1. Marco Cattaneo, 20-May-19991 Event Reconstruction for LHCb  What is the scope of the project?  What are the goals (short+medium term)?  How do we organise ourselves?  How do we start?

2. Marco Cattaneo, 20-May-19992 Scope of reconstruction  Reconstruction is everything that takes raw data as input and produces new objects as output: High level triggers Calibration and alignment Creation of event tags (c.f. event classes at LEP) Full event reconstruction Creation of analysis objects etc.  At LHC we will use a database to store the data Implication is that reconstruction can be performed in several stages Full reconstruction may not be necessary for all events, or for all parts of an event

3. Marco Cattaneo, 20-May-19993 Some short term goals  Build a team of programmers Bring together physicists working on software Learn by doing design reviews, CRC workshops etc.  Define reconstruction strategies What can be done independently by subsystems What requires input from other subsystems (What are subsystems? - sub-detector, tracking, particle ID…) What should be sequence of actions What should be reconstruction output What initialisations are required and when  Identify and define external inputs Raw data event model Detector geometry, calibration, alignment

4. Marco Cattaneo, 20-May-19994 Some medium term goals  Build a reconstruction skeleton within Gaudi Implementing reconstruction phases -e.g.: common + specific (time dependent?) initialisation high level trigger reconstruction pass subsystem standalone reconstruction pass global reconstruction pass Placeholders for each subsystem  Make a reconstruction program “independent” of SICB Wrap existing SICB reconstruction code into algorithms Integrate new OO code  Agree (and begin to enforce) conventions Units, co-ordinate system Error reporting and handling, monitoring Coding rules, metrics, documentation, look and feel

5. Marco Cattaneo, 20-May-19995 Project organisation (1) short term  Team building Programming community is not large - do not isolate people not yet reconstruction vs. simulation vs. analysis never SICB vs. OO. Encourage same people to do both Regular meetings Start with a slot in the weekly Thursday computing meeting  Should be used by all who wish to present or review designs,requirements,code etc. Presentations and reviews of ongoing work also at physics meetings  Ensure that the physicist community is aware/involved in design choices  Project leader Collects requirements from subsystems Responsible for development of reconstruction strategies Interacts with GAUDI team Ensure specific needs of reconstruction are addressed by GAUDI Ensures milestones are set and adhered to

6. Marco Cattaneo, 20-May-19996 Project organisation (2) medium term  Identify a software contact in each subsystem Not necessarily a programmer BUT Has to be link person between project and subsystem: Discusses new software within subsystem community Collects requirements of subsystem Delivers requested information by agreed deadlines  e.g. what input does subsystem need from other subsystems?  e.g. how does subsystem plan to provide output needed by other subsystems?  e.g. verify that “wrapped” SICB algorithms work as expected  Incremental approach to medium term goals Attainable milestones every 2-3 months Dedicated meeting at each milestone: Review progress Agree next steps Attended by (at least) all contacts

7. Marco Cattaneo, 20-May-19997 How do we start?  Repeat this presentation at software week Including a name for the project  Take advantage of software week to Appoint a project leader Begin discussion of reconstruction strategies Begin collection of subsystem requirements Agree goals for end-November software week  Already some requests for design reviews We can schedule these from next week Should invite relevant experts at each review

8. Marco Cattaneo, 20-May-19998 A name?  For the architecture we have an architect  We now start a (re)construction project We need a civil engineerBRUNEL (B Reconstruction, UNderstanding Events in Lhcb)