmentation New segmentations per detection elements: Station12, Slat stations, Trigger stations All in CVS – AliMUONTest Testing new segmentation framework (in CVS) Instantiation of new geometry segmentations, printing pads positions, drawing pads AliMUONFactory, AliMUONChamber,... In transition to the new geometry and segmentation framework In development

ALICE Offline week, CERN 21 February 2005 I. Hrivnacova 19 Conclusions Concept of detection elements Consistent use of the same set of geometry transformations in both simulation and reconstruction Possibility to read transformations from a data file Concept of geometry modules – geometry builder classes per development teams Framework classes fully independent from MUON specific classes