The GAUSS Project

!!! THIS DOCUMENTATION REFERS TO THE Sim10 and older GAUSS SOFTWARE !!!

Be carefull as some information may be obsolete!

You can find more up-to-date information at

• the Simulation Project web site
• the new Gauss (based on Gaussino) software documentation web site
• the experiment-independent Gaussino software documentation web site
• the Gauss Gitlab repository for both Sim10 and Future
• the Gaussino GitLab repository

Gauss mimics what will happen in LHCb to allow understanding of its experimental conditions and its performance. It integrates two independent phases:

1. A Generator Phase consisting of the generation of the p-p collisions and the decay of the particles produced
2. A Simulation Phase consisting in the tracking of the particles in the detector and simulating the physics processes occuring in the experimental setup

Gauss is interfaced to various specialized packages available in the Physics community for the Generator phase (e.g. EvtGen for b-decays) and makes use of the Geant4 toolkit for the Simulation phase. For more specific information on each of the phases and the libraries used follow the links provided above.

Gauss is structured as a project containing an application package, also called Gauss, and a set of packages (component and linker both) specific to the physics simulation of the experiment and constituting the whole of the application. The application package provides the job options and main program for running the Gauss application. The default options are the configuration used in Production but for those specific to a given job (i.e. number of events, event type). Options for some different configuration of the application are provided. The configuration for different event types are provided in the DecFiles configuration package.

Coordinators and Contacts

The list of simulation core topics coordinators and the liasons for MC in the Physics working group and subdetectors can be found in this page

Meetings

A Simulation Applications meeting is held on Tuesdays at 16:30. to discuss progress, needs and proposed changes for Gauss and Boole.

Additional meetings for specific areas of development take place at regular intervals.

• Fast simulations
• Detector modeling and Geant4
• Future: Gaussino and Gauss'

This week meetings are listed here

Development and future releases

A list of work in progress or foreseen is available from the LHCb Simulation JIRA You can see the list of future versions of Gauss and other simulation software in the list of releases of the LHCb SImulation project on JIRA. .

The Gauss repository can be found on GitLab at https://gitlab.cern.ch/lhcb/Gauss. Refer to the Merge Requests for work in progress.

Reporting bugs

You can report bugs (Create an issue) or view bug histories (List issues with type 'Bug') via the LHCb simulation JIRA.

Productions

The production is currently in progress is called Sim09 and generates MC events for Run1, 2015 and 2016 data taking. Almost all events are being produced with conditions as similar as possible to these years. Some events are produced with conditions simular to special data taking as for the 1380 GeV beam energy.

Statistics on the resources used for MC production for each Physics and Physics Performance WG can be found at this link

Development productions are done for special investigations or to commission and validate new produciton simulation software. They are referred in the book-keeping as Dev. They should NOT be used for physics studies. The physics validated productions are in the folders correspoing to a given YEAR, e.g. 2012 or 2016.

The list of event types available for production and their documentation can be found in the DecFiles web pages.

The type of files that can be produced for simulated data can be found in this page

The production currently in progress for PHysics studies is Sim09c and a variation for the upgrade (Sim09c-UP02). For details refer to this page

Statistics for all data types are produced for the generator phase

• Sim09 statistic tables on generator efficiency

Documentation on the counters and on the script to produce the generator and simulation statistics:

• Instructions on the last tools and how to run them to produce the generator statistics
• Counters used to produce generator statistics

Reference documentation

Documentation for available releases can be found by following the links at the top of this page. The environment for working with a given version of Gauss should be set up with the SetupProject Gauss script.

Additional Documentation

• DecFiles reference documentation
• Type of files for MC Productions
• Controls for Gauss() configurable
• Available predefined simulation conditions in AppConfig
• Simulation twiki page
• Gauss F.A.Q.
• How to generate samples for first data
• Gauss Tutorials. If not already familiar with LHCb software you are recommended to first look at the LHCb basic tutorials
• Gauss User Guide (for version v18r3). Some things are obsolete, refer to job options in specific version when different
• Conventions to be adopted when writing LHCb code
• A mailing list lhcb-gauss@cern.ch is available

Project History

The history of dependencies and included packages can be viewed for any tagged version (including the ones that have been removed) from the GitLab web interface. Check for the versions with the relevant Gauss tags in GitLab For project dependencies see the GAUSS_vXrY/cmt/project.cmt or CMakeLists.txt files.